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Virginia-Herndon-12851 Worldgate Drive Office Lease - WGP Associates LLC and SAVVIS Communications Corp.

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                                  OFFICE LEASE

                                     BETWEEN

                              WGP ASSOCIATES, LLC,
                      A VIRGINIA LIMITED LIABILITY COMPANY
                                  (AS LANDLORD)

                                       AND

            SAVVIS COMMUNICATIONS CORPORATION, A MISSOURI CORPORATION
                                   (AS TENANT)

Section                                                                     Page
1.   PRINCIPAL TERMS                                                          1
2.   GENERAL COVENANTS                                                        2
3.   TERM                                                                     3
4.   RENT                                                                     3
5.   COMPLETION OR REMODELING OF THE PREMISES                                 3
6.   OPERATING EXPENSES                                                       3
7.   SERVICES                                                                 3
8.   QUIET ENJOYMENT                                                          6
9.   DEPOSIT                                                                  6
10.  CHARACTER OF OCCUPANCY                                                   7
11.  MAINTENANCE, ALTERATIONS AND REENTRY BY LANDLORD8
12.  ALTERATIONS AND REPAIRS BY TENANT                                        9
13.  CONSTRUCTION LIENS                                                       9
14.  SUBLETTING AND ASSIGNMENT                                               10
15.  DAMAGE TO PROPERTY                                                      12
16.  INDEMNITY TO LANDLORD                                                   12
17.  SURRENDER AND NOTICE                                                    12
18.  INSURANCE, CASUALTY, AND RESTORATION OF PREMISES                        12
19.  CONDEMNATION                                                            13
20.  DEFAULT BY TENANT                                                       14
21.  DEFAULT BY LANDLORD                                                     16
22.  SUBORDINATION AND ATTORNMENT                                            17
23.  REMOVAL OF TENANT'S PROPERTY                                            18
24.  HOLDING OVER: TENANCY MONTH-TO-MONTH                                    18
25.  PAYMENTS AFTER TERMINATION                                              18
26.  STATEMENT OF PERFORMANCE                                                19
27.  MISCELLANEOUS                                                           19
28.  AUTHORITIES FOR ACTION AND NOTICE                                       21
29.  PARKING                                                                 21
30.  SUBSTITUTE PREMISES                                                     22
31.  BROKERAGE                                                               22
32.  COUNTERPARTS                                                            22
33.  ADDENDUM/EXHIBITS                                                       22


                                       1
<PAGE>




                                 LEASE AGREEMENT

THIS LEASE, dated as of January 24, 2000, is by and between WGP ASSOCIATES, LLC,
a Virginia limited  liability  company  ("Landlord")  and SAVVIS  COMMUNICATIONS
CORPORATION, a Missouri corporation ("Tenant").

                              W I T N E S S E T H :

     1. PRINCIPAL  TERMS.  Capitalized  terms,  first appearing in quotations in
this Section,  elsewhere in the Lease or any Exhibits,  are  definitions of such
terms as used in the  Lease and  Exhibits  and shall  have the  defined  meaning
whenever used.

        1.1     "BUILDING":                  Worldgate Plaza II, 12851 Worldgate
                                             Drive, Herndon, Virginia

        1.2     "PREMISES":                  approximately    80,582    rentable
                                             square  feet  located  on the  5th,
                                             6th,  7th,  and 8th  floors,  which
                                             comprise   the   entirety   of  the
                                             Building

        1.3     "INITIAL TERM":              10 years, 3 months
                                             "Commencement Date": March 1, 2000
                                             "Expiration Date": May 31, 2010



        1.4     "BASE RENT":                                    Annual Per Rentable
                                             Period              Square Foot Rate         Monthly
                                             ------             -------------------       -------
                                                                                 
                                             Months 1-12:               $25.85            $173,587.06 [See
                                                                                           Section 4]
                                             Months 13-24:              $26.68            $179,160.65
                                             Months 25-36:              $27.53            $184,868.54
                                             Months 37-48:              $28.41            $190,777.89
                                             Months 49-60:              $29.32            $196,821.54
                                             Months 61-72:              $31.24            $209,781.81
                                             Months 73-84:              $32.18            $216,094.06
                                             Months 85-96:              $33.15            $222,607.78
                                             Months 97-108:             $34.14            $229,255.79
                                             Months 109-120:            $35.16            $236,105.26
                                             Months 121-122:            $36.21            $243,156.19


          1.5     OPERATING EXPENSES:        Base Year: 2000
                                             Pro Rata Share: 100%

          1.6     DEPOSIT":                  $738,668.32   See Section 9

          1.7     "PERMITTED USE":           Primarily  as general  offices with
                                             ancillary  use for related  uses in
                                             accordance with Section 10

          1.8     "GUARANTOR":               Bridge Information Systems, Inc., a
                                             Missouri corporation

          1.9     PARKING:                   322 spaces in the Parking Garage or
                                             surface parking for the Building in
                                             accordance with Section 29

          1.10    LANDLORD'S NOTICE ADDRESS: WGP  ASSOCIATES,  LLC,  c/o  Miller
                                             Global  Properties,  LLC,  4643  S.
                                             Ulster Street,  Suite 1500, Denver,
                                             CO   80237,    Attn:    Donald   E.
                                             Spiegleman,  Esq. or Mr. Paul Hogan
                                             Facsimile:  303 694-0082 Telephone:
                                             303 773-0369


<PAGE>



                                                          
                       with a copy to Building Manager:      [name, address and phone numbers to be provided by Landlord]
                                                             Facsimile: _____________________
                                                             Telephone: ____________________


          1.11    RENT PAYMENT ADDRESS:      WGP  ASSOCIATES,  LLC,  c/o  Miller
                                             Global  Properties,  LLC,  4643  S.
                                             Ulster Street,  Suite 1500, Denver,
                                             CO 80237

          1.12    LANDLORD'S TAX I.D.:       84-1474051

          1.13    TENANT'S NOTICE ADDRESS:   Steven Gallant, Esq.
                                             Vice President and General Counsel
                                             Savvis Communications Corporation
                                             717 Office Parkway
                                             St. Louis, Mo. 63141
                                             Facsimile: 314 468-7550
                                             Telephone: 314 468 7517

                  with a copy to:            Richard A. Cohn
                                             Bryan Cave LLP
                                             700 Thirteenth Street, N.W.
                                             Washington, DC 20005-3960
                                             Facsimile: 202 508-6200
                                             Telephone: 202 508-6019

          1.14    TENANT'S TAX I.D.:         43-1727675

          1.15    LANDLORD'S BROKER:         Charles  E.   Smith   Real   Estate
                                             Services, L.P.

          1.16    COOPERATING BROKER:        Fred Ezra Company

          1.17    ATTACHMENTS:               [check if applicable]
                                             x       Addendum
                                             x       Work Letter
                                             x       Exhibit A - The Premises
                                             x       Exhibit A-1 - Building  and
                                                     Plaza I
                                             x       Exhibit B - Real Property
                                             x       Exhibit C - Operating
                                                     Expenses
                                                     Exhibit D - [Intentionally
                                                                  Deleted]
                                             x       Exhibit E - Rules and
                                                                 Regulations
                                             x       Exhibit F - Janitorial
                                                                 Specification
                                             x       Exhibit G - HVAC Rates
                                             x       Exhibit H - Parking
                                             x       Exhibit  I   -   Generator,
                                                     Generator Fuel Tank and UPS
                                                     Locations
                                             x       Exhibit J -  Subordination,
                                                     Non-Disturbance         and
                                                     Attornment Agreement

     2. GENERAL  COVENANTS.  Tenant covenants and agrees to pay Rent and perform
the  obligations  hereafter  set forth and in  consideration  therefor  Landlord
leases to Tenant the  Premises as  depicted  on the plat  attached as


                                       2
<PAGE>

EXHIBIT A,  together  with a  non-exclusive  right,  subject  to the  provisions
hereof,  to use  exterior  plazas,  common  areas,  or  other  areas on the real
property  legally  described  on  EXHIBIT  B and all other  common  areas of the
Building and the Building Complex (including, without limitation, parking areas,
sidewalks,  lobby and  corridors),  (the "Real  Property")  and such other areas
designated by Landlord for the exclusive or non-exclusive  use of the tenants of
the Building and Plaza I (as hereinafter defined),  including the Parking Garage
("Common Areas").  The "Building"  includes the building depicted and labeled as
Worldgate Plaza Tower II on the attached EXHIBIT A-1, inclusive of the 5th, 6th,
7th and 8th floors,  the  elevators  and stairs  serving  such  floors,  and the
elevator lobby on the first floor, exclusive of the parking garage portion lying
within the  footprint of the Building  depicted on EXHIBIT A-1. The Building and
the adjacent  building to be  constructed as depicted and labeled on EXHIBIT A-1
as  Worldgate  Plaza Tower I ("Plaza  I"),  Real  Property,  Common  Areas,  and
appurtenances  are  hereinafter  collectively  sometimes  called  the  "Building
Complex." The mechanical rooms  constituting  Common Areas on floors 5,6,7 and 8
of the Building shall be reserved to Landlord's use for Building  operations and
for Tenant's use, not the use of third  parties,  and use of the roof is subject
to the provisions of the Addendum.  The  mechanical  rooms  constituting  Common
Areas  elsewhere  in the  Building  shall be  reserved  for  Landlord's  use for
Building Complex operations  (including permitting the use by Tenant and tenants
of Plaza I, subject to Landlord's control of access and use).

     3. TERM.  The  Initial  Term of the Lease  commences  at 12:01 a.m.  on the
Commencement  Date and terminates at 12:00 midnight on the Expiration  Date (the
Initial Term together with any extensions  thereof is herein  referred to as the
"Term.").

     4. RENT.  Subject to the provisions  below,  commencing on the Commencement
Date and on the first day of each month  thereafter,  Tenant shall pay Base Rent
in the amount  stated in Section 1.4, in advance  without  notice (all  amounts,
including Base Rent, to be paid by Tenant  pursuant to this Lease as the context
requires are sometimes  referred to collectively  as "Rent(s)").  Rents shall be
paid  without set off,  abatement,  or  diminution,  at the address set forth in
Section  1.11  above,  or at such  other  place as  Landlord  from  time to time
designates  in writing.  Notwithstanding  anything to the  contrary set forth in
Section 1.4 above,  Tenant's  obligation to pay Base Rent for the Premises shall
be phased in on a floor by floor basis for the Premises in  accordance  with the
following:  Tenant's obligation to pay Base Rent for the 5th, 7th and 8th floors
(calculated  on the basis of $25.85  annually  per  rentable  square foot) shall
commence  on March 1,  2000;  Tenant's  obligation  to pay Base Rent for the 6th
floor  (calculated  on the basis of $25.85  annually per  rentable  square foot)
shall  commence  on June  1,  2000  and  thereafter  Tenant  shall  pay  Rent in
accordance with Section 1.4.

     5.  COMPLETION  OR  REMODELING  OF  THE  PREMISES.   Provisions   regarding
Landlord's  obligation  to complete the Building and the Premises and  regarding
the  completion  of tenant  finish work in the  Premises are set forth in a work
letter attached to this Lease (the "Work Letter"). "Initial Tenant Finish" means
the Premises in its as-is  condition as modified by all work, if any,  performed
by Landlord at its expense prior to the respective  Delivery Dates in accordance
with the Work  Letter.  Except as provided  in and  subject to the Work  Letter,
Landlord has no  obligation  for the  completion  or remodeling of the Premises.
Tenant will accept the Premises in its "as is" condition on the Delivery Date.

     6. OPERATING EXPENSES.  Tenant shall pay additional Rent in accordance with
EXHIBIT C attached hereto.

     7. SERVICES.

     7.1 Subject to the provisions  below,  Landlord agrees,  without charge, in
accordance  with standards  reasonably  determined by Landlord from time to time
for the Building  consistent  with the standards  observed by operators of first
class  office  buildings in the northern  Virginia  market:  (1) at all hours to
furnish  running  water at those  points of supply for general use of tenants of
the Building;  (2) during Ordinary Business Hours and such other times as may be
required by Tenant to furnish to interior  Common Areas heated or cooled air (as
applicable),   electrical  current,   janitorial   services,   and  maintenance;
(3) during  Ordinary  Business  Hours and such other times as may be required by
Tenant to  furnish  heated or cooled  air to the  Premises  consistent  with the
design  capacity of the Building  HVAC;  (4) to furnish,  subject to capacity of
building systems,  unfiltered treated chilled water for use in Tenant's packaged
HVAC systems


                                       3
<PAGE>

provided  that such  systems are  approved  by  Landlord,  including  strainers,
pumping systems and controls;  (5) to provide,  during Ordinary  Business Hours,
the general use of  passenger  elevators  for ingress and egress to and from the
Premises (at least one such  elevator  shall be available at all times except in
the case of emergencies or repair);  (6) to provide janitorial  services for the
Premises in accordance with the attached EXHIBIT F (including  window washing of
the outside of exterior  windows and  relamping and  replacement  of ballasts in
flourescent  ceiling light fixtures in the Premises);  and (7) to cause electric
current to be supplied to the Premises for Tenant's  Standard  Electrical  Usage
(items (1) through (7) are collectively called  "Services").  "Tenant's Standard
Electrical  Usage"  means  electricity  for  normal  office  purposes  including
fluorescent and incandescent  lighting (including task and task ambient lighting
systems) and for normal office equipment,  including duplicating  (reproduction)
machines and personal  computers  (provided  they do not require any  additional
voltage,  special electrical or HVAC requirements beyond the systems existing in
the Premises),  and internal communications  systems.  "Ordinary Business Hours"
means 8:00 a.m. to 6:00 p.m. Monday through Friday and 8:00 a.m. to 1:00 p.m. on
Saturdays, Legal Holidays excepted. "Legal Holidays" mean New Year's Day, Martin
Luther King Day,  Inauguration Day, Presidents' Day, Memorial Day,  Independence
Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving Day, Christmas Day, and
such  other  national  holidays  hereafter  established  by  the  United  States
Government.  The  security  system  shall be  operative  at all times  except as
required for repair or maintenance and shall restrict access (in accordance with
the security  system  specifications)  to the main Building  lobby and access to
individual floors from the elevator on such days and at such hours as Tenant may
request by notice to Landlord; Tenant shall have access to the Building 24 hours
a day, 7 days a week  (subject to the  provisions  of this Lease).  Any security
system or other security  measures  (collectively  "security") that Landlord may
undertake are for  protection of the physical  structures  only and shall not be
relied upon by Tenant,  its  agents,  employees  or  invitees  to protect  their
person, or property,  including Tenant's Property.  Tenant shall not do anything
to circumvent or allow others to circumvent security.  Tenant shall have a right
to install its own security system in the Building  provided that such system is
installed in such a manner as to permit the  continued  operation of  Landlord's
security  and life safety  systems or is a substitute  security  system (for the
Building and Premises and Tenant's  allocated  portion of parking  level four of
the parking  garage,  as referred to in Section 29, but  excluding  the security
system for the main access controls for the parking garage), reasonably approved
by Landlord, that interfaces with Landlord's life safety systems to permit their
continued  operation.  Tenant shall provide Landlord with keys,  access cards or
access numbers for any security system installed by Tenant to permit Landlord to
have access to the Building and  Premises.  If a substitute  security  system is
used, Tenant shall deliver to Landlord, at the expiration or earlier termination
of the Lease,  all manuals and other  equipment  required  for  operation of the
system and leave in place all  cabling and related  equipment  installed  in the
Building.  Landlord  shall not be liable  for any  failure  of any  security  to
operate or for any  breach or  circumvention  of the  security  by  others,  and
Landlord makes no  representations  or warranties  concerning the  installation,
performance  and  monitoring  of the  security  or that it will  detect or avert
occurrences  which any such security is intended or expected to detect or avert.
Landlord shall maintain the security which it elects to install in good repair.

     7.2  Electricity  for the Building,  including the entirety of the Premises
shall be separately  metered and paid by Tenant upon billing by service provider
of Landlord (based on the actual costs incurred to the provider,  without markup
or profit to Landlord) and electricity shall not be included in amounts required
to be paid by Tenant as Operating Expenses under EXHIBIT C. In addition,  Tenant
shall be  responsible  for and shall pay promptly,  directly to the  appropriate
supplier, all charges for telephone,  interior landscape maintenance,  and other
materials and services furnished directly to Tenant or the Premises,  or used by
Tenant  in or about  the  Premises  during  the  Term,  together  with any taxes
thereon.  Tenant  shall have the right to  contract  for fiber optic cable to be
installed,  at Tenant's  expense,  from the street  right-of-way to the Premises
using  existing  conduits  installed by Landlord for use of this  Building or by
installation of additional conduits,  subject to Landlord's  reasonable approval
based on the  capacity,  design and location of such  conduits.  "Excess  Usage"
means any usage of electricity  (1) during other than Ordinary  Business  Hours;
(2) in an amount in excess of Tenant's  Standard  Electrical  Usage;  or (3) for
Special  Equipment  or for standard  HVAC  services  during other than  Ordinary
Business Hours.  "Special Equipment" means (a) any equipment consuming more than
0.5 kilowatts at rated  capacity,  (b) any  equipment  requiring a voltage other
than  120  volts,  single  phase,  or (c)  equipment  that  requires  the use of
self-contained  HVAC units.  If Tenant desires  Excess Usage,  Landlord will use
reasonable  efforts to supply the same. Tenant shall reimburse  Landlord for all
Landlord's  costs of providing  services for Excess Usage,  including  costs for
materials,   additional  wear  and  tear  on  equipment,  utilities,  and  labor
(including fringe and overhead costs). Computation of such costs will be made by
Landlord's  engineer,  based on his engineering survey of Tenant's Excess Usage.


                                       4
<PAGE>

Tenant shall reimburse  Landlord for all additional  costs, if any,  incurred by
Landlord as a result of Tenant's installation or use of Special Equipment, other
than electrical costs (which shall be included in the metered  electricity),  as
reasonably   determined   by  Landlord's   engineer,   including  all  costs  of
supplementing  the Building HVAC Systems and/or extending or  supplementing  any
electrical  service,  as Landlord  determines is necessary,  as a result of such
Special  Equipment.  "Special  Equipment"  means  (a)  any  equipment  requiring
modification or supplementation of the Building HVAC or electrical systems,  (b)
any  equipment  requiring a voltage other than 120 volts,  single phase,  or (c)
equipment that requires the use of self-contained  HVAC units. If Tenant desires
use of Building  services  after  Ordinary  Business  Hours,  Tenant  shall give
Landlord  such  prior  notice as is  reasonably  required  to  arrange  for such
after-hours services; provided, however, that only 2 hours prior notice shall be
required if such notice is given during  Ordinary  Business  Hours during Monday
through Friday (or such lesser notice as is required so long as after hours HVAC
is under the  control  of the  Charles E. Smith  Environmental  Control  Center,
pursuant to the applicable Building engineering services agreement). Charges for
Building HVAC use after Ordinary  Business  Hours, to be used in determining the
charges referred to above, are set forth on the attached EXHIBIT G. Tenant shall
also reimburse  Landlord for all costs of supplementing the Building HVAC System
and/or extending or supplementing any electrical service, as Landlord determines
is necessary, as a result of Tenant's Excess Usage. Prior to installation or use
of Special  Equipment or  operation  of the  Premises  for extended  hours on an
ongoing basis, Tenant shall notify Landlord of such intended installation or use
and obtain  Landlord's  consent.  Tenant may request  that  Landlord  install at
Tenant's  cost a check meter and/or flow meter to determine the cost of Tenant's
Excess  Usage.  Tenant shall also pay the cost of  replacing  light bulbs and/or
tubes and ballast used in all lighting in the Premises  other than that provided
by Landlord to all tenants of the Building.

     7.3 If Tenant  requires  janitorial  services  other than those included as
standard  Services,  Tenant shall  separately pay for such services monthly upon
billings by Landlord, or Tenant shall, at Landlord's option, separately contract
for such services  with the same company used by Landlord to furnish  janitorial
services to the Building.

     7.4  Landlord  may  discontinue,   reduce,   or  curtail  Services  (either
temporarily or permanently) when necessary due to accident beyond the reasonable
control of Landlord,  repairs, strikes, lockouts,  Applicable Laws, or any other
happening  beyond  Landlord's  reasonable  control.  Landlord  is not liable for
damages to Tenant or any other party as a result of any interruption, reduction,
or  discontinuance  of Services  (either  temporary or permanent)  nor shall the
occurrence  of any such event be  construed  as an eviction of Tenant,  cause or
permit an abatement,  reduction or setoff of Rent, or operate to release  Tenant
from  Tenant's   obligations;   provided,   however,  that  notwithstanding  the
foregoing,  if the  Premises  should  become  unsuitable  for  Tenant's use as a
consequence  of a cessation of Services  (other than an  interruption  resulting
from a fire or other  casualty,  which shall be governed  by the  provisions  of
Section 18) (excluding, however, acts or omissions of Tenant or Tenant's Agents,
as defined below) and persists for more than three (3) consecutive business days
(an  "Interfering  Event"),  then  Tenant  shall  be  entitled  to an  equitable
abatement  of Rent to the extent of the  interference  with  Tenant's use of the
Premises  occasioned  thereby from the date of the  Interfering  Event until the
date the Services are restored to the Premises.  If Tenant  continues to use any
part of the Premises to conduct its  business,  the Rent will only abate for the
untenantable part not used. Should any


                                       5
<PAGE>

malfunction of the Building improvements or facilities required to be maintained
by  Landlord  occur that  affect  such  Services,  Landlord  shall  repair  such
malfunction as soon as reasonably  practicable with reasonable  diligence and in
the event of the  discontinuance,  reduction or  curtailment of Services for any
reason, Landlord shall use commercially reasonable efforts to have such services
restored as soon as reasonably practicable.

     7.5 Tenant shall  promptly  notify  Landlord of any accidents or defects in
the Building of which Tenant has actual  knowledge,  including defects in pipes,
electric  wiring,  and HVAC  equipment,  and of any condition which is likely to
cause injury or damage to the Building or any person or property therein.

     8. QUIET  ENJOYMENT.  So long as an Event of Default has not  occurred  and
which is  continuing,  Tenant is entitled to the quiet  enjoyment  and  peaceful
possession of the Premises  subject to the  provisions  of this Lease.  Landlord
shall under no  circumstances  be held responsible for restriction or disruption
of access to the Building from public  streets  caused by  construction  work or
other actions taken by or on behalf of governmental authorities,  or for actions
taken by other  tenants  (their  employees,  agents,  visitors,  contractors  or
invitees), or any other cause not entirely within Landlord's direct control, and
same shall not constitute a constructive eviction of Tenant nor give rise to any
right or remedy of Tenant against  Landlord of any nature or kind. This covenant
of quiet  enjoyment  is in lieu of any covenant of quite  enjoyment  provided or
implied by law,  and Tenant  expressly  waives any such other  covenant of quiet
enjoyment to the extent broader than the covenant contained in this Section.

     9. DEPOSIT.

     9.1 By not later than 10 days  following  the  delivery  by Landlord of the
fully executed Lease to Tenant,  Tenant shall deposit,  and will keep on deposit
at all times during the Initial Term,  with Landlord the Deposit as security for
the payment and performance of Tenant's obligations under this Lease. If, at any
time,  after an Event of Default by  Tenant,  Landlord  has the right to use the
Deposit,  or so much thereof as necessary,  in payment of Rent, in reimbursement
of any expense  incurred by Landlord,  and in payment of any damages incurred by
Landlord by reason of such Event of  Default.  In such  event,  Tenant  shall on
demand of Landlord  forthwith  remit to Landlord a sufficient  amount in cash to
restore the Deposit to the original  amount.  If the entire Deposit has not been
utilized,  the remaining amount will be refunded to Tenant or to whoever is then
the holder of Tenant's interest in this Lease, without interest,  within 60 days
after  expiration  of the  Initial  Term.  Landlord  may deliver the Deposit (or
rights to the  Deposit  account,  as  referred  to above)  to any  purchaser  of
Landlord's  interest in the  Premises  and  Landlord  shall be  discharged  from
further  liability  therefor  following  actual  delivery  of such  Deposit  and
assumption by the  transferee of Landlord's  obligations  with respect  thereto.
Tenant  agrees  that if a  Mortgagee  succeeds  to  Landlord's  interest  in the
Premises by reason of foreclosure or deed in lieu of foreclosure,  Tenant has no
claim against the Mortgagee for the Deposit or any portion  thereof  unless such
Mortgagee has actually  received the same from  Landlord.  If claims of Landlord
exceed the Deposit, Tenant shall remain liable for the balance.

     9.2  Subject  to the  provisions  of Section  9.4,  if there is no Event of
Default  by  Tenant  as of the end of the end of the 36th  month  following  the
Commencement Date or circumstances which with the mere passage of time or giving
of notice would constitute an Event of Default  following such date, the Deposit
shall be  reduced by  $184,667.08;  if there is Event of Default by Tenant as of
the  end of the  end of the  36th  month  following  the  Commencement  Date  or
circumstances  which  with the mere  passage  of time or giving of notice  would
constitute an Event of Default,  such reduction shall occur thereafter only upon
the  curing of such  Event of  Default  or  circumstances,  as  applicable.  The
remaining  Deposit  shall then be held for the balance of the Initial Term until
the  Expiration  Date (as provided in Section 1.3),  subject to  application  in
accordance with this Section.

     9.3 The  Deposit  shall  be in the  form  of  immediately  available  funds
deposited  in a separate  interest-bearing  account in  Landlord's  name,  which
interest shall be considered  additional Deposit or,  alternatively Tenant shall
have  the  right  to  request  Landlord's  consent  to  the  substitution  of an
irrevocable transferable letter of credit for the Deposit and Landlord shall not
withhold  consent to such  substitution  subject to such letter of credit  being
issued by a lending  institution  approved by Landlord  and the letter of credit
being in a form approved by Landlord ("Letter of


                                       6
<PAGE>

Credit"), such approval not to be unreasonably withheld, conditioned or delayed,
in the amount of the Deposit,  subject to reduction  as provided  above.  If the
Letter of Credit would  otherwise  expire prior to the Expiration  Date,  Tenant
shall  present  Landlord  with an extension or renewal of the initial  Letter of
Credit,  or a  substitute  Letter of Credit in the same form,  not later than 60
days prior to the  expiration  date of such  initial  Letter of  Credit,  from a
lending institution subject to Landlord's  reasonable approval;  such extension,
renewal or substitute  Letter of Credit shall be effective no later than the day
prior to the  expiration of the initial  Letter of Credit and shall  continue in
effect for not less than the period ending with the Expiration Date and shall be
in the  amount  provided  above.  Tenant  agrees  that in an Event of Default by
Tenant (as defined in Section  20),  Landlord  shall have a right to present the
Letter of Credit (or the renewal,  extension or  substitute)  for payment,  with
amounts  received to be held and applied in accordance  with this  Section.  Any
failure of Tenant to provide  Landlord with an extension,  renewal or substitute
Letter of Credit,  as  required  hereunder,  shall be deemed an Event of Default
under the Lease and Landlord  shall have a right to present the Letter of Credit
in accordance with the foregoing provision. If the Letter of Credit has not been
presented  for  payment  in  accordance  with  this  Section  on or  before  the
Expiration  Date,  Landlord  shall return the Letter of Credit to Tenant  within
thirty (30) days after the Expiration  Date.  Tenant agrees that in the event of
any  assignment  or this  Lease or  mortgage,  Landlord  shall have the right to
transfer the Letter of Credit or  substitute  to the assignee or mortgagee  (and
Tenant  shall  pay any  costs or fees  charged  by the  issuer  to  permit  such
transfer),  and if the Letter of Credit has been  transferred as provided above,
Tenant  shall  look  solely to such  transferee  for the return of the Letter of
Credit (or  substitute),  provided  that Landlord  shall give written  notice to
Tenant of transfer of Landlord's interest resulting in transfer of the Letter of
Credit and the  transferee  shall  assume the  obligation  to return the same to
Tenant in accordance  with this Lease.  Landlord shall deliver the  then-current
effective  Letter of Credit to Tenant upon receipt of any conforming  renewal or
substitute  Letter of Credit  provided in  accordance  with this  Paragraph  and
cooperate  with the  issuing  bank to effect the  release  of such  then-current
effective Letter of Credit.

     9.4 In accordance  with  Paragraph 6 of the Addendum,  the  obligations  of
Tenant are  guaranteed by the Guarantor,  Bridge  Information  Systems,  Inc., a
Missouri  corporation,  pursuant  to the  terms of the  Guaranty.  The  Guaranty
provides  for the ability to  substitute  Tenant's  parent  corporation,  Savvis
Communications  Corporation,  a Delaware corporation,  as Guarantor,  subject to
increasing the amount of the Deposit to a total of  $3,196,419.30 in the form of
the Letter of Credit referred to above; the effective date of such  substitution
is referred to as the Substitution Date. In such event, the following  provision
shall be applicable,  in  substitution  for the provisions of Section 9.2 above:
(i) if there  is no  Event of  Default  (or  circumstances  which  with the mere
passage of time or giving of notice  would  constitute  an Event of  Default) by
Tenant  as of the end of the  12th  month  following  the  Substitution  Date or
circumstances  which  with the mere  passage  of time or giving of notice  would
constitute an Event of Default following such date, the Deposit shall be reduced
by  $351,107.29;   (ii)  likewise,   on  each  anniversary   thereafter  of  the
Substitution  Date through and  including  the 7th  anniversary,  if there is no
Event of Default (or circumstances which with the mere passage of time or giving
of notice  would  constitute  an Event of Default) as of such date,  the Deposit
shall be additionally  reduced by $351,107.29  (however,  in no event shall such
reductions  result  in  reduction  below   $738,668.32);   (iii)  if  there  are
circumstances  which  with the mere  passage  of time or giving of notice  would
constitute  an  Event  of  Default  as of  the  respective  anniversary  of  the
Substitution Date, the respective reduction shall occur thereafter only upon the
curing of such  Event of  Default  or  circumstances,  as  applicable;  (iv) the
remaining  Deposit as of the 7th  anniversary of $738,668.32  shall then be held
until the  Expiration  Date of the  Initial  Term,  subject  to  application  in
accordance  with this Section.  The reduction of the amount of the Deposit shall
be effected by amendment of the  then-effective  Letter of Credit (by  amendment
executed by the issuer and Landlord) or by Tenant's substitution of a substitute
Letter of Credit in the respective reduced amount (in which event Landlord shall
surrender the Letter of Credit being held as of the substitution upon receipt of
the substitute).

