TYSONS INTERNATIONAL PLAZA


                             OFFICE LEASE AGREEMENT

                                 by and between

                               485 PROPERTIES, LLC

                                   (Landlord)


                                       and


                       EXCALIBUR TECHNOLOGIES CORPORATION

                                    (Tenant)