     10.  CHARACTER  OF  OCCUPANCY.  Tenant  shall  occupy the  Premises for the
Permitted  Use and for no other  purpose,  and use it in a  careful,  safe,  and
proper manner and pay on demand for any damage to the Premises  caused by misuse
or abuse by Tenant,  Tenant's agents or employees,  or any other person entering
upon the Premises under express or implied  invitation of Tenant  (collectively,
"Tenant's Agents").  The term "Permitted Use" shall mean: general office use for
administrative,  clerical, and professional office purposes and the operation of
internet and telecommunications services and Collocation Services (as defined in
Section 14.7)  (collectively,  the "Primary Use") and for  activities  ancillary
thereto (the  "Ancillary  Uses")  provided that  Ancillary Uses shall not be the
primary use of


                                       7
<PAGE>

the Premises, are permitted by Applicable Laws (as hereinafter defined), and are
expressly  approved  by  Landlord,  which  approval  shall  not be  unreasonably
withheld if such uses are consistent  with first class  suburban  general office
building uses and so long as in keeping with Building's  first-class quality and
allowed under PDC zoning applicable to the Building. Tenant shall be responsible
for  obtaining any  approvals or permits  required for the Ancillary  Uses under
Applicable Laws and the Declaration.  Tenant, at Tenant's expense,  shall comply
with  all  applicable  federal,  state,  city,  quasi-governmental  and  utility
provider  laws,  codes,  rules,  and  regulations  now or  hereafter  in  effect
("Applicable  Laws") which impose any duty upon  Landlord or Tenant with respect
to the  occupation or  alteration  of the  Premises.  Tenant shall not commit or
permit waste or any nuisance on or in the Premises.  Tenant agrees not to store,
keep, use, sell,  dispose of or offer for sale in, upon or from the Premises any
article or substance  prohibited by any insurance  policy  covering the Building
Complex nor shall Tenant keep,  store,  produce or dispose of on, in or from the
Premises or the Building Complex any substance which may be deemed an infectious
waste or hazardous  substance under any Applicable Laws, except customary office
and cleaning supplies or supplies customarily associated with the Primary Use of
the  Premises  that  are  disclosed  to  Landlord  and are  stored  and  used in
accordance with Applicable Laws and applicable industry  standards.  Landlord is
responsible  for  complying  with  Applicable  Laws  relating  to  the  Building
(excluding  the  Premises)  and its  Common  Areas,  including  Title III of the
Americans  with  Disabilities  Act of 1990  (the  "ADA")  and the  costs of such
compliance  with existing  Applicable Laws as of the date hereof will be paid by
Landlord  and will not be  charged  back to  Tenant.  The  method  and timing of
compliance  will be within  Landlord's  discretion.  Tenant is  responsible  for
compliance with all existing and any new Applicable Laws,  including ADA, within
the Premises.  Landlord will include  Landlord's  future compliance costs due to
changes in or new  Applicable  Laws as an Operating  Expense in accordance  with
Exhibit  C. To the  extent  that  Tenant  is  responsible  for  compliance  with
Applicable  Laws,  Tenant  shall  have  the  right  to  contest  by  appropriate
proceedings  diligently  conducted in good faith, in the name of Tenant or, with
the prior written  consent of Landlord,  in the name of Landlord,  or both,  the
validity or application of any Applicable Laws of any nature affecting Tenant or
its use of the Premises.  If compliance with any of such Applicable Laws legally
may be delayed pending the prosecution of any proceeding,  without incurring any
lien,  charge or liability of any kind against the Building and/or the Premises,
or against  Landlord's  interest in the Building  and/or the Premises or sale of
the Building and/or the Premises,  and without  subjecting Tenant or Landlord to
any  liability,  civil or  criminal,  interest or penalty for failure to comply,
Tenant may delay compliance until the final determination of the proceeding.

     11. MAINTENANCE, ALTERATIONS AND REENTRY BY LANDLORD.

     11.1 Landlord will (i) make repairs and  replacements to HVAC,  mechanical,
life safety and  electrical  systems in the Premises (to the extent such systems
are Building standard) deemed necessary by Landlord for normal operations of the
Building  Complex;  and (ii)  provide  upkeep,  maintenance,  and repairs to all
Common Areas of the Building Complex,  including without  limitation the Parking
Facilities,  and all  structural  elements of the  Building,  including  without
limitation the roof,  exterior  walls  (including  windows and glass),  interior
bearing walls, foundations, footings, and all exterior surfaces of the Building.
Landlord  shall  perform its  obligations  under this  Section  11.1 in a manner
consistent with other first class office buildings in the northern Virginia area
and in accordance  with Applicable  Laws.  Except as provided in this Section or
otherwise  expressly  required in this Lease,  Landlord is not  required to make
improvements or repairs to the Premises during the Term.

     11.2  Landlord  or  Landlord's  agents may at any time  enter the  Premises
without notice in case of emergency and for  performance of janitorial  services
and in all other  instances  after  reasonable  prior oral or written  notice to
Tenant and subject to compliance  with  Tenant's  reasonable  security  measures
(which may include an escort) for examination and inspection,  or to perform, if
Landlord elects, any obligations of Tenant which Tenant fails to perform or such
cleaning, maintenance, janitorial services, repairs, replacements, additions, or
alterations  as  Landlord  deems  necessary  for  the  safety,  improvement,  or
preservation  of the Premises or other  portions of the  Building  Complex or as
required by Applicable  Laws.  Landlord or  Landlord's  agents may also show the
Premises to prospective purchasers,  Mortgagees and during the last 12 months of
the Term, to prospective tenants,  upon not less than 48 hours prior notice. Any
such reentry does not  constitute an eviction or entitle  Tenant to abatement of
Rent.  Landlord may make such  alterations  or changes in other  portions of the
Building Complex as Landlord desires so long as such alterations and


                                       8
<PAGE>

changes do not unreasonably interfere with Tenant's occupancy of the Premises or
use of the Common  Areas or conflict  with the other  provisions  of this Lease.
Landlord  may use the  Common  Areas  and one or more  street  entrances  to the
Building  Complex as may be necessary in  Landlord's  judgment to complete  such
work.

     12. ALTERATIONS AND REPAIRS BY TENANT.

     12.1 Tenant shall not make any alterations to the Premises during the Term,
including installation of equipment or machinery which requires modifications to
existing  electrical  outlets or increases  Tenant's usage of electricity beyond
Tenant's Standard Electrical Usage (collectively  "Alterations") without in each
instance first  obtaining the written  consent of Landlord,  which consent shall
not be  unreasonable  withheld,  conditioned or delayed.  Landlord's  consent or
approval of the plans,  specifications  and working drawings for any Alterations
shall not constitute any warranty or  representation  by Landlord (and shall not
impose any liability on Landlord) as to their completeness,  design sufficiency,
or compliance with  Applicable  Laws;  provided,  however,  Tenant may,  without
Landlord's consent,  perform interior  non-structural  Alterations not involving
modifications  to the Base  Building  plumbing,  electrical,  mechanical or life
safety  systems (as  distinguished  from the  portions of such  systems  located
within the  Premises  that are  installed  by Tenant as Initial  Tenant  Finish)
provided the cost of any particular  Alterations  (taking into account  together
all  Alterations  being made as part of a common or phased plan) does not exceed
Seventy Five Thousand Dollars  ($75,000)(such  cost limit shall not, however, be
applicable to Alterations  on the 6th floor).  Tenant shall at its cost: pay all
engineering and design costs incurred by Landlord as to all Alterations,  obtain
all governmental permits and approvals required, and cause all Alterations to be
completed in compliance  with  Applicable  Laws and  requirements  of Landlord's
insurance.  All such work relating to  Alterations  shall be performed in a good
and  workmanlike  manner,  using new  materials  and equipment at least equal in
quality to the Initial Tenant Finish.  All  Alterations,  repair and maintenance
work  performed  by  Tenant  shall be done at  Tenant's  expense  by  Landlord's
employees or, with  Landlord's  prior consent,  which shall not be  unreasonably
withheld, conditioned or delayed, by other persons requested by Tenant; however,
if such work is not performed by Landlord's employees, Tenant shall pay Landlord
a  supervisory  fee upon  receipt of an  invoice.  If Landlord  authorizes  such
persons to perform work,  Tenant shall deliver to Landlord prior to commencement
certificates issued by insurance companies qualified to do business in the state
in which the Premises are located, evidencing that worker's compensation, public
liability insurance,  and property damage insurance (in amounts,  with companies
and on forms  satisfactory  to  Landlord)  are in force  and  maintained  by all
contractors  and  subcontractors  engaged to perform  such work.  All  liability
policies  shall name  Landlord,  Building  Manager,  and Mortgagee as additional
insureds.  Each certificate shall provide that the insurance may not be canceled
or modified  without 10 days' prior  written  notice to Landlord and  Mortgagee.
Landlord  also has the  right  to post  notices  in the  Premises  in  locations
designated by Landlord  stating that Landlord is not responsible for payment for
such work and containing such other information as Landlord deems necessary. All
such work shall be performed in a manner which does not  unreasonably  interfere
with the performance of Landlord's  rights and obligations  under this Lease, or
impose  additional  expense  upon  Landlord  in the  operation  of the  Building
Complex.

     12.2 Tenant shall keep the Premises in as good order, condition, and repair
and in an orderly  state,  as on the  Commencement  Date,  loss by fire or other
casualty or ordinary wear excepted.

     12.3 All Alterations,  including partitions, paneling, carpeting, drapes or
other window  coverings,  and light  fixtures (but not including  movable office
furniture,  equipment  and  other  property  not  permanently  attached  to  the
Building), are deemed a part of the real estate and the property of Landlord and
remain upon and be surrendered with the Premises at the end of the Term, whether
by lapse of time or otherwise,  unless Landlord notifies Tenant no later than 15
days  prior to the end of the Term that it elects to have  Tenant  remove all or
part of such  Alterations,  and in such event,  Tenant shall at Tenant's expense
promptly remove the Alterations  specified and restore the Premises to its prior
condition, reasonable wear and tear excepted.

         13.  CONSTRUCTION  LIENS.  Tenant  shall  pay for all work  done on the
Premises by Tenant or at its request (other than the Initial Tenant Finish) of a
character  which may result in liens on  Landlord's  or  Tenant's  interest  and


                                       9
<PAGE>

Tenant will keep the Premises free of all construction liens, and other liens on
account of such work. Tenant  indemnifies,  defends,  and saves Landlord and all
Mortgagees  harmless from all liability,  loss,  damage, or expenses,  including
attorneys' fees, on account of any claims of laborers, materialmen or others for
work  performed  or for  materials  or supplies  furnished  to Tenant or persons
claiming under Tenant.  If any lien is recorded against the Premises or Building
or any suit  affecting  title  thereto is commenced as a result of such work, or
supplying  of  materials,  Tenant  shall cause such lien to be removed of record
within 10 days after  notice  from  Landlord.  If Tenant  desires to contest any
claim, Tenant must either arrange for release of such lien and substitution of a
bond or other  collateral  (in  accordance  with  Applicable  Laws)  or  furnish
Landlord  adequate  security  of at least 150% of the amount of the claim,  plus
estimated costs and interest and, if a final judgment  establishing the validity
of any lien is entered,  Tenant shall  immediately  pay and satisfy the same. If
Tenant  fails to  proceed as  aforesaid,  Landlord  may pay such  amount and any
costs, and the amount paid,  together with reasonable  attorneys' fees incurred,
shall be immediately due Landlord upon notice.

     14. SUBLETTING AND ASSIGNMENT.

     14.1 Except as provided in Section  14.7,  Tenant shall not sublet any part
of the  Premises  nor assign or  otherwise  transfer  this Lease or any interest
herein  (sometimes  referred to as "Transfer," and the subtenant or assignee may
be referred  to as  "Transferee")  without  the consent of Landlord  first being
obtained,  which  consent  will not be  unreasonably  withheld,  conditioned  or
delayed  provided that: (1) Tenant complies with the provisions of Section 14.4;
(2)  Landlord  declines to  exercise  its rights  under  Section  14.3;  (3) the
Transferee is engaged in a business and the portion of the Premises will be used
for the Permitted Use in a manner which is in keeping with the then standards of
the Building and does not conflict with any exclusive use rights  granted to any
other  tenant  of the  Building  Complex;  (4)  the  Transferee  has  reasonable
financial worth in light of the responsibilities  involved; (5) Tenant is not in
default  at  the  time  it  makes  its  request;  (6)  the  Transferee  is not a
governmental  or  quasi-governmental  agency;  and (7) the  Transferee  is not a
tenant or currently  negotiating a lease with Landlord in any building  owned by
Landlord  in the  metropolitan  area  of the  Building  Complex  (including  the
Building  Complex).  Transfer  includes a sale by Tenant of substantially all of
its  assets or stock if Tenant is a  publicly  traded  corporation,  a merger of
Tenant with another  corporation,  the transfer of 49% or more of the stock in a
corporate tenant whose stock is not publicly traded,  or transfer of 49% or more
of the  beneficial  ownership  interests in a partnership  or limited  liability
company  tenant.  If any  Alterations  to the  Premises or the Common  Areas are
required by Applicable  Laws in connection  with such Transfer or the particular
business  of such  Transferee,  such  Alterations  shall be subject to the prior
approval of Landlord  (which  approval shall not be  unreasonably  withheld) and
Tenant shall bear the cost of such Alterations.

     14.2  Following any Transfer in accordance  with this Section 14,  Landlord
may, during the continuance of an Event of Default by Tenant,  collect rent from
the  Transferee or occupant and apply the net amount  collected to the Rent, but
no Transfer or  collection  will be deemed an  acceptance  of the  Transferee or
occupant as Tenant or release Tenant from its obligations. Consent to a Transfer
shall  not  relieve  Tenant  from  obtaining  Landlord's  consent  to any  other
Transfer.  Notwithstanding  Landlord's  consent  to  a  Transfer,  Tenant  shall
continue to be primarily liable for its obligations. If Tenant collects any rent
or other amounts from a Transferee in excess of the Rent (after deduction of the
reasonable  costs of such  Transfer)  for any monthly  period,  Tenant shall pay
Landlord fifty percent (50%) of the excess monthly, as and when received.

     14.3  Notwithstanding  the above (and except for a Transfer permitted under
Section 14.7),  if Tenant requests  Landlord's  consent to sublet 49% or more of
the Premises for all or  substantially  all of the remainder of the then-current
Term of the Lease or assign Tenant's interest in the Lease,  Landlord may refuse
to grant such consent in its sole  discretion and terminate this Lease as to the
portion  of the  Premises  with  respect to which such  consent  was  requested;
provided,  however,  if Landlord  does not consent and elects to  terminate  the
Lease as to such  portion,  Tenant may within 15 days after notice from Landlord
to this effect  withdraw  Tenant's  request  for  consent.  If such  termination
occurs,  it shall be effective on the date  designated in a notice from Landlord
and shall not be more than 30 days following such notice.


                                       10
<PAGE>

     14.4 Tenant must notify Landlord at least 30 days prior to the desired date
of the  Transfer  ("Tenant's  Notice"),  excluding  a Transfer  permitted  under
Section 14.7.  Tenant's  Notice shall describe the portion of the Premises to be
transferred and the terms and conditions.  Landlord has, without obligation,  15
days  following  receipt of Tenant's  Notice to (i) propose a subtenant for such
space (which  subtenant  shall be subject to  reasonable  approval of Tenant) or
(ii) exercise its rights pursuant to Section 14.3 if Tenant's  Notice  discloses
that 49% or more of the Premises is involved; provided, however, that Landlord's
option in  clause  (i) shall not be  applicable  until 24 months  following  the
Commencement  Date so long as the  Transfers  are  subleases for a period not to
exceed 36 months which which do not involve more than 33% of the Premises in the
aggregate.  If the space covered by Tenant's  Notice is subleased to a sublessee
proposed by Landlord, rent and other sums due from the subtenant will be paid to
Tenant directly and Landlord has no  responsibility  for the performance by such
subtenant of its  obligations  under its sublease with Tenant.  If Landlord does
not  exercise  its rights  under  clause (i) or clause (ii) within 15 days after
receipt of Tenant's  Notice,  Landlord shall be deemed to have waived its rights
under those clauses with respect to the proposed transaction and Tenant shall be
free to sublet the specified portion of the Premises to any third party on terms
substantially  identical  to those  described  in  Tenant's  Notice,  subject to
Landlord's consent as set forth above. If Tenant does not sublet such portion of
the Premises within 180 days following Landlord's notice to Tenant,  Tenant must
reoffer the Premises to Landlord in accordance with the provisions  hereof prior
to subleasing to a third party.

     14.5 All documents utilized by Tenant to evidence a Transfer are subject to
approval by Landlord. Tenant shall pay Landlord's reasonable expenses, including
reasonable  attorneys' fees, of determining  whether to consent and in reviewing
and approving the documents. Tenant shall provide Landlord with such information
as  Landlord  reasonably  requests  regarding a proposed  Transferee,  including
financial information.

     14.6 If a trustee or debtor in  possession  in  bankruptcy  is  entitled to
assume control over Tenant's  rights under this Lease and assigns such rights to
any third party  notwithstanding  the provisions  hereof, the rent to be paid by
such party shall be  increased  to the current  Base Rent (if greater  than that
being paid for the Premises) which Landlord  charges for comparable space in the
Building as of the date of such third party's occupancy. If Landlord is entitled
under the Bankruptcy Code to "Adequate  Assurance" of future performance of this
Lease, the parties agree that such term includes the following:

     (1) Any assignee must demonstrate to Landlord's  reasonable  satisfaction a
net  worth  (as  defined  in  accordance  with  generally  accepted   accounting
principles consistently applied) at least as large as the net worth of Tenant on
the  Commencement  Date  [increased by 4%,  annually,  for each year  thereafter
through  the date of the  proposed  assignment]  or other  equivalent  financial
capacity.  Tenant's financial condition was a material inducement to Landlord in
executing this Lease.

     (2) The  assignee  must assume and agree to be bound by the  provisions  of
this Lease.

     14.7  Notwithstanding  anything to the contrary  contained  hereinabove but
subject to Section 14.2 and provided that the  conditions of clauses (3) and (5)
of Section 14.1 are met, Tenant may, without obtaining  Landlord's prior written
consent,  assign or sublease all or any portion of the Premises to the following
parties on the following  conditions:  (1) any  subsidiary or affiliate in which
Tenant has, directly or indirectly, an ownership interest of more than 50%; (ii)
any direct or ultimate  parent of Tenant;  (iii) any  subsidiary or affiliate in
which Tenant's  parent owns,  directly or  indirectly,  by means of an ownership
interest  of more than 50%;  or (iv) any  corporation  into which  Tenant may be
merged or consolidated or which purchases all or substantially all of the assets
or stock of Tenant  provided that the resulting  corporation  has a net worth at
least equal to Tenant's net worth as of the date  hereof.  A sale or transfer of
stock in Tenant pursuant to a public offering,  including  publicly traded stock
or  Tenant,  shall be  permitted  without  obtaining  Landlord's  prior  written
consent.  As soon as  practicable  prior to the effective  date of a transaction
permitted   under  this  Section  14.7,   Tenant  will  provide   Landlord  with
documentation  evidencing  such  transaction and such other evidence as Landlord
may reasonably require to establish that such transaction falls within the terms
and  provisions  of this  Section.  Furthermore,  Tenant may allow  employees of
companies  to whom  Tenant is  providing  products or  services  (including  the
maintenance


                                       11
<PAGE>

and  operation of computer  servers for such  companies) or with which Tenant is
collaborating   in  the   development  or  provision  of  products  or  services
(collectively  referred to as  "Collocation  Services")  to work in the Premises
without  Landlord's  consent and without being deemed to have sublet any portion
of the  Premises,  so  long as such  employees  do not  occupy  space  which  is
separated  from that occupied by Tenant by demising walls and the number of such
employees  whose primary place of employment is the Premises does not exceed ten
percent (10%) of the total number of persons regularly occupying the Premises.

     15. DAMAGE TO PROPERTY. Tenant agrees Landlord is not liable for any injury
or damage,  either  proximate  or remote,  occurring  through or caused by fire,
water, steam, or any repairs, alterations,  injury, accident, or any other cause
to the Premises,  to any  furniture,  fixtures,  Tenant  improvements,  or other
personal property of Tenant kept or stored in the Premises, or in other parts of
the  Building  Complex,  whether  by  reason of the  negligence  or  default  of
Landlord,  other occupants,  any other person, or otherwise;  and the keeping or
storing of all property of Tenant in the Premises and Building Complex is at the
sole risk of Tenant.

     16. INDEMNITY TO LANDLORD.

     16.1 Tenant  agrees to  indemnify,  defend,  and hold Landlord and Building
Manager harmless from all liability,  costs, or expenses,  including  attorneys'
fees,  on  account  of damage  to the  person or  property  of any third  party,
including any other tenant in the Building Complex,  to the extent caused by the
negligence or breach of this Lease by the Tenant or Tenant's Agents.

     16.2  Tenant  shall  maintain  throughout  the  Term a  commercial  general
liability  policy,  including  protection  against  death,  personal  injury and
property damage,  issued by an insurance company qualified to do business in the
state in which the Premises  are  located,  with a single limit of not less than
$1,000,000.00.  Such policy shall name Landlord, Building Manager, and Mortgagee
as  additional  insureds,  be primary  to any other  similar  insurance  of such
additional  insureds,  and  provide  that it may not be  cancelled  or  modified
without at least 20 days' prior  notice to Landlord and  Mortgagee.  The minimum
limits of such insurance do not limit the liability of Tenant  hereunder.  Prior
to  occupancy  of the  Premises,  and prior to  expiration  of the  then-current
policy,  Tenant shall deliver  certificates  evidencing that insurance  required
under this Lease is in effect.

     16.3 Landlord  agrees to indemnify,  defend,  and hold Tenant harmless from
all liability,  costs,  or expenses,  including  attorneys'  fees, on account of
damage to the person or property of any third party (excluding  Tenant's Agents)
including any other tenant in the Building Complex,  to the extent caused by the
negligence  or breach of this Lease by Landlord,  subject to the  provisions  of
Section 18.6

     17. SURRENDER AND NOTICE.  Upon the expiration or other termination of this
Lease,  Tenant  shall  immediately  quit and  surrender to Landlord the Premises
broom clean,  in good order and  condition,  ordinary  wear and tear and loss by
fire or other  casualty  excepted,  and Tenant  shall  remove all of its movable
furniture and other effects,  all telephone  cable and related  equipment in the
Building  installed for Tenant, and such Alterations,  as Landlord requires.  If
Tenant fails to timely vacate the Premises as required, Tenant is responsible to
Landlord for all resulting costs and damages of Landlord,  including any amounts
paid to third parties who are delayed in occupying the Premises.

     18. INSURANCE, CASUALTY, AND RESTORATION OF PREMISES.

     18.1 Landlord shall maintain  property  insurance for the Building Complex,
the shell and core of the Building and the Premises in such  amounts,  from such
companies, and on such terms and conditions, sufficient to prevent Landlord from
being a coinsurer under its policy of insurance,  for property loss equal to the
full replacement value of the Building Complex and public liability insurance in
an amount customary for first class office  properties in the Northern  Virginia
area.


                                       12
<PAGE>

     18.2 Tenant shall maintain  throughout the Term insurance coverage at least
as broad as ISO Special Form Coverage  against risks of direct  physical loss or
damage  (commonly known as "all risk") for the full replacement cost of Tenant's
property and betterments in the Premises,  including  tenant finish in excess of
the Initial Tenant Finish.

     18.3 If the Building is damaged by fire or other casualty which renders the
Premises  wholly  untenantable  and the damage is so extensive that an architect
selected by Landlord  certifies in writing to Landlord and Tenant within 30 days
of said  casualty (or such longer  period,  not to exceed a total of 45 days, if
Landlord  is unable to obtain  such  certification  within the 30 day period for
causes beyond Landlord's  reasonable control) that the Premises cannot, with the
exercise of reasonable  diligence,  be made fit for occupancy within 180 working
days from the  happening  thereof,  then,  at the option of  Landlord  or Tenant
exercised  in writing to the other  within 30 days of such  determination,  this
Lease shall  terminate  as of the  occurrence  of such  damage.  In the event of
termination,  Tenant  shall  pay Rent  duly  apportioned  up to the time of such
casualty and forthwith surrender the Premises and all interest.  If Tenant fails
to do so,  Landlord may reenter and take  possession  of the Premises and remove
Tenant.  If, however,  the damage is such that the architect  certifies that the
Premises can be made tenantable  within such 180-day period or neither  Landlord
or Tenant elects to terminate  the Lease despite the extent of damage,  then the
provisions below apply.

     18.4 If the  Premises are damaged by fire or other  casualty  that does not
render it wholly untenantable and require a repair period in excess of 180 days,
Landlord shall with reasonable  promptness  except as hereafter  provided repair
the Premises up to the level of the Initial Tenant Finish.

     18.5 If the Parking Garage or portions of the Building Complex required for
support or operation of the Building is damaged  (though the Premises may not be
affected, or if affected, can be repaired within 180 days) and within 30 days of
said  casualty  (or such  longer  period,  not to exceed a total of 45 days,  if
Landlord  is unable to obtain  such  certification  within the 30 day period for
causes beyond Landlord's reasonable control) Landlord decides not to reconstruct
or rebuild the Building,  then,  notwithstanding anything contained herein, upon
notice to that effect from  Landlord  within said  period,  Tenant shall pay the
Rent apportioned to the later of such casualty or the date that Tenant ceases to
use the Premises,  this Lease shall terminate from the date of such notice,  and
both parties discharged from further  obligations except as otherwise  expressly
provided.

     18.6 Landlord and Tenant waive all rights of recovery against the other and
its  respective  officers,  partners,  members,  agents,  representatives,   and
employees  for loss or  damage  to its real and  personal  property  kept in the
Building  Complex  which is capable of being  insured  against under ISO Special
Form Coverage,  or for loss of business  revenue or extra expense arising out of
or related to the use and occupancy of the Premises. Tenant also waives all such
rights of recovery  against  Building  Manager and Building  Manager  waives all
rights to recovery against Tenant. Each party shall, upon obtaining the property
damage insurance  required by this Lease,  notify the insurance carrier that the
foregoing waiver is contained in this Lease and use reasonable efforts to obtain
an appropriate waiver of subrogation provision in the policies.

     18.7 Rent shall  abate from the later of the date of such  casualty  or the
date that Tenant  ceases to use the Premises and  continuing  until  substantial
completion  during any period of repair and  restoration  up to the level of the
Initial Tenant Finish permitting  occupancy by Tenant,  any recovery by Landlord
under its loss of rent insurance  related to the Premises in the same proportion
that  the  part  of the  Premises  rendered  untenantable  bears  to the  whole;
provided,  however,  if the casualty is the fault of Tenant or Tenant's  agents,
then the Rent will abate  during any such period of repair and  restoration  but
only to the  extent of any  recovery  by  Landlord  under its  rental  insurance
related to the Premises.

     19. CONDEMNATION. If the Premises or substantially all of it or any portion
of the Building  Complex  which  renders the Premises  untenantable  is taken by
right of eminent domain, or by condemnation (which includes a conveyance in lieu
of a taking),  this Lease, at the option of either Landlord or Tenant  exercised
by notice to the other within 30 days after the taking, shall terminate and Rent
shall  be  apportioned  as of the date of the  taking.  Tenant  shall  forthwith
surrender  the Premises and all interest in this Lease,  and, if Tenant fails to
do so, Landlord may reenter and take


                                       13
<PAGE>

possession  of the  Premises.  If less than all the Premises is taken,  Landlord
shall  promptly  repair the  Premises  as nearly as  possible  to its  condition
immediately  prior to the taking,  unless  Landlord  elects not to rebuild under
Section 18.5.  Landlord shall receive the entire award or consideration  for the
taking,  except with respect to the value of Tenant's  improvements and fixtures
and for any separate award made to Tenant for its relocation  expenses  pursuant
to a  separate  independent  action  taken  by  Tenant  against  the  condemning
authority.

     20. DEFAULT BY TENANT.

     20.1 Each of the following events is an "Event of Default":

     (1) Any failure by Tenant to pay Rent on the due date  unless such  failure
is cured within 5 business days after notice by Landlord; however, Tenant is not
entitled to more than 2 notices of delinquent  payments during any calendar year
and, if  thereafter  during such calendar year any Rent is not paid when due, an
Event of Default shall automatically occur;

     (2) Tenant  vacates  (other than  temporary  vacation  during  which period
Tenant is engaged in trying to relet the  Premises) or abandons the Premises (as
evidenced by vacating the Premises  with the intent by Tenant not to be bound by
the terms of the Lease, as evidenced by a breach of any of its other obligations
under the Lease, including the payment of Rent);

     (3) This Lease or Tenant's interest is transferred  whether  voluntarily or
by operation of law except as permitted in Section 14;

     (4) This  Lease  or any part of the  Premises  is taken by  process  of law
against Tenant and is not released within 15 days after a levy;

     (5)  Commencement by Tenant of a proceeding  under any provision of federal
or state law relating to insolvency,  bankruptcy, or reorganization ("Bankruptcy
Proceeding");

     (6)  Commencement  of  a  Bankruptcy   Proceeding  against  Tenant,  unless
dismissed within 60 days after commencement;

     (7) The  insolvency of Tenant or execution by Tenant of an  assignment  for
the benefit of creditors; or the failure of Tenant generally to pay its debts as
they  mature,  or the  occurrence  of any of the  foregoing  with respect to any
Guarantor, if any, of Tenant's obligations;

     (8) The admission in writing by Tenant (or any general partner of Tenant if
Tenant is a  partnership),  that it is unable to pay its debts as they mature or
it is generally not paying its debts as they mature;

     (9)  Tenant  fails  to take  possession  of the  Premises  by the  90th day
following the Commencement Date (which deadline may be extended by delays beyond
the reasonable  control of Tenant,  provided that Tenant is proceeding  with due
diligence to complete the Finish Work and move into the Premises);

     (10)   Tenant   fails  to  perform  any  of  its  other   obligations   and
non-performance  continues  for 30 days  after  notice by  Landlord  or, if such
performance cannot be reasonably had within such 30 day period,  Tenant does not
in good faith  commence  performance  within  such 30 day period and  diligently
proceed  to  completion;  provided,  however,  that if  Tenant's  failure  would
constitute a violation of Applicable  Law and Landlord would be subject to fines
or penalties or use of the Building Complex by another tenant would be adversely
affected,  Tenant's  right to cure  shall not  exceed  the  period  provided  by
Applicable Law;


                                       14
<PAGE>

     (11) Any event which is expressly  defined as or deemed an Event of Default
under Sections 9 and 27.22 of this Lease.

     20.2 Remedies of Landlord. If an Event of Default occurs, Landlord may then
or at any time thereafter, either:

     (1) (a) Without  further  notice  except as required  by  Applicable  Laws,
reenter  and  repossess  the  Premises  or any part and expel  Tenant  and those
claiming  through or under Tenant and remove the effects of both  without  being
deemed  guilty of any manner of trespass  and without  prejudice to any remedies
for arrears of Rent or preceding  breach of this Lease.  Should Landlord reenter
or take possession  pursuant to legal  proceedings or any notice provided for by
Applicable Law, Landlord may, from time to time, without terminating this Lease,
relet the  Premises  or any part,  either  alone or in  conjunction  with  other
portions of the Building  Complex,  in  Landlord's  or Tenant's name but for the
account  of  Tenant,  for such  periods  (which  may be greater or less than the
period which would  otherwise have  constituted  the balance of the Term) and on
such conditions and upon such other terms (which may include concessions of free
rent and alteration  and repair of the Premises) as Landlord,  in its reasonable
discretion,  determines and Landlord may collect the rents therefor. Landlord is
not in any way  responsible or liable for failure to relet the Premises,  or any
part  thereof,  or for any failure to collect any rent due upon such  reletting,
but Landlord shall use commercially  reasonable efforts to mitigate its damages.
If there is other  unleased  space in the Worldgate  complex  (consisting of the
Building,  Plaza I and  building  that  may be built  on the  property  known as
Worldgate Parcel 12; collectively,  the "Worldgate Complex"), Landlord may lease
such other space  without  prejudice to its  remedies  against  Tenant.  No such
reentry  or  repossession  or notice  from  Landlord  shall be  construed  as an
election by Landlord to  terminate  this Lease  unless  specific  notice of such
intention is given Tenant.  Acts of  maintenance or  preservation  or efforts to
relet the Premises or the  appointment of a receiver upon initiative of Landlord
to  protect  Landlord's  interest  under  this  Lease  shall  not  constitute  a
termination of Tenant's  contractual  liability  under this Lease unless written
release of liability is given by Landlord to Tenant. Landlord reserves the right
following any reentry  and/or  reletting to exercise its right to terminate this
Lease by giving  Tenant  notice,  in which  event this Lease will  terminate  as
specified in the notice.

     (b) If Landlord takes possession of the Premises  without  terminating this
Lease,  Tenant  shall  pay  Landlord  (i) the Rent  which  would be  payable  if
repossession  had not  occurred,  less  (ii) the net  proceeds,  if any,  of any
reletting of the Premises after deducting all of Landlord's expenses incurred in
connection with such  reletting,  including all reasonable  repossession  costs,
brokerage commissions,  attorneys' fees, expenses of employees,  alteration, and
repair costs  (collectively  "Reletting  Expenses").  If, in connection with any
reletting,  the new lease term extends  beyond the Term or the premises  covered
thereby include other premises not part of the Premises, a fair apportionment of
the rent received from such reletting and the Reletting  Expenses,  will be made
in determining the net proceeds received from the reletting. In determining such
net proceeds, rent concessions will also be apportioned over the term of the new
lease.  Tenant shall pay such  amounts to Landlord  monthly on the days on which
the Rent  would  have been  payable  if  possession  had not been  retaken,  and
Landlord is entitled to receive the same from Tenant on each such day; or

     (2) Give Tenant notice of  termination  of this Lease on the date specified
and, on such date,  Tenant's right to possession of the Premises shall cease and
the Lease will terminate except as to Tenant's  liability as hereafter  provided
as if the  expiration of the term fixed in such notice were the end of the Term.
If this Lease  terminates  pursuant to this Section,  Tenant  remains  liable to
Landlord  for damages in an amount equal to the Rent which would have been owing
by Tenant for the  balance of the Term had this Lease not  terminated,  less the
net  proceeds,  if any, of reletting of the Premises by Landlord  subsequent  to
termination  after  deducting  Reletting  Expenses.  Landlord  may collect  such
damages  from  Tenant  monthly  on the days on which  the Rent  would  have been
payable if this Lease had not  terminated  and  Landlord  shall be  entitled  to
receive the same from Tenant on each such day.  Alternatively,  if this Lease is
terminated,  Landlord  at its option may  recover  forthwith  against  Tenant as
damages  for loss of the  bargain  and not as a penalty  an amount  equal to the
worth at the time of termination of the excess,  if any, of the Rent reserved in
this Lease for the balance of the Term over the then Reasonable  Rental Value of
the Premises for the same period plus all Reletting Expenses. "Reasonable Rental
Value" is the amount of rent  Landlord can obtain for the  remaining  balance of
the Term.


                                       15
<PAGE>

     20.3 Cumulative Remedies.  Suits to recover Rent and damages may be brought
by Landlord,  from time to time, and nothing herein  requires  Landlord to await
the  date  the  Term  would  expire  had  there  been no  Event  of  Default  or
termination,  as the case may be.  Each  right and remedy  provided  for in this
Lease is cumulative  and  non-exclusive  and in addition to every other right or
remedy  now or  hereafter  existing  at  law  or  equity,  including  suits  for
injunctive  relief and  specific  performance.  The exercise or beginning of the
exercise by Landlord of one or more rights or remedies  shall not  preclude  the
simultaneous  or later  exercise by Landlord of other  rights or  remedies.  All
costs  incurred by  Landlord to collect any Rent and damages or to enforce  this
Lease are also  recoverable  from Tenant.  If any suit is brought  because of an
alleged breach of this Lease,  the prevailing  party is also entitled to recover
from the other  party all  reasonable  attorneys'  fees and  costs  incurred  in
connection therewith.

     20.4 No Waiver. No failure by Landlord to insist upon strict performance of
any provision or to exercise any right or remedy upon a breach  thereof,  and no
acceptance  of full  or  partial  Rent  during  the  continuance  of any  breach
constitutes  a waiver of any such  breach or such  provision,  except by written
instrument executed by Landlord.  No waiver shall affect or alter this Lease but
each  provision  hereof  continues  in effect  with  respect  to any other  then
existing or subsequent breach thereof.

     20.5 Bankruptcy. Nothing contained in this Lease limits Landlord's right to
obtain as liquidated damages in any bankruptcy or similar proceeding the maximum
amount  allowed by law at the time such  damages are to be proven,  whether such
amount is  greater,  equal to, or less than the amounts  recoverable,  either as
damages or Rent, referred to in any of the preceding provisions of this Section.
Notwithstanding  anything  in  this  Section  to the  contrary,  any  proceeding
described  in Section  20.1(5),(6),(7)  and (8) is an Event of Default only when
such proceeding is brought by or against the then holder of the leasehold estate
under this Lease.

     20.6 Late Payment  Charge.  Any Rent not paid within 5 business  days after
the due date shall  thereafter  bear  interest at 5 percentage  points above the
Prime Rate or the highest rate permitted by law, whichever is lower, until paid.
Further,  if such Rent is not paid within 5 business days after  notice,  Tenant
agrees Landlord will incur  additional  administrative  expenses,  the amount of
which will be difficult to determine; Tenant therefore shall also pay Landlord a
late charge for each late  payment of 5% of such  payment.  Any amounts  paid by
Landlord to cure a default of Tenant  which  Landlord  has the right but not the
obligation  to do,  shall,  if not  repaid by Tenant  within 5 days of demand by
Landlord,  thereafter bear interest at 5 percentage  points above the Prime Rate
until paid.  "Prime Rate" means that rate announced by Wells Fargo Bank, N.A. as
its prime rate on the date closest to the date interest commences.

     20.7 Waiver of Jury Trial.  Tenant and Landlord  waive any right to a trial
by jury in suits arising out of or concerning the provisions of this Lease.

     20.8 Self-Help.  Notwithstanding anything in the Lease to the contrary, the
use of force by Landlord or its agents shall not be included  among the remedies
available  to  Landlord.  Landlord  reserves  the right to use  other  self-help
remedies provided that they do not disturb the peace.

     21. DEFAULT BY LANDLORD. In the event of any alleged default on the part of
Landlord,  Tenant shall give notice to Landlord and afford Landlord a reasonable
opportunity to cure such default,  provided  Landlord  commences such cure on or
before the Fifth (5th) day following Tenant's notice and diligently pursues such
cure to completion using commercially  reasonable efforts.  Such notice shall be
ineffective  unless  a copy  is  simultaneously  also  delivered  in the  manner
required  in this  Lease  to any  holder  of a  mortgage  and/or  deed of  trust
affecting   all  or  any  portion  of  the   Building   Complex   (collectively,
"Mortgagee"),  provided  that prior to such notice Tenant has been given written
notice in  accordance  with the notice  provisions of this Lease of the identity
and the address of such  Mortgagee.  Within  such Five (5) day period,  Landlord
shall  provide  written  notice to Tenant of  Landlord's  intended  actions  and
schedule for completion of such cure and regular progress reports  regarding the
same. If Landlord fails to cure such default in accordance with the requirements
set forth above or within 30 days following the notice to Landlord, whichever is
earlier,


                                       16
<PAGE>

then  Mortgagee  shall have an additional 30 days following a second notice from
Tenant or, if such  default  cannot be cured within that time,  such  additional
time as may be necessary to effect a cure,  provided  Mortgagee  commences  such
cure on or  before  the  Fifth  (5th)  day  following  such  second  notice  and
diligently pursues such cure to completion using commercially reasonable efforts
(which  pursuit  shall  include,  without  limitation,   commencing  foreclosure
proceedings  and  seeking  relief in any  applicable  bankruptcy  or  insolvency
proceedings, if necessary to effect such cure). If Landlord fails to cure within
Landlord's cure period,  Tenant shall be entitled to relief against Landlord for
such  default  (other  than  termination  of  the  Lease)  for  so  long  as the
Mortgagee's cure period remains in effect.  If such default involves  Landlord's
failure to make repairs,  provide essential  services,  pay utility bills as are
required under this Lease or any other circumstance that would materially impair
Tenant's  ability to continue  operating  its business on and from the Premises,
then, if such default or failure is not cured within Five (5) days following the
date of such notice to Landlord, Tenant also shall have the right (but shall not
be  obligated  to) to  undertake  such repairs (in such manner as to not to void
applicable  warranties),  provide  services or pay such bills or take such other
actions as are  reasonably  required  to enable  Tenant to avoid  such  material
impairment  and to continue  operating  its business  activities on and from the
Premises  (consistent  with the Permitted Uses under this Lease),  provided that
such  undertakings  by Tenant do not  materially  interfere with such actions by
Landlord to effect a cure as are (1) actually  being  undertaken  by Landlord at
such time and (2) as are equally likely and  expeditious in effecting a complete
cure as those  which  could be taken or are  proposed to be taken by Tenant and,
further provided,  that Tenant's  undertakings to effect a cure do not result in
any permanent  material  damage to the Building or Building  Complex.  As to all
such  undertakings by Tenant,  Landlord shall reimburse Tenant within 30 days of
receipt of Tenant's  invoice the full  amount of such  reasonable  out-of-pocket
costs and  expenses  incurred  by Tenant;  provided,  however,  that if Landlord
disputes  that such default  exists or disputes the  reasonableness  of all or a
portion of the amount to be paid, by notice to Tenant prior to the expiration of
the 30 day period,  then  Landlord  shall have no  obligation  to pay the amount
disputed  until  such  dispute is  determined  by final  decision  of a court or
agreement  of the parties.  If any such repairs will affect the HVAC,  plumbing,
electrical or mechanical  systems of the Building (the "Building Systems "), the
structural  integrity  of  the  Building,  or  the  exterior  appearance  of the
Building,  Tenant  shall use only  those  contractors  used by  Landlord  in the
Building for work on the  Building  Systems,  or its  structure,  provided  that
Landlord  provides Tenant (upon Tenant's  request) with notice  identifying such
contractors  and  any  changes  to the  list of such  contractors,  unless  such
contractors  are  unwilling  or unable to perform  such work or the cost of such
work is not  competitive,  in which event Tenant may utilize the services of any
other qualified  contractors which normally and regularly  performs similar work
on  comparable  buildings.  To the extent any sum thus  reimbursed  to Tenant by
Landlord  represents  an amount that would have been  included in the  Operating
Expenses  of the  Building if paid by  Landlord  to perform  the  obligation  in
question,  Landlord  shall be entitled to include in Operating  Expenses the sum
reimbursed to Tenant.  Tenant's sole additional  remedy will be equitable relief
or actual damages but in no event is Landlord or any Mortgagee  responsible  for
consequential  damages  or lost  profit  incurred  by  Tenant as a result of any
default  by  Landlord.  If  a  Mortgagee,  or  transferee  under  such  Mortgage
(hereafter defined),  succeeds to Landlord's interest as a result of foreclosure
or otherwise,  such party shall not be: (i) liable for any default,  nor subject
to any setoff or defenses  that Tenant may have  against  Landlord  except for a
reimbursement  obligation  arising under this Section as to which such Mortgagee
has been given  notice and the  opportunity  to  dispute as  provided  herein or
except for  obligations  arising or continuing  after the date such Mortgagee or
transferee  succeeds  to  Landlord's  interest;  (ii)  bound  by  any  amendment
(including an agreement for early  termination)  without its consent made at any
time after notice to Tenant that such Mortgage requires such consent;  and (iii)
bound by payment of Rent in advance for more than 30 days.  Tenant agrees to pay
Rent (and will receive  credit under this Lease) as directed in any  Mortgagee's
notice of  Landlord's  default  under the Mortgage  reciting  that  Mortgagee is
entitled to collect Rent.  The terms of Section 7 of this Lease shall be subject
to the terms of this Section.

     22. SUBORDINATION AND ATTORNMENT.

     22.1 This Lease at Landlord's  option will be  subordinate to any mortgage,
deed of trust and related  documents  now or hereafter  placed upon the Building
Complex  (including  all  advances  made  thereunder),  and to  all  amendments,
renewals,  replacements,  or restatements  thereof  (collectively,  "Mortgage").
Tenant  agrees  that no  documentation  other  than this  Lease is  required  to
evidence such subordination, provided, however, that the subordination by Tenant
to any such future mortgage, deed of trust or related documents shall be subject
to Tenant obtaining a non-


                                       17
<PAGE>

disturbance  agreement,  on such lender's standard form agreement,  with changes
are Tenant may  reasonably  require (to the extent such  changes are  consistent
with  provisions  in forms  customarily  executed  by  credit-worthy  full-floor
tenants)  whereby  such lender  agrees,  provided  Tenant is not then in default
under  this  Lease,  that  Tenant's  occupancy  of the  Premises  and rights and
privileges  under this Lease shall not be  disturbed  or impaired in  connection
with any proceeding to enforce or foreclose any such mortgage,  trust  indenture
or other lien and if such party  succeeds to the interests of Landlord by reason
of such proceedings or conveyance in lieu thereof, Tenant shall attorn hereunder
directly to such party;  provided,  however,  such party shall not be (i) liable
for any act or omission of any prior  landlord or (ii) subject to any offsets or
defenses which Tenant might have against any prior landlord,  including Landlord
(but such  limitation  shall not relieve such party from the  responsibility  to
perform the obligations as successor to Landlord applicable during its period of
ownership);  or (iii) bound by any rental  which Tenant might have paid for more
than one (1)  month in  advance  to any  prior  landlord;  or (iv)  bound by any
amendment or modification of the Lease made without its consent.

     22.2 If any Mortgagee elects to have this Lease superior to the lien of its
Mortgage  and gives  notice to Tenant,  this Lease will be deemed  prior to such
Mortgage  whether  this Lease is dated prior or  subsequent  to the date of such
Mortgage or the date of recording thereof.

     22.3 In confirmation of subordination or superior position, as the case may
be, Tenant will execute such documents as may be required by Mortgagee and if it
fails to do so within 10 days after demand,  Tenant hereby irrevocably  appoints
Landlord as Tenant's attorney-in-fact and in Tenant's name, place, and stead, to
do so.

     22.4 Tenant hereby attorns to all successor owners of the Building, whether
such ownership is acquired by sale, foreclosure of a Mortgage, or otherwise.

     22.5 Upon the  execution  hereof,  Tenant and  Landlord's  Mortgagee  shall
execute the form of  nondisturbance  agreement  in the form  attached  hereto as
EXHIBIT J and thereafter Landlord promptly shall provide Tenant such document as
executed by Landlord's Mortgagee.

     23. REMOVAL OF TENANT'S PROPERTY.

     23.1 All movable personal  property of Tenant not removed from the Premises
upon vacation,  abandonment,  or termination of this Lease shall be conclusively
deemed  abandoned and may be sold, or otherwise  disposed of by Landlord without
notice to Tenant and without obligation to account;  Tenant shall pay Landlord's
expenses in connection with such disposition.

     23.2 Tenant shall have the right to collaterally  assign Tenant's  interest
in its furniture,  fixtures,  and equipment that are not considered  part of the
Premises; Landlord agrees to execute documents, subject to Landlord's reasonable
approval,  evidencing  that Landlord does not have a  pre-existing  lien on such
personal property.

     24.  HOLDING  OVER:  TENANCY  MONTH-TO-MONTH.  If, after the  expiration or
termination of this Lease,  Tenant remains in possession of the Premises without
a  written  agreement  as to such  holding  over and  continues  to pay rent and
Landlord  accepts such rent, such  possession is a tenancy from  month-to-month,
subject to all provisions hereof but at a monthly rent equivalent to 150% of the
monthly Rent paid by Tenant immediately prior to such expiration or termination.
Rent shall  continue to be payable in advance on the first day of each  calendar
month. Such tenancy may be terminated by either party upon 10 days' notice prior
to the end of any monthly period. Nothing contained herein obligates Landlord to
accept rent tendered after the expiration of the Term or relieves  Tenant of its
liability under Section 17.

     25. PAYMENTS AFTER  TERMINATION.  No payments by Tenant after expiration or
termination  of this Lease or after any notice  (other than a demand for payment
of money) by  Landlord to Tenant  reinstates,  continues,  extends the Term,  or
affects  any  notice  given to  Tenant  prior to such  payments.  After  notice,
commencement of a suit, or


                                       18
<PAGE>

final  judgment  granting  Landlord  possession  of the  Premises,  Landlord may
collect  any amounts  due or  otherwise  exercise  Landlord's  remedies  without
waiving any notice or affecting any suit or judgment.

     26.  STATEMENT OF  PERFORMANCE.  Tenant and Landlord agree at any time upon
not less than 10  business  days'  written  notice to execute and deliver to the
requesting  party a written  statement  certifying that this Lease is unmodified
and in full force and effect  (or,  if there have been  modifications,  that the
same is in full force and effect as modified  stating the  modifications);  that
there have been no  defaults  by  Landlord or Tenant and no event which with the
giving of notice or passage of time, or both,  would  constitute  such a default
(or, if there have been defaults, setting forth the nature thereof); the date to
which Rent has been paid in advance and such other  information  relating to the
Lease as the requesting party requests. Such statement from Tenant may be relied
upon by a prospective purchaser of Landlord's interest or Mortgagee. The failure
of either party when  requested to timely  deliver such  statement is conclusive
upon the failing party that:  (i) this Lease is in full force and effect without
modification  except as may be represented by the requesting  party;  (ii) there
are no uncured  defaults in the requesting  party's  performance;  and (iii) not
more than 1 month's Rent has been paid in advance.  Upon request, the certifying
party will furnish Landlord an appropriate certificate confirming that the party
signing the statement is authorized to do so.

     27. MISCELLANEOUS.

     27.1 Transfer by Landlord.  The term "Landlord" means so far as obligations
of  Landlord  are  concerned,  only  the  owner of the  Building  at the time in
question and, if any transfer of the title occurs, Landlord herein named (and in
the  case of any  subsequent  transfers,  the  then  grantor)  is  automatically
released  from and after the date of such  transfer of all liability as respects
performance of any obligations of Landlord thereafter to be performed. Any funds
in Landlord's possession at the time of transfer in which Tenant has an interest
will be turned over to the  grantee  and any amount  then due Tenant  under this
Lease will be paid to Tenant.

     27.2 No Merger.  The termination or mutual  cancellation of this Lease will
not work a merger,  and such  termination or cancellation  will at the option of
Landlord either terminate all subleases or operate as an automatic assignment to
Landlord of such subleases.

     27.3  Common  Area Use.  Landlord  may use any of the Common  Areas for the
purposes of completing or making  repairs or  alterations  in any portion of the
Building Complex, subject to the provisions of Section 11.

     27.4  Independent  Covenants.  This Lease is to be  construed as though the
covenants  between  Landlord and Tenant are  independent  and not  dependent and
Tenant is not  entitled to any setoff of the Rent  against  Landlord if Landlord
fails to perform its  obligations;  provided,  however,  the foregoing  does not
impair  Tenant's  right to commence a separate  suit  against  Landlord  for any
default by Landlord so long as Tenant complies with Section 21.

     27.5 Validity of  Provisions.  If any provision is invalid under present or
future laws,  then it is agreed that the remainder of this Lease is not affected
and that in lieu of each provision that is invalid,  there will be added as part
of this  Lease a  provision  as  similar  to such  invalid  provision  as may be
possible and is valid and enforceable.

     27.6 Captions.  The caption of each Section is added for  convenience  only
and has no effect in the construction of any provision of this Lease.

     27.7  Construction.  The  parties  waive  any  rule  of  construction  that
ambiguities are to be resolved  against the drafting party.  Any words following
the words "include,"  "including," "such as," "for example," or similar words or
phrases shall be illustrative only and are not intended to be exclusive, whether
or not language of non-limitation is used.


                                       19
<PAGE>

     27.8 Applicability.  Except as otherwise  provided,  the provisions of this
Lease are  applicable  to and binding upon  Landlord's  and Tenant's  respective
heirs,  successors  and  assigns.  Such  provisions  are also  considered  to be
covenants running with the land to the fullest extent permitted by law.

     27.9  Authority.  Tenant  and the party  executing  this Lease on behalf of
Tenant represent to Landlord that such party is authorized to do so by requisite
action of Tenant and agree,  upon  request,  to deliver  Landlord a  resolution,
similar document, or opinion of counsel to that effect.

     27.10  Severability.  If there is more than one party  which is the Tenant,
the obligations imposed upon Tenant are joint and several.

     27.11  Acceptance  of Keys,  Rent or  Surrender.  No act of Landlord or its
representatives  during the Term,  including any agreement to accept a surrender
of the Premises or amend this Lease,  is binding on Landlord  unless such act is
by a partner,  member or officer of Landlord, as the case may be, or other party
designated  in writing by Landlord as authorized to act. The delivery of keys to
Landlord or its representatives  will not operate as a termination of this Lease
or a surrender of the Premises. No payment by Tenant of a lesser amount than the
entire  Rent owing is other than on account of such Rent nor is any  endorsement
or  statement  on any  check  or  letter  accompanying  payment  an  accord  and
satisfaction.  Landlord may accept payment without prejudice to Landlord's right
to recover the balance or pursue any other remedy available to Landlord.

     27.12 Building Name and Size.  Landlord may change the name of the Building
and as it relates to the Building  Complex other than the  Building:  change the
name,  increase the size by adding  additional  real property,  construct  other
buildings  or  improvements,  change  the  location  and/or  character,  or make
alterations  or  additions  subject  to  the  provisions  of  Section  11.1.  If
additional  buildings are  constructed  or the size is  increased,  Landlord and
Tenant shall execute an amendment that incorporates any necessary  modifications
to  Tenant's  Pro Rata  Share.  Tenant may not use the  Building's  name for any
purpose other than as part of its business address.

     27.13 Diminution of View.  Tenant agrees that no diminution of light,  air,
or view from the Building  entitles  Tenant to any  reduction of Rent under this
Lease,  results in any  liability  of Landlord,  or in any way affects  Tenant's
obligations.

     27.14  Limitation  of Liability.  Notwithstanding  anything to the contrary
contained in this Lease,  Landlord's liability is limited to Landlord's interest
in the Building and Landlord  shall never be  personally  liable for recovery of
any judgment.

     27.15  Non-Reliance.  Tenant  confirms it has not relied on any statements,
representations,  or warranties by Landlord or its representatives except as set
forth herein.

     27.16 Written  Modification.  No amendment or modification of this Lease is
valid or binding unless in writing and executed by the parties.

     27.17 Lender's  Requirements.  Tenant will make such  modifications to this
Lease as may  hereafter  be  required  to  conform  to any  lender's  reasonable
requirements, so long as such modifications do not increase Tenant's obligations
or materially alter its rights, as reasonably determined by Tenant.

     27.18  Effectiveness.  Submission of this  instrument  for  examination  or
signature by Tenant does not  constitute a reservation of or option to lease and
it is not effective unless and until execution and delivery by both Landlord and
Tenant.


                                       20
<PAGE>

     27.19  Survival.  This Lease,  notwithstanding  expiration or  termination,
continues in effect as to any  provisions  requiring  observance or  performance
subsequent to termination or expiration.

     27.20 Time of Essence. Time is of the essence herein.

     27.21 Rules and Regulations.  If rules and regulations are attached hereto,
they are a part of this Lease and Tenant agrees that Tenant and Tenant's  Agents
shall at all times abide by such rules and regulations.

     27.22 Recording.  Tenant will not record this Lease. Recording of the Lease
by or on behalf of Tenant is an Event of Default.

     27.23 Consent.  Where either  party's  consent is required under the Lease,
such consent shall not be unreasonably withheld, delayed or conditioned,  except
as expressly provided.

     28. AUTHORITIES FOR ACTION AND NOTICE.

     28.1  Unless  otherwise  provided,  Landlord  may  act  through  Landlord's
Building Manager or other designated representatives from time to time.

     28.2 All notices or other communications required or desired to be given to
Landlord must be in writing, addressed as set forth in Section 1.10 and shall be
deemed  received  when:  (i) delivered  personally to any officer,  partner,  or
member of Landlord (depending upon the nature of Landlord) or the manager of the
Building (the "Building  Manager")  whose office is in the Building,  or (ii) if
deposited in the United States mail,  postage prepaid,  certified or registered,
return receipt requested, when such notice is received or receipt is refused, or
(iii) if  deposited  with a  nationally  recognized  courier  service  providing
confirmation of receipt,  when such notice is received or receipt is refused, or
(iv) if sent by facsimile  transmission,  when received and oral confirmation by
telephone  of such  receipt  has been  given by the  recipient.  All  notices or
communications  required  or desired to be given to Tenant  must be in  writing,
addressed  as set  forth in  Section  1.13 and shall be  deemed  received  when:
(i) delivered  personally  to  any  officer,  partner,  or  member  of  Landlord
(depending  upon the nature of  Landlord)  or the manager of the  Building  (the
"Building Manager") whose office is in the Building, or (ii) if deposited in the
United States mail,  postage  prepaid,  certified or registered,  return receipt
requested,  when such  notice is  received  or receipt is  refused,  or (iii) if
deposited with a nationally recognized courier service providing confirmation of
receipt,  when such notice is received or receipt is refused, or (iv) if sent by
facsimile transmission, when received and oral confirmation by telephone of such
receipt has been given by the  recipient.  Either party may designate in writing
served as above  provided a different  address to which  notice is to be mailed.
The foregoing does not prohibit notice from being given as provided in the rules
of civil  procedure,  as amended  from time to time,  for the state in which the
Real Property is located.

     29.  PARKING.  Landlord  shall  control  parking in the  Parking  Garage by
Tenant's  employees  and employees of tenants in Plaza II by issuance of parking
passes;  Landlord will make  available the number of parking spaces set forth in
Section 1.9 without  charge for parking by Tenant's  employees by issuing passes
to employees designated by Tenant for the applicable number of spaces.  Landlord
shall have the right to control or limit  parking by visitors to the Building in
a manner  consistent  with  policies  at similar  first-class  buildings  in the
suburban  northern  Virginia area; the visitor spaces for Tenant shall be in the
surface spaces adjacent to the entry to the Building,  as shown on the site plan
attached  as  EXHIBIT  H (which  spaces  shall be a  portion  of the 322  spaces
allocated to Tenant in  accordance  with Section 1.9)  designated  by signage as
visitor  parking  spaces for Tenant's  visitors only (but Landlord shall have no
obligation  to police the use of such visitor  spaces);  the  remaining  parking
spaces  shall be in the  parking  garage  located in the lower level and the 1st
through 4th floors of the  Building  and of the Plaza I Building  (the  "Parking
Garage") and in surface  parking  spaces in the Building  Complex as depicted on
the  attached  EXHIBIT  H.  All  Tenant's  parking  spaces  shall be in and out,
non-assigned,  however, at Tenant's request, Landlord shall label by signage all
spaces  allocated to Tenant (other than  handicapped  spaces) as depicted on the
attached  EXHIBIT H and Tenant  shall have the right to  install  control  gates
limiting


                                       21
<PAGE>

access to Tenant's  parking  spaces on parking level four (subject to Landlord's
reasonable  approval  of such system and  subject to the  provisions  of Section
7.1);  the costs of such  signage  and  control  gates  shall be paid by Tenant.
Notwithstanding the above, Landlord's inability to make such spaces available at
any time for  reasons  beyond  Landlord's  reasonable  control is not a material
breach by Landlord of its obligations  hereunder and Tenant has no rights to use
the parking garage except as provided in this Section.  If Landlord is unable to
make all such spaces available for reasons beyond Landlord's reasonable control,
Landlord  shall  take  reasonable  steps to make all such  spaces  available  as
provided herein.  All vehicles parked in the parking facilities and the personal
property  therein shall be at the sole risk of Tenant,  Tenant's  Agents and the
users of such spaces and  Landlord  shall have no  liability  for loss or damage
thereto for whatever cause.

     30. SUBSTITUTE PREMISES. INTENTIONALLY OMITTED.

     31.  BROKERAGE.  Tenant  represents  it has not  employed  any broker  with
respect to this Lease and has no knowledge of any broker's  involvement  in this
transaction  except those listed in Sections  1.15 and 1.16  (collectively,  the
"Brokers").  Tenant shall  indemnify  Landlord  against any expense  incurred by
Landlord as a result of any claim for  commissions  or fees by any other broker,
finder, or agent, whether or not meritorious, employed by Tenant or claiming by,
through, or under Tenant, other than the Brokers.  Tenant acknowledges  Landlord
is not liable for any  representations  by the Brokers  regarding  the Premises,
Building,  Building Complex, or this Lease.  Landlord represents that it has not
employed  any broker  with  respect to this  Lease and has no  knowledge  of any
broker's involvement in this transaction except those listed in Section 1.15 and
1.16 (collectively,  the "Brokers"). Landlord shall indemnify Tenant against any
expense  incurred by Tenant as a result of any claim for  commissions or fees by
any other broker,  finder,  or agent,  whether or not  meritorious,  employed by
Landlord or claiming by,  through,  or under  Landlord,  other than the Brokers.
Landlord  shall pay  commissions  due  Brokers  in  connection  with this  Lease
pursuant to separate written agreement

     32.  COUNTERPARTS.  This Lease may be executed in two or more counterparts,
each of which  shall be  deemed an  original,  but all of which  together  shall
constitute one and the same instrument.  Any one or more  counterpart  signature
pages may be removed  from one  counterpart  of the Lease and annexed to another
counterpart  of the  Lease to form a  completely  executed  original  instrument
without impairing the legal effect of the signature thereon.

     33.  ADDENDUM/EXHIBITS.  Any Addenda and/or Exhibits referred to herein and
attached hereto are incorporated herein by reference.

     IN WITNESS WHEREOF,  the parties have executed this Lease as of the day and
year first above written and it is effective  upon delivery of a  fully-executed
copy to Tenant.


                                       22
<PAGE>

SAVVIS COMMUNICATIONS  CORPORATION,         WGP  ASSOCIATES,  LLC,  a  Virginia
a Missouri corporation                      limited liability company

                                            By:/s/ Greg Pohle
                                               -----------------
By:/s/ David J. Frear                       Authorized Signatory
   -----------------------                  "Landlord"
Print Name: David J. Frear
           ---------------
Print Title: Executive Vice President
            -------------------------
             Chief Financial Officer

ATTEST:

By:/s/ Steven M. Gallant
   ---------------------
Print Name: Steven M. Gallant
            -----------------
Print Title: Vice President
            -----------------
                  "Tenant"


                                       23
<PAGE>

                                    ADDENDUM

     THIS  ADDENDUM is to that  certain  lease  agreement  (the  "Lease") by and
between WGP ASSOCIATES,  LLC, a Virginia limited liability company ("Landlord"),
and SAVVIS COMMUNICATIONS  CORPORATION, a Missouri corporation ("Tenant"),  with
respect to  approximately  80,580 rentable square feet of space (the "Premises")
in the Building.  In the event of any conflict  between the terms and provisions
of the  Lease  and the  terms and  provisions  of this  Addendum,  the terms and
provisions of this Addendum shall control.

     1. Landlord  grants  Tenant an option (the  "Option") to extend the term of
the Lease for one (1) additional term of five (5) years (the "Option Term"). The
Option applies only to the Premises and is on the following conditions:

     A. Notice of Tenant's  interest in  exercising  the Option must be given to
Landlord  no  earlier  than 12 months  and no later  than 9 months  prior to the
Expiration  Date  ("Tenant's  Notice").  Not later than  thirty  (30) days after
receiving  Tenant's  Notice,  Landlord  will  notify  Tenant  of the  Base  Rent
applicable  during the  Option  Term in  accordance  with  subparagraph  E below
("Landlord's Notice").

     B.  Tenant  shall have 15 days  following  Tenant's  receipt of  Landlord's
Notice  within  which to exercise  the Option for the Option Term by  delivering
written  notice of such  exercise to Landlord at the Base Rent,  allowances  and
concessions, if any, set forth in Landlord's Notice or delivering notice of such
exercise but reserving the right to final  determination  of the Base Rent to be
paid in accordance with  subparagraphs E below ("Tenant's  Dispute Notice").  If
Tenant timely  exercises the Option for the  respective  Option Term,  the Lease
shall be deemed  extended and  thereafter the parties shall execute an amendment
to the Lease setting forth the extension for the Option Term and the rental rate
applicable  upon  determination  of the Base Rent  applicable in accordance with
subparagraph E below.

     C.  Unless  Landlord  is  timely  notified  by Tenant  in  accordance  with
subparagraphs A and B above, it will be conclusively  deemed that Tenant has not
exercised the Option and the Lease will expire in  accordance  with its terms on
the Expiration Date.

     D. Tenant's  rights  pursuant to this  Paragraph are personal to Tenant and
may not be assigned.  Tenant's right to exercise the Option is  conditioned  on:
(i)  Tenant  not  being in  default  at the time of  exercise  or at the time of
commencement  of the Option  Term;  (ii) Tenant not having  subleased or vacated
more than 33% of the Premises or assigned its interest under the Lease as of the
commencement  of the Option Term; and (iii) Tenant having the financial  ability
to perform its  obligations  under the Option Term.  Upon an  assignment  of the
Lease, this Paragraph is null and void.

     E. Following delivery of Tenant's Dispute Notice, Landlord and Tenant shall
promptly initiate  negotiations to determine a mutually acceptable Base Rent. If
the parties  mutually agree upon a Base Rent rate, such agreed rate shall be the
Base Rent rate applicable during the Option Term. If the parties have not agreed
upon the  terms as of the 20th day after the date of  Tenant's  Dispute  Notice,
then Landlord and Tenant shall,  within thirty (30) days after Tenant's delivery
of Tenant's Dispute Notice, agree upon a qualified commercial real estate broker
of good reputation,  having at least five (5) years'  experience in the northern
Virginia  real estate  market;  if  Landlord  and Tenant  cannot  agree upon the
broker, then they shall each select,  within the foregoing  thirty-day period, a
real estate broker who meets the above  qualifications and together such brokers
will then  select as the  arbitrator  a real  estate  broker who meets the above
qualifications (the broker selected shall be deemed the "Arbitrator" hereunder).
Within ten (10)) days of selection of the  Arbitrator,  Landlord and Tenant each
shall state, in writing,  their  determination  of the Prevailing  Market Rental
Rate  supported by the reasons  therefor and shall make  counterpart  copies for
each other and the Arbitrator, under an arrangement for simultaneous exchange of
the  determinations.  The Arbitrator will review each party's declaration of the
Prevailing  Market  Rental  Rate and  select  the one which he  determines  most
accurately  reflects such  Arbitrator's  determination of the Prevailing  Market
Rental Rate.  The  Arbitrator  shall have no right to propose a middle ground or
any


                                        1
<PAGE>

modifications of either of the two proposed  resolutions.  The Base Rent to paid
during the Option Term shall be the Prevailing  Market Rental Rate so determined
and Tenant shall have the right to receive the  allowance  and  concessions,  if
any, set forth in  Landlord's  Notice.  The costs  incurred in  connection  with
engaging the  Arbitrator  shall be shared  equally by Landlord  and Tenant,  and
shall be determined at the time the Arbitrator is selected. For purposes of this
Paragraph, Prevailing Market Rental Rate shall mean the annual amount per square
foot (including the then-current Operating Expenses) that a willing tenant would
pay and a willing landlord would accept following arms-length  negotiations with
respect to an "Assumed  Lease" (as defined below) under the  circumstances  then
obtaining.  "Assumed  Lease" means (i) a lease or renewal  having a commencement
date within 6 months of Tenant's Notice for space of approximately the same size
as the  Premises of the  Building or a  "Comparable  Building,"  as  hereinafter
defined,  located in a portion of the Building or such Comparable Building,  and
with a view and floor  height  similar to the portion of the  Premises for which
Prevailing Market Rental Rate is being determined, for a term equal in length to
the Option Term;  (ii)  assuming  that a real estate  commission is payable with
respect to such lease to the extent a  third-party  commission  with  respect to
extension is agreed or  obligated to be paid by Landlord;  and (iii) taking into
consideration  and making  adjustment  to  reflect  allowances  and  concessions
provided  in  Landlord's  Notice,  if any,  and the  use of the  Base  Operating
Expenses provided in Section 1.5 during the Option Term.  "Comparable  Building"
shall mean any existing building or building hereafter constructed in the Dulles
corridor of northern Virginia which is of a size, location, quality and prestige
comparable  to, and with a size and  efficiency of floor plate,  amenities,  and
with tenants of a stature reasonably comparable with the Building, provided that
appropriate  adjustments  shall be made to adjust for  differences  in the size,
location,  age,  efficiency  of  floorplate,  and  quality  between  such  other
buildings and the Building.

     F. After exercise,  or failure to exercise the Option, Tenant shall have no
further rights to extend the Term.

     2. In accordance with the Work Letter,  as part of the Finish Work,  Tenant
shall have the right to have signage  installed on a monument to be  constructed
by Landlord,  which  monument  shall be  constructed  at Landlord's  cost;  such
signage  shall be subject to  approval by  Landlord  of the exact  location  and
details,  which  approval  shall not be  unreasonably  withheld,  conditioned or
delayed.  Further,  the monument and Tenant's signage on the monument is subject
to  approval  under  Applicable  Law and under  the  declaration  of  protective
covenants  applicable  to the Real Property  (the  "Declaration"),  all of which
approvals shall be diligently pursued by Landlord. The monument,  which shall be
designed  and  constructed  by Landlord at  Landlord's  cost,  is intended for a
building  name/address  identifier for the entire 4 tower Worldgate Plaza I, II,
III,  and IV complex and for tenants of the  complex,  and  notwithstanding  the
above, is not exclusively for Tenant's signage;  however,  Tenant shall have the
right to use 25% of such monument  signage area;  the monument shall not be used
for Tenant's signage if only the Building  name/address  identifier is permitted
on such monument under the  Declaration  and  Applicable  Law. The costs for the
design,  fabrication and installation of such Tenant's signage shall be borne by
Tenant  (subject to the allowance  provisions  of the Work Letter).  Tenant will
bear the costs of removal of any signage at the termination or expiration of the
Lease,  including  restoring or repairing damages to the monument caused by such
removal to the condition at the time of installation.  In addition,  if Landlord
is required at any time to remove any signage,  including any approved  signage,
due to any Applicable Law or if Tenant elects to remove or change the signage at
any time, Tenant shall bear the costs of such change or removal.  Tenant will be
responsible  at its cost to maintain its signage in  reasonably  good  condition
acceptable  to Landlord at  Landlord's  reasonable  discretion;  Landlord  shall
maintain  the  monument  as part of the  Common  Areas and shall  require  other
tenants to maintain  their  respective  signage.  In  addition  to the  monument
signage, Tenant shall have the right to install a corporate  identification sign
on the exterior of the Building facing the Dulles  Toll/Access  Roads out of the
Allowance  or, if there is no balance of the  Allowance  available,  at Tenant's
expense.  Such  Building  signage shall be subject to approval  (including  with
respect to  location,  style,  size,  material,  and method of  application)  by
Landlord,  which approval  shall not be  unreasonably  withheld,  conditioned or
delayed,  and under  Applicable Laws and under the Declaration  (which approvals
shall be  diligently  pursued by  Landlord).  Tenant shall not  otherwise  affix
signage to the outside of the  Building  and no signage  shall be affixed to the
inside of the Building that is visible outside the Building without the approval
of Landlord,  which approval shall not be unreasonably  withheld or delayed. The
rights  granted to Tenant  pursuant to this Paragraph are personal to Tenant and
any assignees (except an assignee  permitted under Section 14.7 of the Lease) or


                                        2
<PAGE>

subtenants  of Tenant have no rights under this  Section.  Tenant shall have the
right to erect temporary construction  identification  signage, at Tenant's sole
cost and expense,  during the period prior to the Commencement  Date identifying
the Building as Tenant's future  location,  subject to approval  (including with
respect to  location,  style,  size,  material,  and method of  application)  by
Landlord  which  approval  shall not be  unreasonably  withheld,  conditioned or
delayed,  and approval under  Applicable Laws and under the  Declaration  (which
approvals shall be diligently pursued by Landlord).

     3.  During  the  Term,  Tenant  shall  have a right  to use the roof of the
Building for the purpose of installing,  maintaining and operating the following
described  equipment  on  a  portion  of  the  roof  of  the  Building  ("Roof")
anticipated  to be within the area  labeled  "(1)" on the roof plan  attached as
part of EXHIBIT I, with the actual  location to be  designated  by Landlord,  in
Landlord's reasonable discretion ("Roof Space"): (1) chillers, as referred to on
EXHIBIT 5 to the Work Letter, to service equipment in the Premises  ("Chillers")
and (2) non-penetrating (or alternative attachment methods approved by Landlord)
microwave/satellite  dishes,  not to exceed  approximately one meter in diameter
(or such  larger  dimensions  as shall be subject to  Landlord's  prior  written
consent, not to be unreasonably withheld, conditioned or delayed) (the "Dishes")
and   antennae   not  to  exceed   approximately   one  meter  in  height   (the
"Antennae")(the  foregoing  height and size  limitations  shall be  exclusive of
dimensions of any customary  pedestals,  platforms,  supports or other  mounting
devices associated with such equipment), and (3) screening, equipment, conduits,
cables and  materials  to be located on the Roof Space or in other  parts of the
Building  serving  the items  listed in clauses (1) and (2)  (collectively,  the
"Related Equipment") in accordance with the terms of this Section.  Tenant shall
have the  right to  locate  on the Roof  additional  equipment  associated  with
Tenant's  use of the  Premises  for the  Permitted  Uses,  provided  that Tenant
obtains  Landlord's  prior  consent  (which  consent  shall not be  unreasonably
withheld);  if  approved,  such  additional  equipment  shall be  subject to the
provisions  of  this  Paragraph  and  deemed  Related  Equipment  hereunder.  In
designating  the actual location of the Chillers,  Dishes,  Antennae and Related
Equipment,  Landlord shall use reasonable  efforts to accommodate  line of site,
avoidance of interference  and other technical  requirements to be satisfied for
the full functionality of such Chillers, Dishes, Antennae and Related Equipment.
In the event that the Roof Space is unsuitable for any such Dishes, Antennae and
Related  Equipment or cannot perform  according to Tenant's  requirements on the
Roof Space, Landlord shall reasonably consent to the use by Tenant of roof space
on  another  building  within  the  Building  Complex,  provided  that  space is
available  on such roof and the use,  location  and  equipment  is  approved  in
accordance with  Applicable  Laws and is otherwise  permitted in accordance with
the Declaration and agreements Landlord may have entered into with third parties
as of such time,  and  Tenant  agrees to be bound by the  requirements  to which
third party  tenants  are  required  to be bound  under  subsection  D, below in
respect  of their  use of the Roof  Space.  All costs and  expenses  related  to
installation  (including  costs of acquiring  any required  permits  therefor or
approvals  under the  Declaration),  maintenance,  operation  and removal of the
Chillers,  Dishes,  Antennae and Related  Equipment shall be borne by Tenant but
Tenant shall not pay any additional fee or Rent for use of the Chillers,  Dishes
Antennae and the Related Equipment under this Lease.

     A.  Tenant  will not use the Roof for any  purpose  other than  installing,
maintaining and operating the Chillers,  Dishes,  Antennae and Related Equipment
for  Tenant's  business  operations,  but shall not have any right to license or
otherwise  provide use of the Chillers,  Dishes,  Antennae and Related Equipment
other than in connection with Collocation Services.  Tenant's Agents agree to be
accompanied at all times by Landlord's designated  representative when access to
the Roof Space or Related Equipment areas is necessary for installation,  repair
and  maintenance;   Landlord  will  make  such  representative   available  upon
reasonable prior notice.  Tenant will make every  reasonable  effort to minimize
the number of service  calls made to the Roof Space or Related  Equipment  areas
and will enter such only for required  maintenance  or in case of an  emergency.
Tenant must secure and maintain at all times all required  approvals and permits
of the  Federal  Communications  Commission  and all other  governmental  bodies
having jurisdiction over its business, including its communications,  operations
and  facilities.  Landlord may require Tenant to cease  operation of or relocate
(at  Tenant's  cost and  expense)  the  Chillers,  Dishes,  Antennae and Related
Equipment  upon notice to Tenant if  Landlord  reasonably  determines  that such
installation  or use materially  interferes  with the operation of machinery and
apparatus of the  Building,  such as the  elevators,  and Tenant fails to remedy
such condition as soon as reasonably  practicable  and not later than 3 business
days. In no event shall Landlord be responsible for any interruption of services
or use of the  Building  caused by the  Chillers,  Dishes,  Antennae and Related
Equipment.  If the machinery or apparatus of the Building is equipment  that was
installed following  completion of the Base Building Work, the costs of any such
relocation shall be


                                       3
<PAGE>

borne by Landlord and the relocation is scheduled and performed in a manner that
minimizes any disruption to Tenant and its use of the Chillers, Dishes, Antennae
and Related  Equipment.  Landlord may suspend or terminate Tenant's right to use
the Roof under this  Section as required  upon  notice to Tenant,  to the extent
that it is found by a public  authority  having  jurisdiction  over the Building
that the  installation  and use of the  Chillers,  Dishes,  Antennae and Related
Equipment  constitute a nuisance or hazard to the public or to the  occupants of
the Building or if this Lease expires or is  terminated  in accordance  with its
terms. If Tenant fails to suspend or terminate  operations as so required at the
request of Landlord, Landlord will be entitled to injunctive relief and the cost
of obtaining such relief will be paid by the prevailing party.

     B. Upon  expiration or earlier  termination,  Tenant will, at its sole cost
and expense,  remove the Chillers,  Dishes,  Antennae and Related  Equipment and
repair any damage  caused to the Roof  Space and  restore  the Roof Space to the
condition   existing  prior  to  such  installation  to  the  extent  reasonably
practicable. Tenant will keep and maintain the Chiller, Dishes, Antennae and the
Related Equipment in good condition and repair, at its sole expense, in a manner
that does not conflict or  interfere  with the use of other  Building  equipment
installed  in the  Building  or on the Roof as of the  Delivery  Date.  Further,
Tenant  will  not  damage  or  permit  damage  to the  Roof or the  Building  in
conjunction with the Chillers, Dishes, Antennae and Related Equipment.

     C. All transmitters  must be equipped with any transmitter  isolator device
as may be required by law or as industry standard for such equipment to minimize
spurious  radiation.  Tenant  shall  indemnify  Landlord for all claims of third
parties with respect to  interference  from  operation of the Chillers,  Dishes,
Antennae and Related  Equipment.  Landlord makes no warranty that the Roof Space
is suitable for the Chillers,  Dishes, Antennae and Related Equipment or that it
will perform according to Tenant's requirements.

     D. Landlord and its agents, employees, contractors or anyone else permitted
by Landlord to be on the Roof may from time to time repair,  replace,  maintain,
or install  additional  improvements or fixtures on the Roof,  provided that the
same do not cause interference with the Chillers or to Tenant's Dishes, Antennae
and Related Equipment, and provided further,  however, that anyone other than an
employee of Landlord or the Building manager shall be required to be accompanied
by a representative  of Landlord or the Building manager at all times.  Landlord
shall not  license  the use of roof space to any third  parties  except to other
tenants in the  Worldgate  Complex  and only to such  tenants if the roof of the
building in which they are located is unsuitable  for operation of the equipment
proposed  to  be  used.  Tenant  will  cooperate  in  any  repair,  replacement,
maintenance  and  installation  as reasonably  required by Landlord from time to
time  consistent  with the  foregoing.  Landlord's  right to permit  such  other
licensees to install  other  rooftop  equipment,  shall be subject to Landlord's
undertaking  to use  reasonable  efforts to coordinate  such  installation  with
Tenant and to subject all such permissions,  licenses, easements and the like to
the condition that such other equipment shall not interfere with the Chillers or
Tenant's  Dishes,  Antennae  and  Related  Equipment  and  operations.   If  any
interference is caused by Landlord or any such other tenant, including,  without
limitation,  as a result of any  subsequent  change or addition of  equipment or
improvements by Landlord,  Landlord agrees to use reasonable  efforts to correct
and  eliminate  such  interference  at  Landlord's  cost in a prompt  and timely
manner,  not to exceed a period of 3 business  days after notice  thereof.  Such
efforts  may  include  modification  of the  third  party  tenant  equipment  or
relocation to another area mutually approved by Landlord and Tenant.

     E.  Tenant  will,  at  Tenant's  sole  cost and  expense,  comply  with all
Applicable  Laws,  or the  requirements  of  Landlord's  insurance  underwriters
relating to the installation, maintenance, height, location, use, operation, and
removal of said Dishes and Related Equipment and indemnify  Landlord against any
loss, cost, or expense incurred  resulting from the  installation,  maintenance,
operation,  or removal of said Dishes and Related  Equipment.  Landlord makes no
representation  that Applicable Laws permit the installation or operation of the
Dishes or Related Equipment.

     F. The insurance  required to be carried by Tenant under Section 16.2 shall
provide coverage with respect to the ownership,  operation and use of the Dishes
and the Related  Equipment.  Landlord has no  responsibility  or  liability  for
damage to the Dishes or the Related Equipment.


                                       4
<PAGE>

     4. Landlord is the owner of an adjacent  parcel of land known  generally as
Worldgate  Parcel 12 on which  Landlord is  constructing  an  additional  office
building  ("Plaza  III").  Landlord  agrees to offer to lease space to Tenant in
Plaza III in accordance with the following provisions:

     A.  Prior to  initial  leasing  of the 7th and 8th  floors  in  Plaza  III,
Landlord shall give notice to Tenant (the "Offer  Notice") of Landlord's  desire
to lease such floors to Tenant (the "RFO  Space"),  provided  that,  if Landlord
desires  at such  time to offer a  portion  or all of the 7th and 8th  floors to
another  proposed  tenant in conjunction  with leasing other space in Plaza III,
Landlord  shall have a right to identify  all of the space being  proposed to be
leased as well (the space  being  proposed  outside of the RFO Space 7th and 8th
floors is referred to collectively as the "Additional Space"); however, Landlord
shall not include  Additional  Space unless the square footage  available on the
7th and 8th floors is not adequate to accommodate the proposed  leasing.  Tenant
has 10 calendar days after  receipt of  Landlord's  Offer Notice within which to
notify  Landlord  if it  elects  to  exercise  its  Right of Offer as to (i) the
entirety  of the RFO Space  floors  included  in such  proposal  (if there is no
Additional  Space  identified  in the Offer Notice) or (ii) the RFO Space floors
included in such proposal and the Additional Space (if there is Additional Space
identified in the Offer Notice).  If there is Additional  Space set forth in the
Offer Notice and Tenant elects to lease the Additional Space,  Tenant shall have
a right to also take the balance of the 7th and 8th floors then available  which
is not  included  in Offer  Notice.  For  example,  if Landlord  identifies  the
Additional  Space as both the 5th and 6th floors and the RFO Space as 1/2 of the
7th floor,  Tenant  shall have the right to elect to  exercise as to (1) the 5th
and 6th floors and all of the 7th,  or (2) the 5th and 6th floors and all of the
7th and all of the 8th floor (assuming the 8th floor is then available).  To the
extent that the  Additional  Space  includes  portions or all of the 5th and 6th
floors in Plaza III, Tenant's right under this Paragraph shall be subject to the
pre-existing rights of Onepoint  Communications  Corp. as tenant under its lease
for space in Plaza I. The space Tenant elects to lease,  in accordance  with the
foregoing  provisions,  as set forth in Tenant's  responsive  notice  ("Tenant's
Election Notice") shall be deemed the "Offer Space."

     B. If Tenant  does not  timely  notify  Landlord,  it will be  conclusively
presumed  that  Tenant has waived its Right of Offer as to the floors of the RFO
Space  included  in the  Offer  Notice,  Landlord  shall  be free to  lease  the
described  RFO Space to anyone  whom it desires  and Tenant will have no further
rights  to the  respective  floors of RFO Space  included  in the Offer  Notice,
provided,  however,  that if after Tenant  waives its right as to any such space
Landlord  desires to lease the space to a prospective  tenant on materially more
beneficial  terms than  provided in  Landlord's  Offer  Notice,  Landlord  shall
re-offer such space on such changed  terms to Tenant  before  leasing to a third
party.  If the Offer  Notice  did not  include  both  floors  of the RFO  Space,
Tenant's  rights as to the excluded floor shall continue in accordance  with the
terms of this  Paragraph  4. For  purposes of this  Addendum:  "more  beneficial
terms"  means an  effective  per square foot rental rate  (taking  into  account
amortization  of  allowances  and rent credits on a straight line basis over the
applicable  term)  which is less  than the rate set  forth in  Landlord's  Offer
Notice;  "materially  more  beneficial  terms"  means an  effective  rental rate
(taking into account  amortization  of allowances and rent credits on a straight
line  basis  over the  applicable  term)  which is 90% or less than the rate set
forth in Landlord's Offer Notice.

     C. The Offer  Notice  shall  include  the lease  term,  the per square foot
rental  rate,  per square  foot  finish  allowance,  terms and  conditions  that
Landlord desires offer to lease the respective space to third parties (including
finish allowance and lease provisions), but in no event shall the rental rate be
less  than the per  square  foot  rental  rate that  Tenant  is  paying  for the
Premises. Except as set forth in Landlord's Offer Notice, the provisions of this
Lease shall be  applicable to such space and, at  Landlord's  option,  evidenced
either in a  separate  lease or, if  mutually  agreed by  Landlord  and  Tenant,
amendment to this Lease;  however,  the provisions of this Addendum shall not be
applicable  to such space and  provisions  regarding  services,  calculation  of
Operating  Expenses  (except  exclusions  of Operating  Expenses  not  otherwise
logically  inapplicable)  and  other  provisions  applicable  to  such  separate
building shall be subject to separate  determination and calculation  consistent
with other leases of space in Plaza III.  Except any finish  allowance  and work
letter  provisions  referred to in the Offer Notice,  all costs of preparing the
space for Tenant's occupancy, including costs of compliance with Applicable Laws
(except  for  compliance  that is the  obligation  of  Landlord  under such work
letter), will be paid by Tenant.


                                       5
<PAGE>

     D. Tenant's  rights under this Paragraph 2 are  conditioned  on: (i) Tenant
not being in default under the Lease at the time it delivers  Tenant's  Election
Notice or on the date that Tenant's  occupancy of the Offered Space is scheduled
to commence;  (ii) Tenant not having  vacated or subleased  more than 25% of the
Premises  or  assigned  its  interest in the Lease  (except as  permitted  under
Section 14.7 of the Lease) at the time it exercises the Right of Offer or on the
date that Tenant's occupancy of the Offered Space is scheduled to commence;  and
(iii) there being at least 2 years  remaining in the Term.  Notwithstanding  the
foregoing,  if there are less than two years  remaining in the Term but Tenant's
rights under this paragraph would otherwise be available to Tenant and an option
to extend the Term is  available  to Tenant  hereunder,  Tenant may exercise its
rights under this Paragraph  provided that Tenant  simultaneously  exercises its
option to extend the term of the Lease. Tenant's rights under this paragraph are
personal to Tenant and may not be assigned  (except as permitted  under  Section
14.7 of the  Lease) and upon an  assignment  of the Lease  (except as  permitted
under Section 14.7), this Paragraph is null and void.

     5.  Tenant,  at  Tenant's  sole cost and  expense,  shall have the right to
install an emergency generator  ("Generator"),  generator fuel tank ("Generat or
Fuel Tank") and  uninterrupted  battery  power source (the "UPS"),  as generally
described  on  EXHIBIT  5 to the  Work  Letter,  ("collectively  the  Generator,
Generator Fuel Tank and UPS are referred to as the "Backup  System") and related
equipment connecting such Backup System to the Premises, including the equipment
referred  to under the  heading  "Riser  Backup  Power" on EXHIBIT 5 to the Work
Letter (the "Backup Related Equipment"). The Generator,  Generator Fuel Tank and
the UPS shall be located in the areas of the Building  Complex labeled "(3)" for
the Generator and Generator Fuel Tank and "(2)" for the UPS on the parking level
one plan  attached as part of EXHIBIT I, with the exact  location and space used
being  designated  by Landlord,  as  reasonably  approved by Tenant.  The Backup
System  and  Backup  Related   Equipment  shall  be  subject  to  the  following
provisions:

     A. The specifications  and types of Generator,  Generator Fuel Tank and UPS
and Backup Related Equipment,  and any alterations thereto,  shall be subject to
the prior  approval  of  Landlord,  which  approval  shall  not be  unreasonably
withheld.

     B. Upon  expiration or earlier  termination,  Tenant will, at its sole cost
and  expense,  remove  and retain  the  Backup  System  and the  Backup  Related
Equipment  and return  the  Building  to the  condition  existing  prior to such
installation.  Tenant will keep and  maintain  the Backup  System and the Backup
Related Equipment in good condition and repair, at its sole expense, in a manner
that does not conflict or interfere with the use of other  facilities  installed
in the  Building.  Further,  Tenant  will not  damage  or  permit  damage to the
Building in conjunction with the Backup System and the Backup Related Equipment.
The  Backup  System and Backup  Related  Equipment  will be of types that do not
cause  interference  with other  equipment  or  operations  in the  Building  or
surrounding  areas to the extent such  interference is unacceptable to Landlord,
in Landlord's reasonable determination.

     C.  Tenant  will,  at  Tenant's  sole  cost and  expense,  comply  with all
applicable laws, rules, regulations,  statutes, ordinances or other requirements
of any kind or  nature  of any  municipal,  state and  federal  governmental  or
quasi-governmental   authority  or  the  requirements  of  Landlord's  insurance
underwriters relating to the installation,  maintenance,  height, location, use,
operation,  and removal of the Backup  System and Backup  Related  Equipment and
indemnify  Landlord against any loss,  cost, or expense incurred  resulting from
the installation,  maintenance,  operation,  or removal of the Backup System and
Backup Related Equipment. Landlord makes no representation that applicable laws,
ordinances or  regulations  permit the  installation  or operation of the Backup
System or Backup  Related  Equipment.  The  insurance  required to be carried by
Tenant under Section 16.2 shall provide  coverage with respect to the ownership,
operation  and use of the  Backup  System  and  the  Backup  Related  Equipment.
Landlord has no  responsibility  or liability for damage to the Backup System or
the Backup Related Equipment.

     6. This Lease is conditioned, at Landlord's option, on Landlord obtaining a
guaranty of the performance of Tenant's obligations and covenants hereunder from
Guarantor,  Bridge Information Systems,  Inc., a Missouri  corporation,  in form
acceptable to Landlord (the  "Guaranty"),  which is subject to  substitution  in
accordance with Section 9.


                                       6
<PAGE>

     IN WITNESS WHEREOF, the parties hereto execute this Addendum.

SAVVIS COMMUNICATIONS  CORPORATION,         WGP  ASSOCIATES,  LLC,  a  Virginia
a Missouri corporation                      limited liability company


                                            By:/s/ Greg Pohle
                                               -----------------
By:/s/ David J. Frear                       Authorized Signatory
   -----------------------                  "Landlord"
Print Name: David J. Frear
           ---------------
Print Title: Executive Vice President
            -------------------------
             Chief Financial Officer

ATTEST:

By:/s/ Steven M. Gallant
   ---------------------
Print Name: Steven M. Gallant
            -----------------
Print Title: Vice President
            -----------------
                  "Tenant"



                                        7
<PAGE>

                               EXHIBIT A TO LEASE

                                  THE PREMISES


<PAGE>

                             EXHIBIT A-1 TO LEASE

                              BUILDING AND PLAZA I


<PAGE>

                               EXHIBIT B TO LEASE

                                  REAL PROPERTY

Parcel 28-A as shown on the plat entitled "Plat of Subdivision and Dedication of
Various  Easements  through  the  property  of  Worldgate   Associates   Limited
Partnership"  attached to that certain Deed of Subdivision and Easement,  by and
between Worldgate Associates Limited Partnership and The Town of Herndon,  dated
August 27, 1998 and recorded  September  29, 1998 in Deed Book 10587,  page 129,
among the Land Records of Fairfax County, Virginia.


<PAGE>

EXHIBIT C TO LEASE

                               OPERATING EXPENSES

     6.1 Definitions.  The additional terms below have the following meanings in
this Lease:

     (1)  "Base  Operating  Expenses"  means an  amount  equal to the  Operating
Expenses for the calendar  year  identified  as the Base Year in Section 1.5, as
determined  by Landlord in accordance  with this Exhibit C. Tenant  acknowledges
Landlord has not made any  representations or warranties that the Base Operating
Expenses will equal any specified  amounts (any  estimates  provided by Landlord
are non-binding estimates only).

     (2)  "Landlord's  Accountants"  means that  individual  or firm employed by
Landlord  from  time to time to keep the  books  and  records  for the  Building
Complex, and/or to prepare the federal and state income tax returns for Landlord
with respect to the Building Complex, which books and records shall be certified
to by a representative of Landlord.  All determinations  made hereunder shall be
made by Landlord's Accountants unless otherwise stated.

     (3) "Rentable Area" means 80,582 rentable square feet of space. If there is
a significant  change in the aggregate Rentable Area as a result of an addition,
partial  destruction,  modification to building  design,  or similar cause which
causes a reduction or increase in the Rentable Area on a permanent  basis or, if
Landlord  remeasures  the  Building  and  a  change  in  Rentable  Area  occurs,
Landlord's  Accountants  shall make such  adjustments in the computations as are
necessary to provide for such change.

     (4)  "Tenant's  Pro Rata Share" means the  percentage  set forth in Section
1.5. If Tenant,  at any time  during the Term,  leases  additional  space in the
Building or if the Rentable  Area is adjusted,  Tenant's Pro Rata Share shall be
recomputed by dividing the total rentable square footage of space then leased by
Tenant  (including any additional  space) by the Rentable Area and the resulting
figure shall become Tenant's Pro Rata Share.

     (5)  "Operating  Expense  Year" means each  calendar  year during the Term,
except that the first Operating Expense Year begins on the Commencement Date and
ends on December 31 of such year and the last  Operating  Expense Year begins on
January 1 of the calendar year in which this Lease expires or is terminated  and
ends on the date of such expiration or termination. If an Operating Expense Year
is less than  twelve  (12)  months,  Operating  Expenses  for such year shall be
prorated.

     (6) "Operating Expenses" means all operating expenses of any kind or nature
which  are  in  Landlord's  reasonable  judgment  necessary,   appropriate,   or
customarily  incurred in connection  with the operation and  maintenance  of the
Building Complex. Operating Expenses include:

     (a) All real property taxes and assessments levied against the Building and
a proportionate share of amounts levied against the rest of the Building Complex
by any  governmental  or  quasi-governmental  authority or under any  covenants,
declarations,   easements  or  restrictions,   including   taxes,   assessments,
surcharges,  or service or other fees of a nature not  presently in effect which
are hereafter levied on the Building  Complex as a result of the use,  ownership
or operation of the Building Complex or for any other reason, whether in lieu of
or in addition to, any current real estate taxes and assessments.  However,  any
taxes which are levied on the rent of the Building Complex will be determined as
if the Building Complex were Landlord's only real property. In no event do taxes
and assessments  include any federal or state income taxes levied or assessed on
Landlord.  Expenses for tax consultants to contest taxes or assessments are also
included as Operating  Expenses (all of the foregoing are collectively  referred
to herein as "Taxes").  Taxes also include special  assessments,  license taxes,
business license fees, business license taxes,  commercial rental taxes, levies,
charges,  penalties or taxes,  imposed by any  authority  against the  Premises,
Building  Complex  or any  legal or  equitable  interest  of  Landlord.  Special
assessments are deemed payable in such number of installments  permitted by law,
whether or not actually so paid,  and include any applicable  interest,  but not
penalties or penalty interest on such installments. Taxes


                                       1
<PAGE>

(other than special  assessments)  are computed on an accrual basis based on the
year in  which  they are  levied,  even  though  not paid  until  the  following
Operating  Expense Year.  Notwithstanding  the foregoing or anything else to the
contrary, The terms "taxes", "assessments",  "special assessments," "Real Estate
Taxes"  "real   property   taxes"  or  "Taxes"   shall  exclude  (and  under  no
circumstances shall Real Estate Taxes or Taxes include) profit taxes,  franchise
taxes,  inheritance  taxes, gift taxes,  transfer taxes,  excise taxes,  capital
levies or similar taxes on Landlord's  business or any assessments to the extent
no substantial  benefit  accrues to Tenant.  In addition,  if the Building,  the
parking  facilities  or the  Property  are  subject  to any  provision  for  tax
abatement  during  the Base  Year as a result  of the  incomplete  status of the
Building Complex, the Base Operating Expenses for determining  increases in Real
Estate  Taxes shall be adjusted to reflect the  estimated  taxes that would have
been  applicable  for  a  fully  completed  Building  Complex.   If  substantial
additional  improvements  are added to the Plaza I Building or if there occurs a
rehabilitation  of or improvement  to the Plaza I Building,  Tenant shall not be
responsible  for increases in Real Estate Taxes  attributable to such additional
improvements  or  rehabilitation.  In the event any tax contest is  pending,  in
progress  or  contemplated  in respect of the Real Estate  Taxes,  the base Real
Estate  Taxes  for  determining  Tenant's  share  shall  not  be  reduced  as  a
consequence  of such contest until a final  determination.  In the event any tax
contest  subsequent  to the year on which base Real Estate Taxes are  determined
shall  result in a  reduction  of Real  Estate  Taxes,  Operating  Expenses  and
Tenant's Pro Rata Share of  Operating  Expenses  for the  applicable  Lease Year
shall be readjusted  upon a final  determination.  Landlord shall be entitled to
deduct  from the amount of the  readjustment  the actual out of pocket bona fide
expenses  incurred  by  Landlord  in  securing  such  reduction  so long as such
expenses are  appropriately  allocated to the  respective  years as to which the
reduction applies;

     (b) Costs of supplies,  including costs of relamping and replacing ballasts
in all Building standard tenant lighting;

     (c) Costs of energy for the Building  Complex,  including costs of propane,
butane, natural gas, steam, electricity, solar energy and fuel oils, coal or any
other energy sources;

     (d) Costs of water and sanitary and storm drainage services;

     (e) Costs of janitorial and security services;

     (f) Costs of general maintenance, repairs, and replacements including costs
under  HVAC  and  other  mechanical  maintenance  contracts;   and  repairs  and
replacements  of equipment used in  maintenance  and repair work;

     (g) Costs of maintenance, repair and replacement of landscaping;

     (h)  Insurance  premiums for the Building  Complex,  including  all-risk or
multi-peril  coverage,  together with loss of rent endorsement;  the part of any
claim  paid under the  deductible  portion of any  insurance  policy  carried by
Landlord;  public  liability  insurance;  and any  other  insurance  carried  by
Landlord on any component parts of the Building Complex;

     (i) All  labor  costs,  including  wages,  costs of  worker's  compensation
insurance, payroll taxes, fringe benefits, including pension, profit-sharing and
health, and legal fees and other costs incurred in resolving any labor dispute;

     (j) Professional  building  management fees, costs and expenses,  including
costs of office space and storage space required by management  for  performance
of its services;

     (k) Legal,  accounting,  inspection,  and other  consulting fees (including
fees for consultants  for services  designed to produce a reduction in Operating
Expenses  or  improve  the  operation,  maintenance  or state of  repair  of the
Building Complex);


                                       2
<PAGE>

     (l) Costs of capital  improvements and structural  repairs and replacements
to the Building Complex to conform to changes subsequent to the date of issuance
of the  shell  and  core  certificate  of  occupancy  for  the  Building  in any
Applicable Laws (herein "Required Capital  Improvements");  and the costs of any
capital improvements and structural repairs and replacements  designed primarily
to reduce Operating Expenses (herein "Cost Savings Improvements").  Expenditures
for  Required  Capital  Improvements  and  Cost  Savings  Improvements  will  be
amortized  at a market  rate of interest  over the useful  life of such  capital
improvement (as determined by Landlord's  Accountants);  however,  the amortized
amount  of any  Cost  Savings  Improvement  in any  year  will be  equal  to the
estimated resulting reduction in Operating Expenses; and

     (m)  Costs  incurred  for  Landlord's  Accountants  including  costs of any
experts and consultants engaged to assist in making the computations;

"Operating Expenses" do not include:

     (i)  Costs of work,  including  painting  and  decorating,  which  Landlord
performs  for any tenant  other than work of a kind and scope which  Landlord is
obligated  to furnish to all tenants  whose leases  contain a rental  adjustment
provision similar to this one;

     (ii)  Costs  of  repairs,   renovation   or  rebuilding   necessitated   by
condemnation or the exercise of eminent domain or other work occasioned by fire,
windstorm  or  other  insured  casualty  to the  extent  of  insurance  proceeds
received;

     (iii) Any and all of Landlord's costs to lease space in the Building to all
prior,  existing,  and  prospective  tenants,  including,   without  limitation:
consulting  and  marketing  fees,  leasing  commissions,  advertising  expenses,
brokerage   commissions,   legal  fees,   vacancy  costs,  rent  or  other  rent
concessions,   and/or  refurbishment  or  improvement  expenses;  and  costs  of
preparing,  improving or altering any space in preparation  for occupancy of any
new or renewal tenant; rent for management or leasing offices;

     (iv) Costs for any structural maintenance constituting Capital Improvements
or  replacement  or redesign of the  structure  (except  for  Permitted  Capital
Improvements),  including, without limitation, any financing related fees, costs
and expenses,  depreciation  or amortization of costs required to be capitalized
in  accordance  with  generally   accepted   accounting   principles   ("Capital
Improvements")  (other than Permitted  Capital  Improvements),  and professional
fees and  disbursements  incurred  in  connection  therewith;  rentals and other
expenses incurred in leasing systems,  elevators,  or other equipment ordinarily
considered to be of a capital nature,  and costs incurred to achieve  compliance
with any governmental laws, ordinances, rules, regulations or orders (other than
Permitted Capital Improvements);

     (v) Any and all of  Landlord's  payment of  principal or interest due under
any mortgage or deed of trust, payments pursuant to ground leases, declarations,
easements,  license  agreements,  and payments  pursuant to any other agreements
that do not constitute  operating expenses under generally  accepted  accounting
principles,  or for any costs or  expenses  relating to  Landlord's  obligations
under any work letter to construct Tenant improvements;

     (vi) Any and all of  Landlord's  costs to  compel  full  performance  under
leases  with all  prior,  existing  and  prospective  tenants  at the  Building,
including,  without  limitation,  all legal fees, costs, and expenses to collect
rent arrears and recover possession;

     (vii) Compensation  (exclusive of the professional building management fee)
paid to officers of Landlord or officers of the management  agent or anyone else
above the level of Building  manager,  and salaries of Landlord's  employees who
are not engaged in the  day-to-day  management  and  maintenance of the Premises
including,  without limitation,  any compensation paid to clerks,  attendants or
other  persons in  commercial  concessions  operated for profit by Landlord,  or
wages,  salaries or other  compensation  or benefits of other offsite  employees
applicable to the time


                                       3
<PAGE>

spend working at other buildings, other than the Building manager (provided that
with respect to each employee that services the Building and other buildings,  a
pro  rata  share  of such  employee's  salary  shall be  included  in  Operating
Expenses, as applicable);

     (viii) Any costs  incurred to Landlord or an  affiliate of Landlord for the
provision of any goods or  services,  in excess of the cost then  prevailing  in
similar transactions between unrelated parties.

     (ix) Depreciation on the Building Complex, except as specifically set forth
above;

     (x)  Expenses  for  the   correction  of  defects  in  Landlord's   initial
construction  of  the  Building,  Project,  or any  part  thereof,  except  that
conditions (not occasioned by construction defects) resulting from ordinary wear
and tear will not be deemed defects for the purpose of this  category;  the cost
of repair or replacement of any item covered by warranty;

     (xi) The cost of tools, equipment and material used in, and all other costs
associated  with, the initial  construction  of the Building,  the Project,  and
related  facilities;  the cost of any "tap  fees" or one time  lump sum sewer or
water connection fees for the Property;

     (xii) Any  documentary  and transfer  taxes imposed in connection  with the
Lease or any other lease;

     (xiii) Costs arising from the presence of hazardous materials,  substances,
wastes, or asbestos-containing  materials in or about or below the Building, the
Land, or the Project, including without limitation,  hazardous substances in the
groundwater or soil (other than ordinary  maintenance costs,  including changing
filters, etc.), unless the materials,  substances, wastes or asbestos-containing
materials  were in or on the Property due to Tenant's  negligence or intentional
acts;

     (xiv)  Property  management  fees in excess of Five  Percent  (5%) of gross
rentals generated by the Property; and

     (xv)  Interest  on  borrowed   money  or  debt   amortization,   except  as
specifically set forth above.

To the  extent  that  employees,  utilities  or  other  services  or  costs  are
attributable  to the  Building  and  other  buildings  on a common  basis or are
provided for Common Areas, such Operating Expenses shall be reasonably  prorated
by Landlord to reflect costs to be allocated  hereunder to the Building.  If any
lease entered into by Landlord with any tenant in the Building is on a so-called
"net" basis,  or provides for a separate basis of computation  for any Operating
Expenses with respect to its leased premises,  Landlord's Accountants may modify
the  computation  of Base  Operating  Expenses,  Rentable  Area,  and  Operating
Expenses  for a  particular  Operating  Expense  Year to eliminate or modify any
expenses which are paid for in whole or in part by such tenant.  If the Rentable
Area is not  fully  occupied  during  any  particular  Operating  Expense  Year,
Landlord's Accountants may adjust those Operating Expenses which are affected by
occupancy for the particular  Operating  Expense Year to reflect 100% occupancy.
Furthermore,   in  making  any  computations   contemplated  hereby,  Landlord's
Accountants  may  make  such  other  modifications  to the  computations  as are
required in their judgment to achieve the intention of the parties hereto.

     6.2 Additional  Payment.  If any increase occurs in Operating  Expenses for
any  Operating  Expense  Year  during  the Term in excess of the Base  Operating
Expenses,  Tenant  shall pay  Landlord  Tenant's Pro Rata Share of the amount of
such increase (less Estimated  Payments,  if any,  previously made by Tenant for
such year).

     6.3 Estimated  Payments.  During each Operating Expense Year beginning with
the first month of the second  Operating  Expense Year and continuing each month
thereafter  throughout the Term, Tenant shall pay Landlord,  at the same time as
Base Rent is paid,  an amount equal to 1/12 of  Landlord's  estimate of Tenant's
Pro  Rata  Share  of any  projected  increases  in  Operating  Expenses  for the
particular   Operating  Expense  Year  in  excess  of  Base  Operating  Expenses
("Estimated Payment").


                                       4
<PAGE>

     6.4 Annual Adjustments.

     (1) Following the end of each Operating  Expense Year,  including the first
Operating  Expense  Year,  Landlord  shall submit to Tenant a statement  setting
forth the exact  amount of Tenant's Pro Rata Share of the  increase,  if any, of
the Operating  Expenses for the Operating  Expense Year just  completed over the
Base Operating  Expenses.  Beginning with the statement for the second Operating
Expense Year,  each statement shall set forth the  difference,  if any,  between
Tenant's  actual Pro Rata Share of the  increase in  Operating  Expenses for the
Operating  Expense  Year  just  completed  and the  estimated  amount  for  such
Operating  Expense  Year.  Each  statement  shall  also set forth the  projected
increase,  if any, in Operating Expenses for the new Operating Expense Year over
Base Operating  Expenses and the corresponding  increase or decrease in Tenant's
monthly Rent for such new Operating Expense Year above or below the Rent paid by
Tenant for the  immediately  preceding  Operating  Expense Year.  All statements
related to  Operating  Expenses  shall be broken down on a  reasonably  itemized
basis. All books and records pertaining to Operating Expenses and all statements
relating  thereto  shall  conform to generally  accepted  accounting  principles
consistently applied.

     (2) To the extent that Tenant's Pro Rata Share of the increase in Operating
Expenses for the period  covered by a statement is different  from the Estimated
Payment  during the  Operating  Expense  Year just  completed,  Tenant shall pay
Landlord  the  difference  within  30 days  following  receipt  by Tenant of the
statement  or receive a credit  against  the next due Rent,  as the case may be.
Until  Tenant  receives a  statement,  Tenant's  Estimated  Payment  for the new
Operating Expense Year shall continue to be paid at the prior Estimated Payment,
but Tenant shall  commence  payment of Rent based on the new  Estimated  Payment
beginning  on the  first day of the month  following  the month in which  Tenant
receives the statement.  Tenant shall also pay Landlord or deduct from the Rent,
as the case may be, on the date required for the first payment, as adjusted, the
difference,  if any, between the Estimated Payment for the new Operating Expense
Year set forth in the statement and the Estimated  Payment  actually paid during
the new Operating  Expense Year. If, during any Operating Expense Year, there is
a change  in the  information  on which  Tenant  is then  making  its  Estimated
Payments so that the prior estimate is no longer  accurate,  Landlord may revise
the estimate and there shall be such adjustments made in the monthly Rent on the
first day of the month  following  notice  to  Tenant as shall be  necessary  by
either increasing or decreasing,  as the case may be, the amount of monthly Rent
then being paid by Tenant for the balance of the Operating Expense Year.

     6.5  Miscellaneous.  In no event will any decrease in Rent  pursuant to any
provision  hereof  result in a reduction  of Rent below the Base Rent.  Delay by
Landlord in submitting  any  statement  for any Operating  Expense Year does not
affect the  provisions  of this  Section or  constitute  a waiver of  Landlord's
rights for such  Operating  Expense  Year or any  subsequent  Operating  Expense
Years.

     6.6 Dispute.  If Tenant  disputes an adjustment  submitted by Landlord or a
proposed  increase or  decrease  in the  Estimated  Payment,  Tenant  shall give
Landlord  notice of such dispute within 180 days after  Tenant's  receipt of the
adjustment.  If Tenant does not give Landlord  timely notice,  Tenant waives its
right to dispute the particular adjustment. If Tenant timely objects, Tenant may
engage its own certified public accountants  ("Tenant's  Accountants") to verify
the  accuracy  of  the  statement  complained  of or the  reasonableness  of the
estimated increase or decrease.  The person conducting the examination on behalf
of Tenant shall enter into a confidentiality agreement satisfactory to Landlord.
If  Tenant's  Accountants  determine  that an error  has been  made,  Landlord's
Accountants  and Tenant's  Accountants  shall endeavor to agree upon the matter,
failing which such matter shall be submitted to an independent  certified public
accountant  selected by  Landlord,  with  Tenant's  reasonable  approval,  for a
determination which will be conclusive and binding upon Landlord and Tenant. All
costs  incurred by Tenant for Tenant's  Accountants  shall be paid for by Tenant
unless  Tenant's  Accountants  disclose  an error,  acknowledged  by  Landlord's
Accountants   (or  found  to  have  occurred   through  the  above   independent
determination),  of more  than 5% in the  computation  of the  total  amount  of
Operating  Expenses,  in which event  Landlord  shall pay the  reasonable  costs
incurred by Tenant to obtain such audit. Notwith-


                                       5
<PAGE>

standing the pendency of any dispute,  Tenant shall continue to pay Landlord the
amount  of  the  Estimated  Payment  or  adjustment   determined  by  Landlord's
Accountants  until the adjustment has been determined to be incorrect.  If it is
determined  that  any  portion  of the  Operating  Expenses  were  not  properly
chargeable  to  Tenant,  then  Landlord  shall  promptly  credit or  refund  the
appropriate sum to Tenant.


                                       6
<PAGE>

                               EXHIBIT D TO LEASE

                             [Intentionally deleted]


                                       1
<PAGE>

                               EXHIBIT E TO LEASE

                              RULES AND REGULATIONS

     1. No  sign,  placard,  picture,  advertisement,  name or  notice  shall be
installed  or  displayed  on any part of the  outside or inside of the  Building
without the prior written consent of the Landlord. Landlord shall have the right
to remove,  at Tenant's  expense  and  without  notice,  any sign  installed  or
displayed in violation  of this rule.  All approved  signs or lettering on doors
and walls  shall be printed,  painted,  affixed or  inscribed  at the expense of
Tenant  by a person  or vendor  approved  by  Landlord.  In  addition,  Landlord
reserves  the  right to  change  from  time to time the  format  of the signs or
lettering  and  to  require  previously   approved  signs  or  lettering  to  be
appropriately altered.

     2. The coverings for all windows in each tenant's premises shall be lowered
and closed as reasonably required because of the position of the sun, during the
operation of the Building's  air-conditioning  system to heat, cool or ventilate
such Premises. All tenants with premises visible from one of the lobbies, or any
other public portion of the Building, shall furnish and maintain its premises in
a first-class manner,  utilizing furnishings and other decorations  commensurate
in quality and style with the  furnishings  and decor in the public  portions of
the Building. If Landlord objects in writing to any curtains,  blinds, shades or
screens  attached to or hung in or used in connection with any window or door of
the Premises,  Tenant shall immediately discontinue such use. No awning shall be
permitted on any part of the Premises.  Tenant shall not place anything or allow
anything to be placed  against or near any glass  partitions or doors or windows
which may  appear  unsightly,  in the  opinion of  Landlord,  from  outside  the
Premises.

     3.  Tenant  shall not  obstruct  any  sidewalks,  halls,  passages,  exits,
entrances,  elevators,  escalators  or  stairways  of the  Building.  The halls,
passages, exits, entrances, shopping malls, elevators,  escalators and stairways
are not for the general public.

     4. The  directory  of the  Building  will be provided  exclusively  for the
display or the name and location of tenants only and Landlord reserves the right
to exclude any other names therefrom.

     5. Unless  otherwise  approved by Landlord,  all  cleaning  and  janitorial
services for the Building and the Premises shall be provided exclusively through
Landlord.  Tenant  shall not  cause any  unnecessary  labor by  carelessness  or
indifference to the good order and  cleanliness of the Premises.  Landlord shall
not in any way be  responsible  to any  Tenant for any loss to  property  on the
Premises,  however occurring,  or for any damage to any Tenant's property by the
janitor or any other employee or any other person.

     6. No equipment,  materials,  furniture, packages, supplies, merchandise or
other  property  will be  received in the  Building or carried in the  elevators
except during Ordinary  Business Hours or other hours  reasonably  designated by
Landlord and in such elevators as may be reasonably designated by Landlord.  The
persons employed to move  furnishings,  fixtures and equipment in and out of the
Building  shall be subject to  Landlord's  approval  and,  if  required  by law,
properly  licensed.  Landlord  shall have the right to condition  approval  upon
payment  of an  additional  security  deposit  as a  condition  of  approving  a
particular  moving  company.  Tenant  must make  arrangements  in  advance  with
Landlord for moving large  quantities of furniture and equipment  into or out of
the Building.

     7. Tenant shall not place a load upon any floor which  exceeds the load per
square foot which such floor was  designed to carry and which is allowed by law.
Landlord shall have the right to prescribe the weight,  size and position to all
equipment,  materials,  furniture or other  property  brought into the Building.
Heavy  objects  shall stand on such  platforms as  determined  by Landlord to be
necessary to properly  distribute such weight.  Business machines and mechanical
equipment  belonging  to Tenant  which  cause  noise or  vibration  which may be
transmitted  to the structure of the Building or to any space in the Building to
such a degree as to be  objectionable  to Landlord  or to any  tenants  shall be
placed and maintained by Tenant, at Tenant's expense,  on vibration  eliminators
or other devices sufficient to eliminate noise or vibration. The


                                        1
<PAGE>

persons  employed  to remove such  equipment  in or about the  Building  must be
acceptable to Landlord.  Landlord will not be responsible  for loss of or damage
to, any such equipment or other property from any cause,  and all damage done to
the Building by  maintaining or moving such equipment or other property shall be
repaired at the expense of Tenant.

     8.  Landlord  reserves  the  right to  exclude  from the  Building  outside
Ordinary  Business Hours any person unless that person is known to the person or
employee in charge of the Building and has an access device such as a key, entry
card,  combination  code,  pass  or is  properly  identified.  Tenant  shall  be
responsible  for all persons for whom it requests  passes and shall be liable to
Landlord for all acts of such persons. Any person whose presence in the Building
at any time  shall,  in the  judgment of the  Landlord,  be  prejudicial  to the
safety,  character,  reputation and interests of the Building or its Tenants may
be denied  access to the  Building or may be ejected  therefrom,  including  any
person who in the judgment of Landlord is  intoxicated or under the influence of
liquor or drugs or who  shall in any  manner  do any act in  violation  of these
Rules and  Regulations.  In case of public  excitement or other  commotion,  the
Landlord may prevent all access to the Building  during the  continuance  of the
same,  by closing  the doors or  otherwise,  for the safety  and  protection  of
tenants,  the Building,  and property in the Building.  The Landlord may require
any  person  leaving  the  Building  with a package  or other  object to exhibit
authorization  from the Tenant of the premises  from which the package or object
is removed,  but the establishment and enforcement of such requirement shall not
impose any  responsibility  on the  Landlord to protect  any Tenant  against the
removal of property from its premises. The Landlord shall in no way be liable to
any Tenant for damages or loss arising from the admission, exclusion or ejection
of any person to or from Tenant's  Premises or the Building under the provisions
of this rule.

     9. The toilet rooms, toilets, urinals, wash bowls and other apparatus shall
not be used for any purpose other than that for which they were constructed,  no
foreign  substance or any kind whatsoever  shall be thrown into any of them, and
the expense of any breakage,  stoppage or damage resulting from the violation of
this rule shall be borne by the Tenant  who,  or whose  employees  or  invitees,
shall have caused it.

     10.  Tenant  shall  store all its trash and  garbage  within its  Premises.
Tenant shall not place in any trash box or receptacle  any material which cannot
be  disposed  of in the  ordinary  and  customary  manner of trash  and  garbage
disposal.  All  garbage and refuse  disposal  shall be made in  accordance  with
directions issued from time to time by Landlord.

     11.  Smoking  is  prohibited  at all  times in all  areas of the  Building,
including offices, restrooms, corridors,  stairwells, lobbies and elevators. and
may be  prohibited  in all  outside  Common  Areas of the  Building  Complex  or
restricted by Landlord to specific  locations  designated by Landlord as smoking
areas.  Tenant shall not cause or permit any noise (including playing of musical
instruments,  radio  ortelevision) or unusual or objectionable  odors to emanate
from the Premises  which would annoy other tenants or create a public or private
nuisance  and no  cooking  shall  be  done or  permitted  by any  Tenant  on the
Premises,  except by the Tenant of Underwriters'  Laboratory  approved microwave
oven or equipment for brewing coffee,  tea, hot chocolate and similar  beverages
shall be permitted  provided that such  equipment and use is in accordance  with
all  applicable  federal,  state and city  laws,  codes,  ordinances,  rules and
regulations.  Tenants shall not conduct  directly or indirectly any auction upon
their  premises,  or permit any other  person to  conduct  an  auction  upon the
premises.

     12. No  animals,  birds,  or pets of any kind,  excluding  seeing eye dogs,
shall be allowed in a tenant's premises or the Building.

     13.  Tenant  shall  not use in any  space  or in the  public  halls  of the
Building any hand trucks  except those  equipped  with the rubber tires and side
guards or such other material-handling equipment as Landlord may approve. Tenant
shall not bring any other  vehicles of any kind into the  Building  and bicycles
shall be used or stored only in areas designated by Landlord.

     14. Tenant shall not use the name of the Building in connection  with or in
promoting or advertising the business of Tenant except as Tenant's address.


                                        2
<PAGE>

     15. The  requirements  of Tenant will be attended to only upon  appropriate
application to the office of the Building by an authorized individual. Employees
of Landlord  shall not perform any work or do anything  outside of their regular
duties  unless  under  special  instruction  from  Landlord,  and no employee of
Landlord  will admit any  person  (Tenant or  otherwise)  to any office  without
specific instructions from Landlord. All contractors hired by Tenant to complete
alterations  to the  Premises  shall adhere to the  provisions  of the Lease and
these Rules and  Regulations,  as well as such separate rules and regulations as
Landlord may adopt as requirements for contractors.

     16. Tenant shall cooperate fully with the life safety plans of the Building
established and administered by Landlord.  This includes participation by Tenant
and its employees in exit drills, fire inspections, life safety orientations and
other programs relating to fire safety that may be promulgated by the Landlord.

     17.  Landlord may waive any one or more of these Rules and  Regulations for
the benefit of any particular tenant or tenants,  but no such waiver by Landlord
shall be  construed  as a waiver of such Rules and  Regulations  in favor of any
other tenant or tenants, nor prevent Landlord from thereafter enforcing any such
Rules and Regulations against any or all of the tenants of the Building.

     25.  These  Rules and  Regulations  are in  addition  to,  and shall not be
construed  to in any way  modify  or  amend,  in whole or in  part,  the  terms,
covenants,  agreements  and conditions of any lease of premises in the Building.
In the event of a conflict  between  the terms of the Lease and these  rules and
regulations, the Lease shall control.

     26. Tenant shall be responsible  for the observance of all of the foregoing
rules by Tenant's employees, agents, clients, customers, invitees and guests.


                                       3
<PAGE>

                               EXHIBIT F TO LEASE

                            JANITORIAL SPECIFICATIONS

A. DAILY - Monday through Friday, except legal holidays.

     1. Empty waste baskets, clean ashtrays.

     2. Dust accessible areas of desk tops.

     3. Vacuum   carpet  in  elevator   lobbies,   reception   areas  and  other
high-traffic areas.

B. WEEKLY

     1. Dust accessible areas of furniture, convectors and other furnishings.

     2. Vacuum office area carpeting.

C.   MONTHLY

     1. Mop and buff tile floors.

     2. Dust Venetian blinds, window frames and exterior of lighting fixtures.

     3. Spot clean walls.

     4. Clean telephones.

D. QUARTERLY

     1. Clean and refinish tile floors where necessary.

     2. Clean baseboards.

E. SEMI-ANNUALLY

     1. Wash windows.

F.   ANNUALLY

     1. Wash light fixtures and lenses.

     2. Clean Venetian blinds.


                                       1
<PAGE>

NOTE: Cleaners  will not remove  papers or other  materials  from surfaces to be
      cleaned,  dusted or vacuumed.  Trash not in wastebaskets should be clearly
      marked   "TRASH."   Cleaning  of  private   kitchens   and  baths  is  the
      responsibility of the Tenant.


                                       2
<PAGE>

                               EXHIBIT G TO LEASE

                                   HVAC RATES

The  following  charges  shall  be the  only  charges  applicable  to use of the
Building  heating,  ventilation,  air-conditioning  system (HVAC) after Ordinary
Business Hours (other than electricity which is included in electricity  charges
that are separately metered to Tenant):

     After-hours  operation  of fans  only  (excluding  chiller/air-conditioning
     use): $23.50 per hour

     After-hours operation of chiller/air-conditioning: $37.50 per hour

The  foregoing  charges  are  for  use of all or any  portion  of the  Building,
calculated on an hourly basis (without proration for partial hours).


                                       1
<PAGE>

                               EXHIBIT H TO LEASE

                                     PARKING


                                       1
<PAGE>

                               EXHIBIT I TO LEASE

                Generator, Generator Fuel Tank and UPS Locations


                                       1
<PAGE>

                               EXHIBIT J TO LEASE

     SUBORDINATION, NON-DISTURBANCE AND ATTORNMENT AGREEMENT
     THIS  SUBORDINATION,   NON-DISTURBANCE   AND  ATTORNMENT   AGREEMENT  (this
"Agreement")  is made as of the  24th  day of  January,  2000  among  U.S.  BANK
NATIONAL ASSOCIATION, a national banking association ("Lender"), WGP ASSOCIATES,
LLC,  a   Virginia   limited   liability   company   ("Landlord"),   and  Savvis
Communications Corporation, a Missouri corporation ("Tenant").

                                    RECITALS
     A. Lender has made a loan to Landlord (the "Loan"),  upon certain terms and
conditions.

     B. The Loan is secured by, among other  things,  a Deed of Trust,  Security
Agreement,  Financing Statement and Assignment of Leases and Rents (the "Deed of
Trust")  executed by Landlord for the benefit of Lender and recorded in the real
estate records of Fairfax County,  Virginia on April 16, 1999 in Deed Book 10865
at Page 932. The Deed of Trust  created a first lien upon that certain  tract of
real  property  described  on  Exhibit  A  attached  hereto,  together  with the
improvements constructed or to be constructed thereon (the "Property"). The Loan
is  also  secured  by  other  security  agreements,   financing  statements  and
assignments  (the  Deed of Trust and all such  other  security  instruments  are
hereinafter collectively referred to as the "Collateral Documents").

     C. Tenant is the lessee of part of the Property (the  "Demised  Premises"),
under and by virtue of a lease (the "Lease")  between  Landlord and Tenant dated
January 24, 2000.

     D. It is a  condition  to the Lease that  Lender  confirm  certain  matters
relating  to the Loan and  Lender  is  willing  to do so  provided  that  Tenant
subordinates  the Lease and all of Tenant's rights  thereunder to the Collateral
Documents and the liens and security interests created thereby.

                                    AGREEMENT

     NOW,  THEREFORE,  for good and  valuable  consideration,  the  receipt  and
sufficiency of which are hereby acknowledged, Lender, Landlord and Tenant hereby
agree as follows:

     1. SUBORDINATION.  The Lease and all of Tenant's rights thereunder are, and
shall at all times continue to be,  subordinate to the Collateral  Documents and
the liens and security interests created thereby,  regardless of how often or in
what manner the Loan,  together with the liens securing the same, and any of the
Collateral Documents, may be increased, renewed, extended or modified.

     2. NON-DISTURBANCE.  So long as Tenant is not in default in the performance
of any of the terms, covenants or conditions of the Lease on Tenant's part to be
performed,  after the  expiration  of any grace  periods set forth in the Lease,
Tenant's  possession  and  occupancy  of the Demised  Premises  and the Tenant's
rights and privileges under the Lease shall not be diminished or interfered with
by Lender in the exercise of any of Lender's rights under the Deed of Trust.

     3.  ATTORNMENT.  In the event of the foreclosure of the lien of the Deed of
Trust or if the  Demised  Premises  are  conveyed  to  Lender by deed in lieu of
foreclosure,  Tenant  shall  attorn  to Lender  or the  purchaser  upon any such
conveyance or foreclosure  sale and shall recognize  Lender or such purchaser as
the  lessor  under the Lease and  Lender or such  purchaser  shall have the same
rights  and  remedies  under the Lease as  Landlord.  Such  attornment  shall be
effective and self-operative  without the execution of any further instrument on
the part of any of the  parties  hereto.  From and  after  any such  attornment,
Lender  or such  purchaser  shall be bound to  Tenant  under  all of the  terms,
covenants and conditions of the Lease;  provided,  however,  that Lender or such
purchaser shall not be:


                                       1
<PAGE>

     (a)  liable  for any  action or  omission  of any prior  lessor  (including
Landlord)  except for the right of the Tenant to recoup its  damages for a prior
lessor's  default which have been reduced to a final  judgment  against the Rent
owed under the Lease;

     (b)  bound by any rent  which  Tenant  might  have  paid for more  than the
current month to any prior lessor (including Landlord);

     (c) liable for the return or  application of any security  deposits  unless
Landlord delivers such deposits to Lender or such purchaser;

     (d)  bound by any  amendment  or  modification  of the Lease  made  without
Lender's written consent, which consent shall not be unreasonably withheld; or

     (e) subject to any offsets or  deficiencies  which Tenant might be entitled
to assert against any prior lessor (including  Landlord) except for the right to
recoup its damages for a prior Lessor default which have been reduced to a final
judgment against the Rent owed under the Lease.

     4.  NO  DIMINUTION  OF  LANDLORD'S  RIGHTS.  Nothing  contained  herein  is
intended, nor shall it be construed, to abridge or adversely affect any right or
remedy of  Landlord  under the  Lease in the event of  default  by Tenant in the
performance  of any of the  terms,  covenants  or  conditions  of the  lease  on
Tenant's part to be performed.

     5. NOTICES.  If Tenant gives Landlord notice requesting  arbitration of any
alleged  Landlord  default,  it shall  simultaneously  serve a duplicate  of the
notice  on  Lender,  and  Lender  shall  have the right to  participate  in such
arbitration.  Any notice required or permitted to be given hereunder shall be in
writing and will be deemed given (a) upon personal delivery or upon transmission
by  telecopier  or  similar  facsimile  transrnission  device,  (b) on the first
business day after  receipted  delivery to a courier  service  which  guarantees
next-business-day  delivery,  or (c) on the third business day after mailing, by
registered or certified United States mail, postage prepaid,  in any case to the
appropriate party at its address set forth below:

     IF TO LENDER:

     U.S. Bank National Association
     918 Seventeenth Street, 5th Floor
     Denver, Colorado 80202
     Attention: Craig A. Poulter
     Telecopy No.: (303) 585-4198

     WITH A COPY TO:

     Otten, Johnson, Robinson, Neff & Ragonetti, P.C.
     950 Seventeenth Street, Suite 1600
     Denver, Colorado 80202
     Attention: Michael Westover, Esq.
     Telecopy No.: (303)825-6525


                                       2
<PAGE>

     IF TO LANDLORD:

     WGP ASSOCIATES, LLC
     4643 South Ulster Street, Suite 1500
     Denver, Colorado 80237
     Attention: Donald E. Spiegleman
     Telecopy No.: (303)694-0082

     WITH A COPY TO:

     Isaacson, Rosenbaum, Levy & Woods, P.C.
     633 Seventeenth Street Suite 2200
     Denver, Colorado 80202
     Attention: Lawrence J. Donovan, Jr., Esq.
     Telecopy No.: (303) 292-3152

     IF TO TENANT:

     Steven Gallant, Esq.
     Vice President and General Counsel
     Savvis Communications Corporation
     717 Office Parkway
     St. Louis, Mo. 63141
     Telecopy No.: 314 468-7550

     WITH A COPY TO:

     Richard A.  Cohn, Esq.
     Bryan Cave LLP
     700 Thirteenth Street, N.W.
     Washington, DC 20005-3960
     Telecopy No.: 202 508-6200

     Any party may change such party's  address for notices or copies of notices
by giving notice to the other parties in accordance with this Section.

     6. CHOICE OF LAW. The validity and  construction of this Agreement shall be
governed by the laws of the State of Virginia.

     7. ADDITIONAL PROVISIONS.

     (a)  Tenant  shall not be named or joined  as a party or  otherwise  in any
suit, action or proceeding for the foreclosure of the Mortgage or to enforce any
rights under the Mortgage or the obligation secured thereby. Notwithstanding the
foregoing provisions of this paragraph, if Tenant is an indispensable party in a
foreclosure  proceeding  with respect to the Mortgage,  Mortgagee may so name or
join  Tenant if such naming or joinder  may be  accomplished  without in any way
diminishing  or otherwise  affecting  the rights and  privileges  granted to, or
inuring to the benefit of, Tenant under this Agreement or under the Lease;


                                       3
<PAGE>

     (b) The  possession  by Tenant of the Demised  Premises and Tenant's  right
thereto shall not be  disturbed,  affected or impaired by, nor will the Lease or
the term thereof be terminated or otherwise  affected by (i) any suit, action or
proceeding  upon the  Mortgage or the  obligation  secured  thereby,  or for the
foreclosure  of the  Mortgage or any other  documents  held by the holder of the
Mortgage,  or by any  judicial  sale or  execution  or other sale of the Demised
Premises,  or any deed given in lieu of  foreclosure,  or by the exercise of any
other rights given to any holder of the Mortgage or other  documents as a matter
of law,  or (ii) any  default  under  the  Mortgage  or the  obligation  secured
thereby; and

     (c) Neither the  Mortgage  nor any other  security  instrument  executed in
connection  therewith shall cover or be construed as subjecting in any manner to
the lien thereof, any trade fixtures,  signs or other personal property,  at any
time  furnished or installed by or at the expense of Tenant or its subtenants or
licensees on the Demised Premises regardless of the manner or mode of attachment
thereof.

     8.  MODIFICATIONS.  This  Agreement  may not be  modified  orally or in any
manner  other than by an agreement  in writing  signed by the parties  hereto or
their  respective  successors  in interest.  This  Agreement  shall inure to the
benefit of and be binding upon the parties hereto, their successors and assigns,
and any purchaser or  purchasers at  foreclosure  of the Demised  Premises,  and
their respective heirs, personal representatives, successors and assigns.

     IN WITNESS  WHEREOF,  the parties  hereto have caused this  Agreement to be
duly executed as of the day and year first above written.

                       LENDER:

                       U.S. BANK NATIONAL ASSOCIATION,
                       a national banking association

                       By:_______________________________
                       Name:_____________________________
                       Title:____________________________

                       LANDLORD:

                       WGP ASSOCIATES, LLC, a Virginia limited liability company


                       By:_______________________________
                              Authorized Signatory

                       TENANT:

                       Savvis Communications Corporation, a Missouri corporation

                       By:_______________________________
                       Name:_____________________________
                       Title:____________________________


                                       4
<PAGE>

STATE OF COLORADO                           )
CITY AND                                    )
COUNTY OF DENVER                            )

     On  _______________,  ____,  before  me  ______________________________,  a
Notary Public, personally appeared ________________________________,  personally
known to me (or proved to me on the basis of  satisfactory  evidence)  to be the
person(s)  whose  name(s)  is/are   subscribed  to  the  within  instrument  and
acknowledged  to  me  that  he/she/they   executed  the  same  in  his/her/their
authorized  capacity(ies),   and  that  by  his/her/their  signature(s)  on  the
instrument  the  person(s),  or the entity  upon  behalf of which the  person(s)
acted, executed the instrument.

     WITNESS my hand and official seal.

     My commission expires: __________________________

                                                     ___________________________
                                                     Notary Public

STATE OF __________________                 )
                                            )
COUNTY OF ________________                  )

     On  _______________,  ____,  before  me  ______________________________,  a
Notary Public, personally appeared ________________________________,  personally
known to me (or proved to me on the basis of  satisfactory  evidence)  to be the
person(s)  whose  name(s)  is/are   subscribed  to  the  within  instrument  and
acknowledged  to  me  that  he/she/they   executed  the  same  in  his/her/their
authorized  capacity(ies),   and  that  by  his/her/their  signature(s)  on  the
instrument  the  person(s),  or the entity  upon  behalf of which the  person(s)
acted, executed the instrument.

     WITNESS my hand and official seal.

     My commission expires: __________________________

                                                     ___________________________
                                                     Notary Public

STATE OF __________________                 )
                                            )
COUNTY OF ________________                  )

     On  _______________,  ____,  before  me  ______________________________,  a
Notary Public, personally appeared ________________________________,  personally
known to me (or proved to me on the basis of  satisfactory  evidence)  to be the
person(s)  whose  name(s)  is/are   subscribed  to  the  within  instrument  and
acknowledged  to  me  that  he/she/they   executed  the  same  in  his/her/their
authorized  capacity(ies),   and  that  by  his/her/their  signature(s)  on  the
instrument  the  person(s),  or the entity  upon  behalf of which the  person(s)
acted, executed the instrument.

     WITNESS my hand and official seal.

     My commission expires: __________________________

                                                     ___________________________
                                                     Notary Public


                                       5
<PAGE>

                                    EXHIBIT A
                                       TO
                         SUBORDINATION, NON-DISTURBANCE
                            AND ATTORNMENT AGREEMENT
                               (LEGAL DESCRIPTION)

Parcel 28-A as shown on the plat entitled "Plat of Subdivision and Dedication of
Various  Easements  through  the  property  of  Worldgate   Associates   Limited
Partnership"  attached to that certain Deed of Subdivision and Easement,  by and
between Worldgate Associates Limited Partnership and The Town of Herndon,  dated
August 27, 1998 and recorded  September  29, 1998 in Deed Book 10587,  page 129,
among the Land Records of Fairfax County, Virginia


                                       1
<PAGE>

                                   WORK LETTER
                              Tenant Performs Work

                                January 24, 2000

SAVVIS COMMUNICATIONS CORPORATION

RE:   Lease dated as of the 24th of January,  2000 (the "Lease"), by and between
      WGP ASSOCIATES,  LLC, a Virginia limited liability  company,  as Landlord,
      and SAVVIS COMMUNICATIONS CORPORATION, a Missouri corporation, as Tenant

Re:  Tenant:   SAVVIS COMMUNICATIONS CORPORATION, a Missouri corporation,

Premises:      Approximately   80,582  rentable square feet of space on the 5th,
               6th, 7th and 8th floors (the "Premises")

Address:       12851 Worldgate Drive, Herndon, Virginia

Gentlemen:

     Concurrently herewith, you ("Tenant") and the undersigned ("Landlord") have
executed a Lease (the  "Lease")  covering  the Premises  (initially  capitalized
words not  defined  have the same  meaning  set forth in the  Lease).  This Work
Letter sets forth how certain base building  construction (as defined more fully
below,  "Base Building Work") and certain  interior  finish  construction of the
Premises to be leased by Tenant  pursuant  to the Lease (as  defined  more fully
below,  "Tenant's  Finish Work") are to be constructed,  who will be responsible
for the construction of the base building  improvements and tenant improvements,
who will pay for such  construction,  and the time schedule and  coordination of
activities for the completion of such construction.  All provisions of the Lease
shall apply to this  Agreement  except to the extent clearly  inconsistent  with
this Agreement or otherwise inapplicable. This Agreement is a part of the Lease.
In  consideration  of the execution of the Lease,  Landlord and Tenant  mutually
agree as follows:

1.  Base Building Work; Space Planning and Engineering

1.1 Landlord has provided to Tenant the architectural  and engineering  drawings
for the base building  improvements for the Building and the Building Complex to
be completed by Landlord  ("Base  Building  Drawings")(as  further  described on
EXHIBIT 4 to this Work Letter),  as prepared by Davis, Carter & Scott Architects
(such  architectural  firm or its replacement,  if replaced by Landlord prior to
completion of construction,  is referred to as the "Landlord's Architect").  The
work to be completed by Landlord in accordance  with the Base Building  Drawings
as modified is hereinafter  referred to as the "Base Building Work." Landlord is
responsible  for  having  completed  the  Base  Building  Work  in  a  good  and
workmanlike  manner in accordance with Applicable Laws and the  Declaration,  as
further provided in Section 2.4.

1.2 Tenant has  retained  Davis Carter  Scott as Tenant's  architect  ("Tenant's
Architect") and Burr Computer Environments, Inc. as Tenant's engineer on the 6th
floor and Tolk  Engineering  Inc.  or  Shapiro-O'Brien  Associates  as  Tenant's
overall engineer ( collectively,  "Tenant's  Engineers");  Landlord reserves the
right to elect to retain separate engineers ("Landlord's  Engineers") to provide
a separate review on behalf of Landlord of plans prepared by Tenant's  Architect
and Tenant's Engineers (which review shall be at Landlord's cost and expense and
not as a deduction  from the  Allowance  except  that cost of a review,  if any,
required in  connection  with any request of Tenant to modify the Base  Building
Drawings  or  Base  Building   Work).   Tenant  has  provided  to  Landlord  the
Tenant-approved space plans for the Premises (collectively referred to herein as
"Space Plans") prepared by Tenant's Architect, which plans are dated January 17,
2000;  Tenant  shall also have  Tenant's  Engineers  review  the Space  Plans on
Tenant's behalf for conformity to the Base Building Drawing. The


                                       1
<PAGE>

Space  Plans  shall  contain  information  specified  in  EXHIBIT 1 and shall be
sufficiently complete to permit Landlord and Landlord's Engineers to review such
drawings for the purpose of  conforming  the Space Plans with the Base  Building
Drawings  and for the purposes  described in Section 1.3 below.  The Space Plans
shall be prepared  by Tenant's  Architect  at  Tenant's  sole cost and  expense,
subject to Landlord's payment of the Allowance as hereinafter provided.

1.3 Within 5 business days after the Delivery  Date,  Landlord  shall review the
Space Plans and confer with Tenant concerning such review.  Tenant's  Engineers,
and  Landlord's  Engineers,  if  applicable,  shall  advise  Landlord and Tenant
whether the Base Building Work will have to be supplemented or modified in order
to allow  installation  of work shown on the Space  Plans.  If  Landlord or such
engineers  reasonably  determine that the Space Plans (i) are inconsistent  with
the Base Building Drawings; (ii) do not contain all of the information specified
in EXHIBIT 1 or are not sufficiently  complete to permit Landlord to review them
for the purposes set forth therein;  or (iii) indicate space usages inconsistent
with the  Permitted  Use set forth in the Lease,  Landlord  shall notify  Tenant
within such 5 business day period of Landlord's  determination setting forth the
specific reasons therefor, in reasonable detail. Thereafter, Tenant shall revise
the Space  Plans  accordingly  and  resubmit  them to  Landlord  and the  review
procedure  and time  frames  set forth  above  shall be  repeated.  Any delay by
Landlord in  responding  within the  applicable  periods or delays  arising from
errors by  Landlord or its  engineers  in such  review  process  shall be deemed
"Landlord  Delay" to the extent that such delay results in delaying  approval of
the Approved  Space Plans beyond the 15th day  following  receipt by Landlord of
the initial Space Plans; except for such delay, approval of Approved Space Plans
shall not delay the Commencement  Date under Section 2.4 below. When approved by
Landlord and Tenant,  the Space Plans shall be  acknowledged as such by Landlord
and Tenant  signing each sheet  therefor  and such  approved  drawings  shall be
deemed the "Approved Space Plans."

1.4 Tenant has provided Landlord with architectural working drawings prepared by
Tenant's  Architect  (the  "Architectural  Working  Drawings")  and  structural,
plumbing,  fire  protection,  mechanical  controls,  electrical  and life safety
engineering  drawings  prepared  by  Tenant's  Engineers  ("Engineering  Working
Drawings") for the Premises approved by Tenant for review by Landlord, which are
to be substantially in the form provided in EXHIBIT 1. The Architectural Working
Drawings shall be coordinated by Tenant's Architect with the Engineering Working
Drawings  prepared by Tenant's  Engineers  pursuant to Paragraph 1.3 above.  The
Architectural  Working Drawings and the Engineering  Working Drawings shall be a
logical extension of the Approved Space Plans.  Landlord shall have the right to
have a representative of Landlord attend Tenant's weekly construction  meetings.
Tenant shall have responsibility for any problems caused by any inconsistency of
the Architectural Working Drawings and the Engineering Working Drawings with one
another or with the Base Building  Drawings,  conflicts with building codes, and
any conflicts  between such drawings and field  conditions  disclosed to Tenant.
Landlord,  Landlord's Architect and Landlord's Engineers,  as applicable,  shall
review the Architectural  Working Drawings and the Engineering  Working Drawings
within 7 business  days after the Delivery Date and give notice if they discover
any  conflicts  with  the  Base  Building   Drawings  or  field   conditions  or
noncompliance with building codes within such period. If Landlord does not reply
within such period, it shall be presumed that Landlord has no objection thereto,
however,  such approval shall not limit  Landlord's  right to request changes in
the future in the event design errors are discovered  later (which request shall
be made as soon as practicable following such discovery);  however, Tenant shall
be obligated  only to make changes with regard to design  errors  identified  by
Landlord  after such 7 business  day period that affect the safety of the Finish
Work or that are required by  Applicable  Laws. If Landlord  notifies  Tenant of
such errors  (within the time period,  if  applicable),  Tenant shall revise the
Architectural  Working Drawings and the Engineering Working Drawings accordingly
and resubmit them to Landlord and the review  procedure set forth above shall be
repeated.  Delay caused by such  revisions  shall be deemed Tenant  Delay.  When
approved (or deemed  approved) by Landlord and Tenant,  such  drawings  shall be
deemed the "Final Working Drawings."

1.5  Changes  to the  Final  Working  Drawings,  except  for minor  changes  not
affecting  the Building  mechanical,  electrical  or life safety  systems or the
structure  of the  Building,  may be made only upon prior  written  approval  of
Landlord. Landlord shall respond (in writing or by oral communication thereafter
confirmed in writing) to all written requests for changes within 7 business days
of  Landlord's  receipt of the same.  If Landlord  does not respond  within such
period,  Landlord  shall be deemed to have  consented to the requested  changes.
Tenant shall provide Landlord with revised Final Working Drawings reflecting any
such changes as soon as reasonably  practicable.  Any delay in completion of the
Finish Work or


                                       2
<PAGE>

the Base  Building  Work which  results  from any such changes or the process of
approval or  disapproval  (other than caused by Landlord  Delay) shall be deemed
Tenant  Delay.  Landlord's  review of the  Space  Plans,  Architectural  Working
Drawings, Engineering Working Drawings or Final Working Drawings shall not imply
approval  by  Landlord  for their  completeness,  design  sufficiency,  or as to
compliance with the requirements of applicable  codes,  rules, or regulations of
any governmental agencies having jurisdiction thereof now in effect or which may
hereafter be in effect.

II.  Finish Work and Finish Allowance
2.1 Tenant agrees to execute  contracts for design and construction  services to
complete the Finish Work (the "Contract")  with  contractors and  subcontractors
reasonably  satisfactory  to Landlord  (collectively,  "Tenant's  Contractors").
Tenant and Tenant's  Contractors  will be required to adhere to the requirements
set  forth on  EXHIBIT  2  (collectively,  "Requirements").  The  Contract  will
incorporate  the provisions of the  Requirements or otherwise be consistent with
the  Requirements,  subject to changes as may be approved by Landlord.  Prior to
execution of the Contract, Tenant will provide a copy to Landlord. Landlord will
review the Contract for compliance  with the  Requirements  and advise Tenant of
Landlord's  approval or required changes within 10 business days of receipt;  if
Landlord  fails to  respond  within  such  period,  Landlord  shall be deemed to
approved such contract(s). Following such approval and the Delivery Date, Tenant
will promptly commence and proceed diligently to complete the Finish Work.

2.2 Tenant's Contractors and contractors employed by Landlord who are completing
work in the Building Complex  ("Landlord's  Contractors")  shall be obligated to
mutually cooperate and such Contractors will each conduct its respective work in
an orderly  fashion  and  manner so as not to  unreasonably  interfere  with the
other. Tenant's subcontractors with respect to all mechanical,  electrical,  and
fire protection work in the Premises will be the subcontractors used by Landlord
for  such  work  in  the  Building,  provided,  however,  if  Tenant  bids  such
subcontracts  and the bids of  Landlord's  subcontractors  are in  excess  of 5%
higher  than the next  highest  bid,  Landlord  shall  either  not  unreasonably
withhold  approval  of such  other  subcontractor(s)  or  require  Tenant to use
Landlord's  subcontractor(s)  but pay to Tenant (as  additional  Allowance)  the
difference  between such bids. If requested by Tenant,  Landlord shall supervise
construction  by Tenant's  Contractors,  in which case Tenant shall pay from the
Allowance to Landlord a construction  supervision and management fee equal to 5%
of the total costs of construction of the Finish Work;  otherwise,  Tenant shall
be responsible for supervising Tenant's  Contractors,  but Tenant shall also pay
from the Allowance to Landlord a  construction  coordination  fee equal to 1% of
the total costs of construction of the Finish Work.

2.3 Tenant assumes full responsibility for Tenant's Contractor's  performance of
all  work  including  compliance  with  Applicable  Laws,  and for all  Tenant's
Contractors' property, equipment, materials, tools or machinery placed or stored
in the  Premises  during  the  completion  thereof  (subject  to the  provisions
regarding Builder's Risk insurance).  All such work is to be performed in a good
and workmanlike manner consistent with first class standards.

2.4 Landlord  has notified  Tenant that  Landlord has  determined  that the Base
Building Work has been Substantially Completed.  "Substantially Completed" means
that all of the following have occurred: (i) Landlord has performed or completed
substantially  all of the Base  Building  Work  which is the  responsibility  of
Landlord to complete in accordance with the Base Building Drawings and this Work
Letter,  except only punch list items which: (1) do not substantially  interfere
with Tenant's ability to perform and complete Tenant's Finish Work, otherwise to
complete  improvements to the Premises to be made by Tenant or occupy or use the
Premises,  and (2) which are reasonably  projected to be completed  prior to the
Rent  commencement  dates  provided  in Section 4 of the Lease for the  affected
areas; and (ii) all approvals, certificates of occupancy and permits (other than
Tenant's  business  licenses and  certificates  of occupancy  pertaining  to the
completion of Tenant's  Finish Work),  and those permits and approvals  from the
appropriate  governmental  authorities  pertaining  to the Base Building Work or
other  improvements  to be  constructed  by Landlord  required for the legal and
practical  occupancy  of the Premises  (except for such  permits  which by their
terms cannot be issued until Tenant's  Finish Work is completed);  and (iii) the
Landlord's  Architect  certifies  in writing to Tenant that the  portions of the
Premises   constituting  Base  Building  Work  and  other   improvements  to  be
constructed by Landlord are substantially complete; and (iv) the construction of
Common Areas, including,  without limitation,  lobbies,  corridors,  loading and
parking facilities and the Base Building Systems serving the Building shall have
been substantially completed and so certified by


                                       3
<PAGE>

Landlord's  Architect and approved by the appropriate  governmental  authorities
(to the extent  required);  and (v) Landlord has effected removal of rubbish and
debris  and  Landlord's  (and  its  contractors')   construction  materials  and
equipment  to the  extent  necessary  to  permit  Tenant  access  and use of the
Building and Premises for  commencing  its Tenant  Finish Work in the  Premises.
Following the Delivery  Date and prior to Tenant's  Contractors  commencing  the
Finish Work, the  representatives  of Landlord and Tenant shall jointly  inspect
the  Premises  with  Landlord's  Architect  and  develop a list of items of Base
Building Work that have not been completed (the items set forth on such list are
referred to herein as "Punch List Items"). In the event of a dispute, Landlord's
Architect and Tenant's  Architect shall mutually resolve such dispute and if the
Architects cannot agree upon a resolution,  the Architects shall jointly appoint
an independent  architect whose  determination  shall be binding on the parties.
The date on which Landlord  delivers a fully executed  original of this Lease to
Tenant is referred to as the  "Delivery  Date."  Following  the  Delivery  Date,
Landlord shall complete the Punch List Items with reasonable  diligence and in a
manner so as to minimize delay or interference with the completion of the Finish
Work by Tenant and Tenant shall  commence  completion of the Tenant Finish Work,
while being  responsible for repair of damage caused by Tenant's  Contractors in
the Building or Premises. Following the Delivery Date, Tenant is responsible for
the diligent  completion of all finish work substantially in accordance with the
Working Drawings (the "Finish Work"),  at its sole cost and expense,  subject to
Landlord's payment of the Allowance.  Tenant's use and occupancy of the Premises
following the Delivery  Date, as well as related use of the Building  Complex in
conjunction  with such use, is subject to all of the terms and provisions of the
Lease  (except for Tenant's  obligation  to pay Base Rent and  utilities,  which
shall be governed by the  provisions  of Section 4 and 7 of the Lease;  it being
understood that no Base Rent or utilities  obligations  shall commence until the
Rent  commencement  dates  provided  in Section 4 of the Lease).  Following  the
Delivery Date, to minimize interference or delay in the completion of the Finish
Work and Punch List  Items,  Tenant  will  cause  Tenant's  Contractors  to: (i)
conduct work so as not to  unreasonably  interfere  with any other  construction
occurring in the Building Complex  (including Punch List Items or occurring with
respect to the adjacent  building  known as Worldgate  Plaza I; (ii) comply with
the  Requirements;   and  (iii)  reach  reasonable   agreement  with  Landlord's
Contractors as to the terms and conditions  for hoisting,  systems  interfacing,
and  use of  temporary  utilities.  Landlord  shall  likewise  cause  Landlord's
Contractors  to : (i)  conduct  work so as not to  unreasonably  interfere  with
Tenant's  Contractors  completion of Finish Work;  (ii)  cooperate with Tenant's
Contractor's to permit their compliance with the  Requirements;  and (iii) reach
reasonable  agreement  with Tenant's  Contractors as to the terms and conditions
for hoisting,  systems interfacing,  and use of temporary utilities. There shall
be no charge for Tenant's and Tenant's Contractors access to the Building or for
use of  elevators  or hoists  and  Landlord  shall  permit  Tenant to  operate a
temporary  construction office on a floor of the Premises following the Delivery
Date or in a location  designated by Landlord elsewhere in the Building Complex,
to the extent  space is available  for such  purpose and  operation is permitted
under  applicable  codes  and  will  not  limit  Landlord's  ability  to  obtain
inspection approvals under applicable codes.

2.5 Landlord will pay the cost of the Finish Work as substantially  completed in
accordance  with the Final  Drawings  (including  the cost of preparation of the
Space Plan and Final  Drawings and Landlord's  review  thereof) in the amount of
$2,457,751.00  (the  "Allowance").  Landlord  shall make progress  payments on a
monthly basis as portions of the Finish Work is completed  following  request of
Tenant in accordance with Section 2.6. Finish Work Costs in excess of the Finish
Allowance ("Excess Costs") will be at Tenant's sole cost and expense and will be
paid promptly by Tenant, subject to the provisions of this Work Letter. Upon the
execution hereof,  Landlord shall pay to Tenant $8,058.20 as reimbursement for a
portion of the costs incurred by Tenant for Tenant's Architect's programming and
test fit design work,  which amount shall be in addition to the  Allowance  (the
"Design Allowance").

2.6 The Allowance is to be expended solely for the benefit of Landlord; that is,
the  Allowance   will  be  expended   only  to  pay  for  design,   engineering,
installation,  and construction of the Finish Work which under the Lease becomes
the property of Landlord upon  installation and for cabling and wiring,  but not
for movable furniture,  equipment, and trade fixtures not physically attached to
the  Premises.  Not more  than  $250,000.00  of the  Allowance  shall be paid to
Tenant's  Architect  and  Tenant's  Engineer  for  planning,  architectural  and
engineering costs (in addition to the Design Allowance). Any of Landlord's costs
and expenses payable to Landlord,  required to be paid by Tenant under this Work
Letter  will  also be paid  out of the  Allowance.  Prior to  Tenant  commencing
construction  of the Finish Work,  Tenant shall provide  Landlord with notice of
the total  estimated  cost of all  Finish  Work.  As  design,  engineering,  and
construction work is completed and


                                       4
<PAGE>

Tenant receives  invoices  therefor,  Tenant will submit requests for payment to
Landlord not more frequently than monthly,  along with  appropriate lien waivers
(substantially in the forms attached hereto as EXHIBIT 3) and such other related
documentation  as Landlord  reasonably  requires.  On a monthly basis  following
receipt of such  documentation  (with such payment being made by the 30th of the
month if all required  documentation  is received by Landlord by the 5th of such
month),  Landlord  will pay the  amounts  requested  by  delivery  to  Tenant of
Landlord's  check(s)  payable to Tenant  or, at  Landlord's  option,  payable to
Tenant  and  Tenant's  Contractors  jointly;  provided,  however,  that  if  the
estimated  costs of completing the Finish Work exceeds the  Allowance,  Landlord
shall have the right to disburse the Allowance on a percentage  basis,  equal to
that  percentage  of the  invoiced  work that  equals  the  percentage  that the
Allowance  constitutes of the total estimated  costs of the Finish Work.  Unless
otherwise  agreed by Landlord and Tenant in writing and subject to delays beyond
Tenant's reasonable control, if any portion of the costs to be reimbursed by the
Allowance has not been  requested by Tenant or will be requested for Finish Work
that is ongoing as of December  31, 2000 (which  deadline  shall be extended for
Finish  Work  ongoing  at the  time of such  deadline)  such  amounts  shall  be
forfeited by Tenant.

2.7  Landlord  will,  during  completion  of the  Finish  Work  and  immediately
thereafter,  reasonably  cooperate in the  balancing of the Building HVAC system
serving  the  Premises.  Landlord  shall  pay for  costs of  balancing  the Base
Building Work portions of the HVAC system  (including the central fans discharge
and the perimeter  heating/cooling  zone) and Tenant shall pay for balancing the
portions of the system within the Premises.

2.8  Subject to the  mutual  waiver in Section  18.6 of the Lease,  Tenant  will
indemnify,  defend and hold harmless Landlord,  Building Manager, and Landlord's
Contractors from and against liability, costs or expenses,  including attorney's
fees on account of damage to the person or property  of any third party  arising
out of, or resulting from the performance of the Finish Work, including, but not
limited  to,  mechanics'  or other  liens or claims  (and all  costs  associated
therewith),  subject to  Landlord's  obligation  to disburse  the  Allowance  in
accordance with the foregoing provisions. Tenant will also repair or cause to be
repaired  at its expense all damage  caused to the  Premises or the  Building by
Tenant's  Contractors  or its  subcontractor,  subject to the  mutual  waiver in
Section  18.6 of the Lease  and the  provisions  for  Builder's  Risk  insurance
provided in this Work Letter and Exhibits. Further, Landlord will have the right
as  described  in  Section  12.1 of the Lease to post and  maintain  notices  of
non-liability.  Subject  to the  mutual  waiver in  Section  18.6 of the  Lease,
Landlord  will   indemnify,   defend  and  hold  harmless  Tenant  and  Tenant's
Contractors from and against liability, costs or expenses,  including attorney's
fees on account of damage to the person or property  of any third party  arising
out of, or resulting  from the  performance  of the Base Building Work and other
improvements  and work  performed  by Landlord  and  Landlord's  Contractors  on
Landlord's behalf,  including,  but not limited to, mechanics' or other liens or
claims (and all costs associated therewith).  Landlord will also repair or cause
to be repaired at its expense all damage  caused to the Premises or the Building
by Landlord 's Contractors or its  subcontractors,  subject to the mutual waiver
in Section 18.6 of the Lease and the  provisions  for Builder's  Risk  insurance
provided in this Work Letter and Exhibits.

2.9 Tenant agrees to submit to Landlord  within 60 days following  completion of
all work one  reverse  mylar  sepia  and two  blueprint  copies  of the as built
drawings (the Final Drawings  showing all changes  thereon as marked by Tenant's
Contractors in the field to show field modifications).

2.10  Notwithstanding  any  provision  herein or in the  Lease to the  contrary,
Tenant's Rent obligations and other  obligations will not be delayed or extended
by any delay in completion of the Finish Work;  provided,  however,  that Tenant
shall be entitled to an  abatement  of Base Rent for any portion of the Premises
as to which Tenant's  completion of Finish Work for such portion of the Premises
is delayed by Landlord Delay or by a casualty  occurring after the Delivery Date
that is covered by the Builder's  Risk insurance  carried by Landlord.  The term
"Landlord Delay" means any delay designated as such in this Work Letter or delay
in the  preparation,  finalization  or  approval  of the  Space  Plans,  Working
Drawings or  completion  of the Finish Work caused by  Landlord's  or Landlord's
Contractors'  failure to perform its or their obligations under this Work Letter
within the time limits set forth herein that cause a delay in the  completion of
the Finish Work,  including,  without  limitation,  as a result of  interference
caused by  Landlord  or  Landlord's  Contractors  (to the extent  not  permitted
herein);  Tenant shall provide  notice to Landlord as soon as Tenant  determines
that  Landlord  Delay has  occurred.  All delays other than  Landlord  Delay are
deemed "Tenant Delay."


                                       5
<PAGE>

2.11 Tenant designates and authorizes Dave Simmons,  of the Orr Company,  to act
for  Tenant in this Work  Letter.  Tenant  has the  right by  written  notice to
Landlord to change its designated representative.


                                       6
<PAGE>

2.12 Landlord  designates and authorizes  George Chelwick to act for Landlord in
this Work Letter.  Landlord has the right by written  notice to Tenant to change
its designated representative.

2.13 All  notices  required  hereunder  will be in  writing in  accordance  with
Section 28 of the Lease.  Whenever Tenant's or Landlord's approval or consent is
required  under the express terms of this Work Letter,  such approval or consent
shall not be unreasonably withheld, conditioned or delayed.

2.14 Landlord  shall obtain  Builder's  Risk insurance on the Base Building Work
and, if available in a form  reasonably  acceptable to Landlord and requested by
Tenant,  on the Finish Work on a Builder's  Risk  Completed  Value Form or other
comparable  coverage;  if  such  coverage  on the  Finish  Work is  obtained  by
Landlord,  Tenant  shall  pay  (by  deduction  from  the  Allowance)  the  costs
attributable to coverage for the Finish Work.  Upon request of Tenant,  Landlord
shall confirm  whether such  coverage of the Finish Work is applicable  prior to
Tenant commencing construction of any portion of the Finish Work. Builder's Risk
insurance if applicable to the Finish Work shall include  naming the interest of
Landlord, Landlord's Contractor and subcontractors,  Tenant, Tenant's contractor
and subcontractors,  and Landlord's  mortgage,  as their respective interest may
appear on a Builder's Risk Completed  Value Form or other  comparable  coverage.
Such Builder's Risk coverage shall be in addition to, and not substitution  for,
the insurance (other than Builder's Risk) required under Exhibit 2 to be carried
by Tenant,  Tenant's  Architect,  Engineers and contractors  with respect to the
Finish Work.

                       Very truly yours,

                       WGP ASSOCIATES, LLC, a Virginia limited liability company

                       By:_________________________________
                                Authorized Signatory
                                   "Landlord"

ACCEPTED AND APPROVED this ____ day
of ______________, 2000.

SAVVIS COMMUNICATIONS CORPORATION, a Missouri corporation

By:_______________________________
Print Name:_______________________
Print Title:______________________

ATTEST:

By:_______________________________
Print Name:_______________________
Print Title:______________________
                  "Tenant"

<PAGE>

                        LIST OF EXHIBITS

Exhibit 1         Space Plan and Drawings
                  Requirements

Exhibit 2         Landlord's Requirements of Tenant
                  the Contractors

Exhibit 3         Form of Lien Waivers
Exhibit 4         Base Building Drawings

<PAGE>

                            EXHIBIT 1 TO WORK LETTER

               SPACE PLANS AND ARCHITECTURAL DRAWINGS REQUIREMENTS

I. Space Plans

     Tenant's Space Plans will comply with the following  requirements which are
     intended  to  assist   Tenant  and  Tenant's   Architect  in  defining  all
     information  required  for  Landlord's  review  of  the  space  usages  and
     evaluation of the improvements contemplated thereby.

     1. All Space  Plans will be drawn to 1/8" scale and may be  produced on CAD
     equipment.

     2. Tenant  will  submit one reverse  mylar sepia and two blue prints of all
     Space Plans with notes  describing  the general intent of the usage and the
     improvement requirements.

     3. The Space Plans and notes will include:  (a)  partition  layout and door
     locations;   (b)  depiction  of  electrical  and  communication   equipment
     requirements   other   than  for   normal   office   equipment,   including
     modifications  required to floor or main telephone or electric closets; (c)
     reflected   ceiling   plan  showing   non-standard   lighting  and  ceiling
     construction or constraints which will affect mechanical,  electrical, fire
     protection or life safety  systems;  (d) Tenant's  special  mechanical  and
     plumbing requirements; (e) Tenant's special floor loading requirements; (f)
     Tenant's requirements for floor penetrations,  including but not limited to
     special stairs,  dumbwaiters,  conveyors,  pneumatic systems,  elevators or
     architectural   features;   and  (g)  approximate   information   regarding
     anticipated  structural  and  mechanical,   electrical,   fire  protection,
     controls and life safety system design requirements.

II. Architectural and Engineering Working Drawings

     Tenant's  submission  of  Architectural  Working  Drawings and  Engineering
     Working Drawings  (collectively  the "Working  Drawings") shall include one
     reverse   mylar  and  two   blueprints   of   Architectural   Drawings  and
     Specifications to Landlord and comply with the following requirements which
     are intended to assist Tenant,  Tenant's Architect and Tenant's Engineer in
     defining all information required by Landlord to complete Landlord's review
     of space usages and the quality and extent of the proposed construction and
     its effect upon the Base Building Work.

     The Working Drawings will depict the quality of Finish Work to be performed
     and must provide for a quality level equal to (as reasonably  determined by
     Landlord) or exceeding the requirements of the Base Building Work.

     The  Architectural   Working  Drawings  and  Engineering  Working  Drawings
     colectively  will include but not be limited to: (a)  partition  layout and
     door locations;  (b) electrical outlets,  including the location and usage;
     (c) telephone  outlets,  including  description of system,  size of conduit
     servicing each outlet, power and mechanical requirements for system and any
     requirements affecting base building construction,  including modifications
     required to floor or main  telephone  rooms;  (d)  reflected  ceiling  plan
     showing  standard and  non-standard  lighting,  switching  requirements and
     ceiling   construction  or  constraints   which  will  affect   mechanical,
     electrical,  fire protection or life safety  systems,  and will include all
     necessary specifications and details of items or construction; (e) Tenant's
     occupancy  capacity,  usage  equipment  loads for all spaces,  particularly
     special  usage  rooms,  including  but not  limited  to  conference  rooms,
     lounges,  coffee rooms,  copy rooms,  computer  terminal or keypunch rooms,
     audio-visual rooms and reproduction


                                       1
<PAGE>

     or print rooms which require special heating, ventilating, air conditioning
     or fire  protection  (all  specifications  on usage or  equipment  therein,
     including BTU per hour output of all equipment and  parameters as to extent
     of special work  required);  (f) Tenant's floor loading for all spaces (all
     specifications,  weight,  vibration and  vibration  isolation for each item
     sufficiently  complete for  structural  engineering  design),  particularly
     special  usage  rooms,  including,  but not limited to file rooms,  storage
     rooms,   computer  rooms  and   reproduction  or  print  rooms;  (g)  floor
     penetrations,  including  but not limited to special  stairs,  dumbwaiters,
     conveyors,  pneumatic systems, elevators or architectural features; and (h)
     all structural,  mechanical, electrical, fire protection, controls and life
     safety systems requirements.

     The Working  Drawings will include the following as well:  (1) all millwork
     and equipment  which will be part of the Finish Work and become part of the
     Premises;  (2) a complete finish schedule for all floors, walls,  ceilings,
     including millwork,  door frames,  etc.; (3) keying schedules;  (4) special
     blocking  requirements  as may be required to support  wall or ceiling hung
     furniture or equipment; and (5) all other information necessary to complete
     construction  of the Premises,  including the  architect's  and  engineer's
     stamps if required by the Building Department.


<PAGE>

                            EXHIBIT 2 TO WORK LETTER

                      LANDLORD REQUIREMENTS OF THE CONTRACT

The Contract  will be subject to review and  approval of Landlord in  accordance
with the Work Letter and will fully incorporate the following provisions. In the
event of any conflict  between any provisions of the Contract and the provisions
below, the provisions below will control.

1. The  Contract  will be in writing  and will  cover all  aspects of the Finish
Work. No Finish Work will be performed  except  pursuant to the Contract.  Fully
executed  copies of the Contract  will be  delivered  to  Landlord.  If Landlord
determines that the Contract does not comply with the provisions hereof, it will
immediately be corrected and no work will be commenced in the Premises until the
deficiencies  have been  corrected.  Any  delays in  completion  resulting  from
modifications  (except as  required by  Landlord  Delay) will be Tenant  Delays.
Following  delivery of a copy of the  Contract to Landlord  and its approval (or
deemed approval),  no material modification will be effective unless and until a
copy thereof has been delivered to Landlord for its review.

2. Changes in the Final  Drawings will be made only upon prior written  approval
(or deemed approval) of Landlord (to the extent required under and in accordance
with Section 1.5 of the Work Letter).

3. Scheduling of Finish Work: The Contract will obligate Tenant's  Contractor to
perform  Finish Work in  accordance  with time  schedules  acceptable to Tenant,
Tenant's  Contractor and Landlord  (which approval shall be based on consistency
with Landlord's schedule for completion of the Base Building Work). Any schedule
proposed by Tenant's  Contractor will be based upon Tenant's Contractor applying
its best efforts to the Finish Work.

4. Tenant's  Contractor will not knowingly perform Finish Work inconsistent with
the Final Working Drawings which will result in a lesser quality installation or
provide  inferior  performance  than that established by the base shell and core
drawings and specifications  covering similar work items. Landlord will have the
right at any time during the performance of Finish Work or thereafter to require
replacement and reconstruction at Tenant's Expense of Finish Work not conforming
to the standards and specifications in the Final Drawings.

5.  Tenant and  Tenant's  Contractor  will give all  notices and comply with all
laws, ordinances, rules, regulations and orders of any public authority relating
to the  performance of the Finish Work. If either party observes that any Finish
Work is at variance  with any  applicable  codes,  ordinances,  laws,  rules and
regulations (collectively, "Applicable Laws"), it will promptly notify the other
party and Landlord in writing,  and necessary changes will be made by Tenant. If
Tenant's  Contractor  performs  any  Finish  Work that it knows is  contrary  to
Applicable  Laws,  and fails to deliver  prior  notice to Tenant  and  Landlord,
Tenant's Contractor will assume full  responsibility  therefor and will bear all
costs  attributable  to repair,  replacement  or  correction.  Tenant,  Tenant's
Contractor and its subcontractors will comply with Federal,  State and local tax
laws, social security acts,  unemployment  compensation acts and such other acts
and laws as are applicable to the performance of Finish Work.

6. All risk of loss to all  property  of  Tenant,  Tenant's  Contractor  and its
subcontractors  will be the sole  responsibility of Tenant,  Tenant's Contractor
and its  subcontractors,  and  Landlord  will have no  responsibility  therefor,
subject to Builder's  Risk insurance on the Finish Work to the extent carried by
Landlord in accordance with Section 2.14 of the Work Letter.


                                       1
<PAGE>

7. The following insurance requirements will be complied with:

     a. Minimum  Coverage - Prior to any Finish Work being commenced by Tenant's
     Contractor, it will obtain and maintain insurance with minimum coverage and
     limits to protect  Tenant and Landlord from the claims  hereafter set forth
     which may arise or result from  Tenant's  Contractor's  performance  of any
     Finish Work,  whether such work is  performed by Tenant's  Contractor,  its
     subcontractors,  or by anyone for whose acts such  parties may be liable as
     follows (subject to the provisions below, such limits may be provided by an
     appropriate "umbrella" policy):

          (1) Workmen's  Compensation and occupational  disease insurance at the
          statutory limits provided for by the State of Virginia;

          (2) Employer's liability insurance in an amount not less than $100,000
          for all damages arising from each accident or occupational disease;

          (3) Commercial general liability insurance covering:

               (i) Operations premises liability;

               (ii)Owner's and Contractor's protective liability;

               (iii) Completed operations;

               (iv)Product liability;

               (v) Contractual liability;

               (vi) Broad form property  damage  endorsement and property damage
          caused by conditions  otherwise  subject to exclusion  for  explosion,
          collapse or underground damage;

               (vii) Architect's and engineer's professional liability insurance
          (for Tenant's Architect and Tenant's Engineer)

          (4) Insurance limits:

               Bodily Injury:

               $1,000,000  each  occurrence;   $1,000,000   aggregate  completed
               operations products

               Property Damage

               $500,000 each occurrence; $500,000 aggregate operations; $500,000
               aggregate  protective;  $500,000 aggregate  completed  operations
               products

          (5) Comprehensive  automobile  liability insurance covering all owned,
          hired or  non-owned  vehicles  including  the  loading  and  unloading
          thereof with limits of no less than:

               Automobile Bodily Injury:
               $500,000 each person; $1,000,000 each occurrence;


                                       2
<PAGE>

               Automobile Property Damage:
               $500,000 each person

     b. Unless Landlord  retains  Builder's Risk insurance on the Finish Work in
     accordance with Section 2.14 of the Work Letter, Tenant or Tenant's general
     contractor  shall carry  Builder's  Risk  insurance  covering the completed
     value of the Finish Work which will afford coverage against "all risks" for
     physical loss or damage.

     c.  Cancellation  - All  such  insurance  will be  carried  with a  company
     reasonably  satisfactory  to Landlord and Tenant and the  liability  policy
     will name Landlord and Tenant and their  employees and agents as additional
     insured  parties.  Each policy will provide that it will not be canceled or
     altered  except after 15 days prior written  notice to Tenant and Landlord,
     and the certificate of insurance will so state.

     d. Policy  Termination - Tenant's  Contractor and each  subcontractor  will
     maintain all insurance  required  hereunder during the term of the Contract
     and for a period ending one year after the date of completion of all Finish
     Work done pursuant to the Contract to the extent such  insurance is written
     in a "claims made basis."

     e. Policies - Prior to commencement of work by Tenant's Contractor, it will
     deliver one copy of the policies or certificates  evidencing such insurance
     to Tenant  and  Landlord.  Such  policies  must be  approved  by Tenant and
     Landlord prior to commencement of work. Notwithstanding the above, Landlord
     may  require  greater  coverage  or larger  limits by serving  notice  upon
     Tenant. Without the written consent of Landlord, Tenant's Contractor agrees
     that it will not  allow any  subcontractor  to  commence  work  within  the
     building until such subcontractor has obtained the required insurance.

     f. Umbrella Liability  Insurance - Umbrella liability insurance with limits
     of  liability  for claims of bodily  injury,  personal  injury and property
     damage  liability not less than $10,000,000 each occurrence and $10,000,000
     aggregate.

     g. Waiver of Subrogation - Landlord,  Tenant and Tenant's  Contractor  will
     waive all rights  against  each other,  and their  respective  contractors,
     subcontractors and  sub-subcontractors,  agents and employees,  for damages
     caused by fire or other perils  covered under the Builder's  Risk insurance
     policy on the Finish Work.

9. Tenant's  Contractor  will  indemnify,  defend,  and hold harmless Tenant and
Landlord and their  respective  representatives,  agents and employees  from and
against all claims, damages, losses and expenses,  including, but not limited to
reasonable  attorney's fees, arising out of or resulting from the performance of
Finish Work or Tenant's  Contractor's  failure to perform in accordance with the
Contract  (but  specifically  excluding the Finish Work itself and the Building)
which are:  a) caused in whole or in part by any  negligent  act or  omission of
Tenant's Contractor,  any subcontractor,  anyone directly or indirectly employed
by any of them or anyone for whose acts any of them may be liable, regardless of
whether or not such claim,  loss, damage or expense is caused in part by a party
indemnified hereunder, and b) attributable to bodily injury,  sickness,  disease
or death, or destruction of or damage to tangible property including loss of use
resulting from any of the foregoing acts.


<PAGE>

Tenant's  indemnification  obligation under this Paragraph 9 will not be limited
by any  limitation  on the amount or type of damages,  compensation  or benefits
payable  by  or  for  the  Contractor  or  any  subcontractor   under  workmen's
compensation acts, disability benefit acts or other employee benefit acts.

10.  Tenant's  Contractor  and Tenant  will agree that while  Landlord  may make
available  to  Tenant's  Contractor  for  incorporation  into  the  Finish  Work
materials previously purchased by Landlord,  Landlord is not the manufacturer of
such materials nor is it the commercial supplier of such materials. Accordingly,
Tenant  and  Tenant's  Contractor  will agree that if either one or both of them
have any claim with  respect to any of such  materials  supplied by Landlord for
incorporation  into the Finish Work,  whether such claims  relate to any alleged
breach of an express  warranty or an implied  warranty or otherwise,  any claims
against  Landlord  whether  directly or by way of defense,  counterclaim,  cross
claim or  offset  are  waived  and  released  and such  claims  will be  brought
exclusively  against  the person or entity  from whom  Landlord  purchased  such
materials or against the  manufacturer.  Landlord will execute such documents as
may be reasonably  necessary to assign any rights  Landlord would otherwise have
against a supplier or manufacturer.

11.  Landlord or Tenant may require  Tenant's  Contractor to provide payment and
performance  bonds for any or all  Finish  Work,  such bonds to be  provided  at
Tenant's expense (subject to reimbursement  under the Allowance).  Any bond will
be requested and provided prior to commencement of Finish Work.

12.  If  Tenant's  Contractor  is  adjudicated  a  bankrupt,  or makes a general
assignment  for the benefit of its  creditors,  or if a receiver is appointed on
account  of  Tenant's  Contractor's   insolvency,   or  if  Tenant's  Contractor
persistently  or  repeatedly  refuses or fails,  except in cases  where delay is
justified,  to supply enough properly  skilled workmen or proper materials or if
Tenant's  Contractor  persistently  disregards  Applicable Laws, or otherwise is
guilty of a substantial  violation of a provision of the  Contract,  Tenant may,
without  prejudice to any right or remedy and after giving  Tenant's  Contractor
and its surety, if any, 7 business days' written notice,  terminate the Contract
and take possession of all materials,  equipment,  tools, construction equipment
and machinery  owned by Tenant's  Contractor  and will  thereafter  complete the
Finish Work by whatever  method it may deem  expedient.  In such case,  Tenant's
Contractor will not be entitled to receive any further payments until completion
of all Finish Work;  provided,  however,  that Tenant's actions will not release
Tenant's  Contractor from any obligations to Tenant arising from its performance
or nonperformance prior to the date of such termination.  Following  completion,
Tenant will pay  Tenant's  Contractor  an amount  equal to the  aggregate of the
amounts actually due under the Contract at the time of the termination, less the
cost to Tenant of completing the Finish Work.

13.  Prior  to  commencement  of  any  Finish  Work  in the  Premises,  Tenant's
Contractor will give written notice to Landlord and Tenant of the date work will
commence.  If a subcontractor or materialman files a mechanics' lien as a result
of  performing  Finish Work pursuant to the Contract,  then,  provided  Tenant's
Contractor has been paid for such work,  Tenant's  Contractor will indemnify and
defend Tenant and Landlord from said lien and will,  when requested by Tenant or
Landlord,  furnish (as Landlord or Tenant may specify)  either a bond sufficient
to discharge  the lien,  deposit in an escrow  approved by Landlord and Tenant a
sum  equal  to 150%  of the  amount  of such  lien or  obtain  for  Landlord  an
endorsement  through  Landlord's  title policy  insuring  against loss or damage
resulting from such lien. Subject to any restrictions of Landlord's Mortgagee on
the Building,  Tenant's Contractor may, in cooperation with Landlord and Tenant,
contest the validity of a mechanics' lien,  including the right to prosecute any
appeals so long as during the pendency of any contest,  Tenant's Contractor will
effectively  stay any official or judicial sale of the Building,  upon execution
or  otherwise,  and so long as Tenant's  Contractor  immediately  pays any final
judgment entered and procures record satisfaction thereof. If Tenant or Landlord
is a party to any such contest,  or any other action  resulting  from or arising
out of the  performance  of the Finish Work,  Tenant's  Contractor  will pay all
legal fees and other costs and expenses

<PAGE>

incurred by Landlord and Tenant in such action. If Tenant's  Contractor fails to
provide a bond,  cash escrow or title  endorsement,  or otherwise fails to fully
satisfy  and obtain  the  release of a lien in  accordance  with the  provisions
hereof,  Tenant's Contractor will be obligated to refund Tenant or Landlord,  as
the case may be, all monies that the latter may pay in discharging any such lien
including costs and reasonable  attorneys' fees incurred in settling,  defending
against, appealing or in any other manner dealing with any such lien.

14.  Tenant's  Contractor  will  warrant  and agree at its expense to correct or
cause to be corrected any defects in the Finish Work (including, but not limited
to,  defects  due  to  defective  workmanship  or  materials  whether  supplied,
installed or performed by Tenant's  Contractor or any subcontractor or supplier)
which  occur  within  one  year  after  Tenant's  Contractor  has  substantially
completed the Finish Work,  including  completion of all punchlist items, or for
such  longer  period  as may be  set  forth  in  the  Final  Drawings.  Tenant's
Contractor will require a similar warranty in all subcontracts, and will deliver
to Landlord and Tenant, together with appropriate assignments,  if required, all
warranties of subcontractors  and suppliers.  All warranties will extend to both
Landlord  and Tenant,  as their  respective  interests in such Finish Work exist
pursuant to the Lease.

15. Tenant's  Contractor  will: (a) comply with all reasonable rules relating to
construction  activities in the Building  promulgated  by Landlord or Landlord's
Contractor;  (b) be responsible  for reaching  agreement with Landlord as to the
reasonable  conditions for use of the  elevators,  systems  interfacing,  use of
temporary  utilities,  access to the Premises and use of truck docks and storage
areas (without charge).

16.  Landlord shall make available  hoisting,  systems  interfacing,  and use of
temporary  utilities as is customary in construction of similar buildings in the
suburban Washington, D.C. area, subject to Landlord's schedule for completion of
the Base Building Work.

17.  Landlord  and  Landlord's  Contractor  may,  from time to time,  inspect or
perform work within the Premises. Such inspections or work will not unreasonably
conflict  with  Tenant's   Contractor's  work.  Landlord  may  suspend  Tenant's
Contractor's  work in the Premises if such work,  in the  reasonable  opinion of
Landlord or of  Landlord's  Contractor,  presents a danger to life,  safety,  or
property, or in an emergency situation.

18.  Tenant  will give  Landlord  reasonable  prior  notice of all  inspections,
punchouts and other reviews during the course of  construction  so that Landlord
may observe  such  events.  Landlord  will be likewise  informed of all Building
Department  inspections  and  requirements  for issuance of the  Certificate  of
Occupancy for the Premises.  Landlord's  observation of any such events will, in
no event be construed or  interpreted as a review or approval by Landlord of any
such  work  nor  will  it  prevent  Landlord,  if it  thereafter  discovers  any
deficiency in such Work, from requiring correction.  Tenant's Contractor will be
solely  responsible for obtaining a certificate of occupancy (or its equivalent)
for the  Premises (as  distinguished  from a similar  certificate  to the extent
required  for the Base  Building  Work) and will submit to Landlord the original
prior to  Tenant's  occupancy  of the  Premises  for the  purpose of  conducting
business.

19.  Landlord's  Engineer or other agent will have the option of  reviewing  all
equipment  and materials to be used in the  construction  of the Finish Work for
consistency  with Final Working  Drawings and all work prior to Tenant  move-in.
Such review will in no event constitute  approval by Landlord and Landlord shall
use reasonable efforts to minimize any delay arising from such reviews.

20. Tenant will promptly  furnish  Landlord a copy of the building permit issued
to Tenant's Contractor after issuance.


<PAGE>

21.  Tenant's  Contractor will not store materials or supplies in or outside the
Building (other than within the Premises) without the prior approval of Landlord
or Landlord's Contractor.

22.  All  deliveries  except  hand-held  items  must be taken to the  floors via
elevator(s) designated by Landlord for such purpose.

23. Tenant's Contractor will provide at all times direct supervision of all work
being performed for Tenant.

24.  Tenant's  Contractor  will  cooperate  with  Landlord in  disposing  refuse
resulting from the Finish Work. This may include the use of Landlord's  dumpster
and a proration of charges  associated with such use or at Landlord's  option at
Tenant's  expense the  placement of Tenant  Contractor's  dumpster at a location
reasonably specified by Landlord.

25. Tenant's Contractor will acknowledge that the work to be performed by it for
Tenant is also for the direct benefit of Landlord.  Landlord will have the right
to pursue in its own name directly  against  Tenant's  Contractor  any rights or
remedies including, without limitation, claims for damages granted to Tenant.

If any legal  action or  arbitration  proceeding  is  commenced  to enforce  the
provisions  of the  Contract  or to recover  damages as a result of the  alleged
breach of the  provisions  thereof,  the  prevailing  party will be  entitled to
recover  all  reasonable  costs  incurred  in  connection  therewith,  including
attorneys' fees.

The  Contract  will be  construed  in  accordance  with the laws of the State of
Virginia  Subject to Paragraph 26, any  litigation or other  proceeding  will be
decided by the applicable court in the State of Virginia.

26. All  claims,  disputes  and other  matters in  question  between  Tenant and
Tenant's  Contractor  arising  out of, or  relating  to, the  Contract,  will be
decided by arbitration in accordance with the Construction  Industry Arbitration
Rules of the American Arbitration  Association then obtaining unless the parties
mutually  agree  otherwise.  No such  arbitration  will  include  Landlord,  its
employees or  consultants,  except by written  consent of Landlord and any other
party sought to be joined.


<PAGE>

                            EXHIBIT 3 TO WORK LETTER

                              FORM OF LIEN WAIVERS

Appropriate lien waivers substantially in the forms attached hereto (with blanks
completed and notary revised as appropriate) as Exhibits 3-1, 3-2, 3-3, and 3-4,
as the case may be, will accompany all requests for payment by Tenant.


                                       1

<PAGE>

                           EXHIBIT 3-1 TO WORK LETTER

STATE OF VIRGINIA          )                INTERIM CONTRACTOR'S AFFIDAVIT
                           ) ss.            RELEASE AND LIEN WAIVER
COUNTY OF _____________    )

TO WHOM IT MAY CONCERN:

     The undersigned, being first duly sworn, deposes and says that:

     1.  He is  _______________  of  the  ________________________,  who  is the
general Contractor for the project  hereinafter  identified (the  "Contractor"),
and that the  undersigned  is authorized to execute and deliver this document on
behalf of the Contractor.

     2. The  Contractor is the  contractor  for the  performance of certain work
and/or the furnishing of certain  materials or supplies (the "Work") pursuant to
a Contract between Contractor and _______________________________, as Owner, for
the       improvements       and      project       commonly       known      as
__________________________________________ (the "Project") upon property legally
described    as:    ____________________________________________,    County   of
_______________,  State  of  _______________,  hereinafter  referred  to as  the
"Property."

     3. This  instrument is executed and delivered in  consideration  of and for
the purpose of inducing  _________________________  ("Construction  Lender") and
the Owner to make an interim payment of $__________ under the Contract,  subject
to  collection  of any check given as payment.  The total amount of the Contract
including change orders is $__________,  and the undersigned  acknowledges  that
upon receipt of this  interim  payment,  the  Contractor  has  received  interim
payments totaling $__________ under the Contract.

     4.  The  undersigned  for  the  Contractor,  subject  to  the  receipt  and
collection of the interim  payment  herein  requested,  warrants and  represents
that:  (i) all materials  delivered to said project by or for the Contractor are
for use therein only; (ii) title to all work, materials and equipment covered by
said payment,  whether or not  incorporated  in the improvement on the Property,
has  passed to the  Owner,  free and clear of all  liens,  claims,  security  or
encumbrances   (hereinafter  all  referred  to  as  "liens");  (iii)  all  taxes
applicable  to the  materials  furnished  for use in or on the  Property and all
taxes for the Work  performed  under the Contract have been fully paid; and (iv)
all laborers, mechanics, subcontractors,  materialmen and suppliers for all work
done and for all materials,  machinery,  equipment, fixtures, tools, scaffolding
and appliances  furnished for the  performance of the Contract and for any other
indebtedness  connected  therewith for which the Owner of the Property  might be
responsible have been paid in full to the date hereof. Contractor, to the extent
of the total of interim payments received,  for itself,  its successors,  and on
behalf of all persons able to claim through or under the Contractor: (a) waives,
relinquishes  and  releases all liens and rights of claims to liens for labor or
materials  furnished  in the  construction,  improvement,  alteration  or repair
involved in  performance  under the  Contract;  (b) agrees (1) to save Owner and
Construction Lender harmless from all liability,  costs and expenses,  including
reasonable attorneys' fees, resulting from mechanic's and/or materialmen's liens
for the performance of work or the furnishing of materials or supplies  pursuant
to the  Contract,  (2) to discharge  (by bond or otherwise) or to defend suit to
enforce any mechanic's or  materialmen's  lien,  claim to or right of action for
any such lien which may be filed, and (3) to satisfy any claims or demands which
arise out of, which are due to or which may be made for,  any work  performed or
supplies  furnished under the Contract or in furtherance of the  construction or
completion of the Contract,  whether directly or indirectly  attributable to the
Contract;  and (c) hereby  releases  the  present  and any  future  Owner of the
Property, the Property, the Construction


                                        1
<PAGE>

Lender and any lender who may now or hereafter  have a security  interest in the
Property, from all claims, rights of action,  liabilities and liens which may be
filed or asserted in connection with the Contract.

     Dated this _____ day of _______________, 2000.

                                         _______________________________________
                                         Authorized representative of Contractor

     SUBSCRIBED  AND SWORN TO before  me this  _____ day of  __________________,
2000.

     My commission expires ________________________.

                                         _______________________________________
                                         Notary Public


                                       2
<PAGE>

                           EXHIBIT 3-2 TO WORK LETTER

STATE OF VIRGINIA          )
                           )                FINAL CONTRACTOR'S AFFIDAVIT,
COUNTY OF _____________    )                RELEASE AND LIEN WAIVER

TO WHOM IT MAY CONCERN:

     The undersigned, being first duly sworn, deposes and says that:

     1.  He is  __________________  of  the  _____________________,  who  is the
general Contractor for the project  hereinafter  identified (the  "Contractor"),
and that the  undersigned  is authorized to execute and deliver this document on
behalf of the Contractor.

     2. The  Contractor is the  contractor  for the  performance of certain work
and/or the furnishing of certain  materials or supplies (the "Work") pursuant to
a  Contract  between  Contractor  and  ____________________,  as Owner,  for the
improvements   and   project   commonly   known  as   __________________________
________________________  (the  "Project") upon property  legally  described as:
_________________________________,  County of  __________,  State of __________,
hereinafter referred to as the "Property."

     3. This  instrument is executed and delivered in  consideration  of and for
the purpose of inducing  _________________________  ("Construction  Lender") and
the Owner to make final payment of  $__________  under the Contract,  subject to
collection  of any check  given as  payment.  The total  amount of the  Contract
including change orders is $__________,  and the undersigned  acknowledges  that
upon receipt of this final  payment,  the  Contractor  has been paid in full the
total contract price under the Contract.

     4.  The  undersigned  for  the  Contractor,  subject  to  the  receipt  and
collection of the final payment herein requested,  warrants and represents that:
(i) all materials delivered to said project by or for the Contractor are for use
therein only;  (ii) title to all work,  materials and equipment  covered by said
payment,  whether or not  incorporated in the  improvement on the Property,  has
passed  to  the  Owner,  free  and  clear  of all  liens,  claims,  security  or
encumbrances   (hereinafter  all  referred  to  as  "liens");  (iii)  all  taxes
applicable  to the  materials  furnished  for use in or on the  Property and all
taxes for the Work  performed  under the Contract have been fully paid; and (iv)
all laborers, mechanics, subcontractors,  materialmen and suppliers for all work
done and for all materials,  machinery,  equipment, fixtures, tools, scaffolding
and appliances  furnished for the  performance of the Contract and for any other
indebtedness  connected  therewith for which the Owner of the Property  might be
responsible have been paid in full.  Contractor for itself, its successors,  and
on behalf of all  persons  able to claim  through or under the  Contractor:  (a)
waives,  relinquishes  and  releases all liens and rights of claims to liens for
labor or materials  furnished in the  construction,  improvement,  alteration or
repair involved in performance under the Contract;  (b) agrees (1) to save Owner
and  Construction  Lender  harmless  from all  liability,  costs  and  expenses,
including   reasonable   attorneys'  fees,   resulting  from  mechanic's  and/or
materialmen's  liens for the  performance of work or the furnishing of materials
or supplies pursuant to the Contract, (2) to discharge (by bond or otherwise) or
to defend suit to enforce any  mechanic's  or  materialmen's  lien,  claim to or
right of action  for any such lien which may be filed,  and (3) to  satisfy  any
claims or demands which arise out of, which are due to or which may be made for,
any work performed or supplies furnished under the Contract or in furtherance of
the  construction or completion of the Contract,  whether directly or indirectly
attributable to the Contract; and (c) hereby releases the present and any future
Owner of the Property,  the Property, the Construction Lender and any lender who
may now or hereafter have a security interest in the Property,


                                       1
<PAGE>

from all claims,  rights of action,  liabilities and liens which may be filed or
asserted in connection with the Contract.

     Dated this _____ day of _______________, 2000.


                                         _______________________________________
                                         Authorized representative of Contractor

     SUBSCRIBED  AND SWORN TO before  me this  _____ day of  __________________,
2000.

     My commission expires _______________________.

                                         _______________________________________
                                         Notary Public


                                       3
<PAGE>

                           EXHIBIT 3-3 TO WORK LETTER

                                                      INTERIM
          Project                                     SUBCONTRACTOR'S OR

                                                      MATERIAL SUPPLIER'S
          Job Address                                 AFFIDAVIT,

                                                      RELEASE AND LIEN
          Job Number                                  WAIVER




STATE OF _____________     )
                           ) ss.
COUNTY OF _____________    )

     The undersigned  subcontractor or material  supplier (herein referred to as
"Subcontractor"),  being first duly sworn, deposes and says that: He is over the
age of 21 years and resides at:
_________________________________________________________________.

(IF SUBCONTRACTOR IS AN INDIVIDUAL:)
     1. He is the Subcontractor referred to herein.

(IF SUBCONTRACTOR IS A PARTNERSHIP:)
     1. He is a  general  partner  in  _____________________________________,  a
co-partnership   composed  of  the  undersigned  and  carrying  on  business  at
_______________________________, City of ___________. Said co-partnership is the
Subcontractor referred to herein.

(IF SUBCONTRACTOR IS A CORPORATION:)
     1. He holds the title of  _______________,  in  _______________________,  a
corporation  organized under the laws of the State of ____________,  carrying on
business  at  ________________________________________,  City  of  ____________,
State of _________________,  which corporation is the Subcontractor  referred to
herein. The undersigned is authorized to execute this instrument on its behalf.

     2.   Subcontractor  is  a  subcontractor  or  material   supplier  for  the
performance  of certain  work  and/or the  furnishing  of certain  materials  or
supplies  pursuant  to an  agreement  or  purchase  order,  as the  case  may be
(hereinafter called the "Subcontract," which term will refer to the agreement or
purchase  order,  as  the  case  may  be),  under  a  general  contract  between
_________________________________   (hereinafter   called   "Contractor"),   and
________________________________   (hereinafter  called  the  Owner"),  for  the
improvements   or   project   known   as   ______________________________,    at
_________________________,  City of ____________,  County of ____________, State
of ____________ (hereinafter called the "Property").

     3. This instrument is delivered in  consideration of and for the purpose of
inducing   Contractor  to  make  interim   payment  of  $__________   under  the
Subcontract,  subject to collection of any check given as payment. Subcontractor
acknowledges  that upon  receipt  of this  interim  payment,  Subcontractor  has
received  from  Contractor  interim  payments  totaling  $__________  under  the
Subcontract.


                                       1
<PAGE>

     4. Subcontractor  warrants and represents that: (i) all materials delivered
to said project by or for  Subcontractor are for use therein only; (ii) title to
all work,  material  and  equipment  covered  by said  payment,  whether  or not
incorporated  in the  Property,  has passed to the Owner,  free and clear of all
liens, claims,  security interests or encumbrances  (hereinafter all referred to
as "liens");  (iii) all taxes applicable to the materials furnished and the work
performed  under the  Subcontract  have been fully paid;  and (iv) all laborers,
mechanics,  sub-subcontractors,  materialmen and suppliers for all work done and
for all  materials,  machinery,  equipment,  fixtures,  tools,  scaffolding  and
appliances  furnished for the  performance of the  Subcontract and for any other
indebtedness  connected  therewith for which the Owner of the Property  might be
responsible  have been paid in full to the date  hereof.  Subcontractor,  to the
extent of the total of interim payments  received,  for itself,  its successors,
and on behalf of all persons able to claim through or under  Subcontractor:  (a)
waives,  relinquishes  and  releases  all liens and right or claim to a lien for
labor or materials  furnished in the  construction  improvement,  alteration  or
repair  involved  in  performance  under  the  Subcontract;  (b)  agrees to save
Contractor harmless from all liability, costs and expenses, including reasonable
attorneys'  fees,  to: (1) discharge (by bond or otherwise) or to defend suit to
enforce,  any mechanics' or materialmen's  lien, claim to or right of action for
such lien,  which may be filed and (2) satisfy any claims or demands arising out
of,  due or which  may be  made,  directly  or  indirectly  attributable  to the
Subcontract,  any  work  performed  or  supplies  furnished  thereunder,  or  in
furtherance of the  construction or completion of the subcontract  work; and (c)
hereby  releases  Contractor,  any  money  earned  by  Contractor,  Contractor's
sureties,  the present and any future Owner, the Property and any lender who may
now or hereafter  have a security  interest  therein,  from all claim,  right of
action, liability and lien which may be filed or asserted in connection with the
Subcontract.

     Dated this _____ day of _______________, 2000.

                                         _______________________________________
                                         As Subcontractor, General Partner of
                                         Subcontractor, or Authorized Officer of
                                         Subcontractor, above described

STATE OF _______________   )
                           ) ss.
COUNTY OF _____________    )

     Subscribed and sworn to before me this _____ day of _____________, 2000, by
________________________,  known  to me to be  the  above-named  signatory,  who
personally appeared before me and acknowledged that the foregoing instrument was
freely and  voluntarily  executed for the uses and purposes and on behalf of the
Subcontractor therein mentioned.

     My commission expires ___________________________.


                                         _______________________________________
                                         Notary Public in and for
                                         said County and State


                                       2
<PAGE>

                           EXHIBIT 3-4 TO WORK LETTER

Project

Job Address

Job Number
FINAL SUBCONTRACTOR'S OR

MATERIAL SUPPLIER'S AFFIDAVIT,

RELEASE AND LIEN WAIVER

STATE OF __________        )
                           ) ss.
COUNTY OF _____________    )

     The undersigned  subcontractor or material  supplier (herein referred to as
"Subcontractor"),  being first duly sworn, deposes and says that: He is over the
age of 21 years and resides at:
_______________________________________________________________.

(IF SUBCONTRACTOR IS AN INDIVIDUAL:)
     1.  He is the Subcontractor referred to herein.

(IF SUBCONTRACTOR IS A PARTNERSHIP:)
     1.  He  is  a   general   partner   in   _____________________________,   a
co-partnership   composed  of  the  undersigned  and  carrying  on  business  at
____________________________________________,   City   of   ____________.   Said
co-partnership is the Subcontractor referred to herein.

(IF SUBCONTRACTOR IS A CORPORATION:)
     1.  He  holds  the  title  of  _______________,  in  ______________________
____________________,  a  corporation  organized  under the laws of the State of
____________, carrying on business at _________________________________, City of
____________,  State of  ____________,  which  corporation is the  Subcontractor
referred to herein.  The undersigned is authorized to execute this instrument on
its behalf.

     2.   Subcontractor  is  a  subcontractor  or  material   supplier  for  the
performance  of certain  work  and/or the  furnishing  of certain  materials  or
supplies  pursuant  to an  agreement  or  purchase  order,  as the  case  may be
(hereinafter called the "Subcontract," which term will refer to the agreement or
purchase  order,  as  the  case  may  be),  under  a  general  contract  between
________________________________    (hereinafter   called   "Contractor"),   and
_______________________________________  (hereinafter  called the "Owner"),  for
the   improvements   or   project   known   as    ________________________    at
_____________________________, City of ____________, County of __________, State
of _____________(hereinafter called the "Property").


                                       1
<PAGE>

     3. This instrument is delivered in  consideration of and for the purpose of
inducing Contractor to make final payment of $__________,  subject to collection
of any check given as payment.  Subcontractor  acknowledges that upon receipt of
this final payment,  Subcontractor  has been paid in full the total  subcontract
price of  $__________,  for all of the work  performed  under  the  Subcontract,
including retainage, if any.

     4. Subcontractor  warrants and represents that: (i) all materials delivered
to said project by or for  Subcontractor are for use therein only; (ii) title to
all work,  material  and  equipment  covered  by said  payment,  whether  or not
incorporated  in the  Property,  has passed to the Owner,  free and clear of all
liens, claims,  security interests or encumbrances  (hereinafter all referred to
as "liens");  (iii) all taxes applicable to the materials furnished and the work
performed  under the  Subcontract  have been fully paid;  and (iv) all laborers,
mechanics,  sub-subcontractors,  materialmen and suppliers for all work done and
for all  materials,  machinery,  equipment,  fixtures,  tools,  scaffolding  and
appliances  furnished for the  performance of the  Subcontract and for any other
indebtedness  connected  therewith for which the Owner of the Property  might be
responsible have been paid in full.  Subcontractor  for itself,  its successors,
and on behalf of all persons able to claim through or under  Subcontractor:  (a)
waives,  relinquishes  and  releases  all liens and right or claim to a lien for
labor or materials  furnished in the  construction  improvement,  alteration  or
repair  involved  in  performance  under  the  Subcontract;  (b)  agrees to save
Contractor harmless from all liability, costs and expenses, including reasonable
attorneys'  fees,  to: (1) discharge (by bond or otherwise) or to defend suit to
enforce,  any mechanics' or materialmen's  lien, claim to or right of action for
such lien,  which may be filed and (2) satisfy any claims or demands arising out
of,  due or which  may be  made,  directly  or  indirectly  attributable  to the
Subcontract,  any  work  performed  or  supplies  furnished  thereunder,  or  in
furtherance of the  construction or completion of the subcontract  work; and (c)
hereby  releases  Contractor,  any  money  earned  by  Contractor,  Contractor's
sureties,  the present and any future Owner, the Property and any lender who may
now or hereafter  have a security  interest  therein,  from all claim,  right of
action, liability and lien which may be filed or asserted in connection with the
Subcontract.

     Dated this _____ day of _________________, 2000.

                                         _______________________________________
                                         As Subcontractor, General Partner of
                                         Subcontractor, or Authorized Officer of
                                         Subcontractor, above described

STATE OF _______________   )
                           ) ss.
COUNTY OF _____________    )

     Subscribed and sworn to before me this _____ day of _____________, 2000, by
__________________________,  known to me to be the  above-named  signatory,  who
personally appeared before me and acknowledged that the foregoing instrument was
freely and  voluntarily  executed for the uses and purposes and on behalf of the
Subcontractor therein mentioned.


                                       2
<PAGE>

     My commission expires _______________________.

                                         _______________________________________
                                         Notary Public in and for said
                                         County and State

<PAGE>

                            EXHIBIT 4 TO WORK LETTER

Savvis Project
Base Building Drawings



                                                    SHEET NAME             SHEET NUMBER              LATEST REVISION
---------------------------------------------------------------------------------------------------------------------
                                                                                            
                                                   Cover Sheet                  1 of 11                        05/24
                                                Overview Sheet                  2 of 11                        05/24
                                                Overview Sheet                  3 of 11                        05/24
                                                Landscape Plan                  4 of 11                        05/24
                                                Landscape Plan                  5 of 11                        05/24
                                                Landscape Plan                  6 of 11                        05/24
                                                Landscape Plan                  7 of 11                        05/24
                                                Landscape Plan                  8 of 11                        05/24
                                                Landscape Plan                  9 of 11                        05/24
                                                Landscape Plan                 10 of 11                        05/24
                                             Landscape Details                 11 of 11                        05/24
                                      County Number 6795-SP-17                  1 of 40                        03/24
                         Existing Conditions & Demolition Plan                  2 of 40                        03/24
                                                     Site Plan                  3 of 40                        09/03
                      Sediment & Erosion Control Plan- Phase I                  4 of 40                        07/31
                     Sediment & Erosion Control Plan- Phase II                  5 of 40                        07/31
                   Sediment & Erosion Control- Notes & Details                  6 of 40                        07/31
                                       Sanitary Plan & Profile                  7 of 40                        07/31
                                                      Profiles                  8 of 40                        07/31
                                                      Profiles                 8A of 40                        03/24
                                      Storm Drain Computations                  9 of 40                        07/31
                                                Landscape Plan                 10 of 40                        09/03
                                     Landscape Details & Notes                 11 of 40                        09/03
                                      Fire Lane & Marking Plan                 12 of 43                        09/03
                                          Site Notes & Details                 13 of 40                        03/24
                                          Site Notes & Details                 14 of 40                        07/31
                                           Garage Parking Plan                 15 of 40                        07/31
                                     Geotechnical Requirements                 16 of 40                        03/24

                                   Illustrative Design Drawing                 11 of 13                        06/30
                                        Illustrative Rendering                       12                        06/30
                                        Illustrative Rendering                       13                        06/30
                                              Profiles/Letters                       27                      No Date
                                                      Proffers                       28                      No Date
                                                      Proffers                       29                      No Date
                                     Proffers Per PCA-D-093-11                       30                        11/14
                                                      Proffers                 36 of 40                        07/31
                          Drainage Study- Exisiting Conditions                       31                      No Date
                                     Post Developed Conditions                       32                        04/15
                                            TR-20 Flow Summary                       33                      No Date
                        BMP & Phosphorous Removal Calculations                       34                        08/16
                               Plan & Profile- Worldgate Drive                40A of 40                       Jul-87
                               Plan & Profile- Worldgate Drive                40B of 40                       Jul-87
                                  Project Data & Drawing Index                    A-001                        06/04
                         Door & Partition Types & Door Details                    A-002                        06/04
                                                 Door Schedule                    A-003                        06/04
                                             Hardware Schedule                    A-004                        06/04



                                       1
<PAGE>


                                                                                            
                                               Finish Schedule                    A-005                        06/04
                                        Architechual Site Plan                    A-101                        02/02
                                              Parking- Level 1                    A-201                        06/04
                                              Parking- Level 2                    A-202                        06/04
                                              Parking- Level 3                    A-203                        02/99
                                              Parking- Level 4                    A-204                        02/02
                                       Typical Floor Plan- 1-4                    A-205                        02/02
                            Typical Floor Plan- 1-4  West-East                    A-206                        02/02
                                         Penthouse & Roof Plan                    A-207                        02/02
                                                   Lobby Plans                    A-208                        06/04
                                           Interior Elevations                    A-209                        09/28
                                              Interior Details                    A-210                        06/04
                                    Typical Core & Stair Plans                    A-211                        06/04
                           Toilet Plans - Elevations & Details                    A-212                        02/02
                      Parking Level 4- Ceiling Plan  West-East                    A-213                        06/04
                                           Exterior Elevations                    A-301                        02/02
                                           Exterior Elevations                    A-302                        02/99
                                           Exterior Elevations                    A-303                        02/02
                                    Exterior Elevation/Section                    A-304                        02/02
                                    Exterior Elevation/Section                    A-305                        02/02
                                              Building Section                    A-306                        02/02
                                                 Wall Sections                    A-401                        02/02
                                       Wall Sections & Details                    A-402                        02/02
                                      Exterior Section Details                    A-403                        06/04
                                                  Plan Details                    A-404                        06/04
                                                  Plan Details                    A-405                        06/04
                           Partial Building- Section & Details                    A-501                        06/04
                                       Stair Section & Details                    A-502                        02/02
                       Garage Level P1 - Foundation Plan  West                      S-1                        02/02
                       Garage Level P1 - Foundation Plan  East                      S-2                        02/02
                          Garage Level P2 - Framing Plan  West                      S-3                        02/02
                          Garage Level P2 - Framing Plan  East                      S-4                        02/02
                          Garage Level P3 - Framing Plan  West                      S-5                        02/02
                          Garage Level P3 - Framing Plan  East                      S-6                        02/02
                          Garage Level P4 - Framing Plan  West                      S-7                        02/02
                          Garage Level P4 - Framing Plan  East                      S-8                        02/02
                              Typical Floor Framing Plan  West                      S-9                        02/02
                              Typical Floor Framing Plan  East                     S-10                        02/02
                      Main Roof & Penthouse Framing Plan  West                     S-11                        02/02
                      Main Roof & Penthouse Framing Plan  East                     S-12                        02/02
                                   Penthouse Roof Framing Plan                     S-13                        02/02
                                         Column Schedule  West                     S-14                        02/02
                                         Column Schedule  East                     S-15                        02/02
                                                Beam Schedules                     S-16                        02/02
                                              Structural Notes                     S-17                        02/02
                                               Typical Details                     S-18                        02/02
                                               Typical Details                     S-19                        02/02
                                                      Sections                     S-20                        02/02
                                                      Sections                     S-21                        02/02
                            Cover Sheet  Equip. Sch. & Symbols                      M-1                        02/02
                                              Parking- Level 1                      M-2                        02/02
                               Part Plan Parking- Levels 2 & 3                      M-3                        02/02
                                              Parking- Level 4                      M-4                        02/02



                                       2
<PAGE>


                                                                                            
                                 Typical Floor Plan- 1-3  West                      M-5                        02/02
                                 Typical Floor Plan- 1-3  East                      M-6                        02/02
                                          4th Floor Plan  West                      M-7                        02/02
                                          4th Floor Plan  East                      M-8                        02/02
                              Penthouse Duckwork & Piping Plan                      M-9                        02/02
                                       Typical Floor Core Plan                     M-10                        02/02
                                           4th Floor Core Plan                     M-11                        02/02
                             Riser & Flow Diagrams- Mechanical                     M-12                        02/02
                                           Details- Mechanical                     M-13                        02/02
                                           Details- Mechanical                     M-14                        02/02
                         Schedules, Symbols, & Notes- Plumbing                      P-1                        02/02
                   Parking Level 1- West  Underground Plumbing                      P-2                        02/02
                   Parking Level 1- East  Underground Plumbing                      P-3                        02/02
                   Parking Level 1- West Above Ground Plumbing                      P-4                        02/02
                   Parking Level 1- East Above Ground Plumbing                      P-5                        02/02
                           Parking Level 2 Plan  West Plumbing                      P-6                        02/02
                           Parking Level 2 Plan  East Plumbing                      P-7                        02/02
                           Parking Level 3 Plan  West Plumbing                      P-8                        02/02
                           Parking Level 3 Plan  East Plumbing                      P-9                        02/02
                           Parking Level 4 Plan  West Plumbing                     P-10                        02/02
                           Parking Level 4 Plan  East Plumbing                     P-11                        02/02
                       Typical Floor (1-3) Plan  West Plumbing                     P-12                        02/02
                       Typical Floor (1-3) Plan  East Plumbing                     P-13                        02/02
                                4th Floor Plan-  West Plumbing                     P-14                        02/02
                                4th Floor Plan-  East Plumbing                     P-15                        02/02
                         Penthouse & Roof Plan-  West Plumbing                     P-16                        02/02
                         Penthouse & Roof Plan-  East Plumbing                     P-17                        02/02
                       Typical Core (1-3) Plan-  West Plumbing                     P-18                        02/02
                       Typical Core (1-3) Plan-  East Plumbing                     P-19                        02/02
                                           Water Riser Diagram                     P-20                        02/02
                                        Sanitary Riser Diagram                     P-21                        02/02
                                           Storm Riser Diagram                     P-22                        02/02
                                 Fire Protection Riser Diagram                     P-23                        02/02
                                              Details Plumbing                     P-24                        02/02
               Symbols, Notes, Schedules, & Details Electrical                      E-1                        02/02
                                         Site Plan- Electrical                      E-2                        02/02
                              P1 Garage Level  West Electrical                      E-3                        07/12
                              P1 Garage Level  East Electrical                      E-4                        07/12
                              P2 Garage Level  West Electrical                      E-5                        02/02
                              P2 Garage Level  East Electrical                      E-6                        07/12
                              P3 Garage Level  West Electrical                      E-7                        07/12
                              P3 Garage Level  East Electrical                      E-8                        07/12
                              P4 Garage Level  West Electrical                      E-9                        07/12
                              P4 Garage Level  East Electrical                     E-10                        07/12
                          Typical Floor (1-3)  West Electrical                     E-11                        02/02
                          Typical Floor (1-3)  East Electrical                     E-12                        02/02
                               4th Floor Plan  West Electrical                     E-13                        02/02
                               4th Floor Plan  East Electrical                     E-14                        02/02
                          Penthouse Plan  West/East Electrical                     E-15                        02/02
                       Typical Core Plan  West/East Electrical                     E-16                        02/02
                     Main Lobby Lighting  West/East Electrical                     E-17                        02/02
                               Power Riser Diagram  Electrical                     E-18                        02/02
                             Switchboard Schedules- Electrical                     E-19                        02/02



                                       3
<PAGE>


                                                                                            
                           Fire Alarm Riser Diagram- Elecrical                     E-20                        02/02
                           Fire Alarm Riser Diagram- Elecrical                     E-21                        02/02
                              Panelboard Schedules- Electrical                     E-22                        02/02
                              Panelboard Schedules- Electrical                     E-23                        02/02



                                       4
<PAGE>

                            EXHIBIT 5 TO WORK LETTER

Leasehold Improvements:

Tenant shall have the right to install,  at its sole cost and expenses,  a "7x24
Environmental Infrastructure" plant to support a Data Processing facility within
the space under  lease by Tenant in the  Building.  Such plant shall  include an
emergency  generator,   emergency  generator  fuel  supply,   supplemental  HVAC
equipment,  UPS,  and  associated  risers,  in  accordance  with  the  terms  of
Paragraphs 3 and 5 of the Work Letter.  Such plant design and equipment shall be
identified on Tenant's  Space Plans and reflected in the  Architectural  Working
Drawings and Engineering Working Drawings, as referred to in the Work Letter.

Emergency Generator:
Landlord  shall  provide  space for the  Tenant's  1500 kW to 2000 kW  emergency
generator,  in accordance with Paragraph 5 of the Addendum.  Expenses associated
with the installation,  operation,  and maintenance,  including modifications of
the Base Building Work, shall be borne by the Tenant.

Emergency Generator Fuel Supply:

Landlord  shall provide space for the Tenant's  emergency  generator fuel supply
tank, in accordance  with  Paragraph 5 of the Addendum.  The space shall be used
for  installation  of a 4,000 gallon diesel fuel tank use to supply the Tenant's
generator with fuel. Expenses associated with the installation,  operation,  and
maintenance of the equipment, including modifications of the Base Building Work,
shall be borne by the Tenant.

Supplemental HVAC Equipment:

Tenant  shall be  permitted  to  install  two  chillers,  pumps,  controls,  and
electrical  distribution  equipment  as required to supply the Tenant space with
24x7 redundant  chilled  water.  The chiller shall be located on the roof of the
Building  in  accordance  with  Paragraph  3 of the  Addendum  and  the  related
equipment  shall  be  located  in areas  approved  by  Landlord  and  Tenant  in
accordance  with the Tenant's  Space Plans and  reflected  in the  Architectural
Working Drawings and Engineering  Working  Drawings,  as referred to in the Work
Letter. Expenses associated with the installation, operation, and maintenance of
the equipment,  including any necessary  screening and modifications to the Base
Building Work, shall be borne by the Tenant.

Riser Backup Power:

Landlord  shall provide riser space from the Tenant's  emergency  generator to a
central  distribution  location in the lease space in  accordance  with the Base
Building  Drawings.  The riser space shall be used for  installation  of conduit
containing  control wiring and electrical  distribution cable used to supply the
Tenant space with  emergency  power as reflected  in the  Architectural  Working
Drawings and Engineering  Working  Drawings,  as referred to in the Work Letter.
Expenses  associated with the  installation,  operation,  and maintenance of the
conduit,  including  modifications  of the Base Building Work, shall be borne by
the Tenant.

Riser chilled Water:

Landlord shall provide riser space in accordance with the Base Building Drawings
from the Tenant's  chillers and Related  Equipment  to Tenant's  HVAC  equipment
located in the lease space.  The riser space shall be used for  installation  of
piping used to transport  chilled  water and  requisite  control  wiring used to


                                       1
<PAGE>

supply the Tenant space with such supplemental cooling. Expenses associated with
the installation,  operation,  and maintenance,  including  modifications of the
Base Building Work, shall be borne by the Tenant.

There  will  be  no  additional   rent  for  the  space   utilized  by  Tenant's
Environmental  Infrastructure  plant as  described  herein to the extent such is
located in areas  approved  by  Landlord  within the  Premises,  the  Building's
central plant,  garage, the Building roof, parking lots,  Building property,  or
other mechanical/electrical service areas.


                                       2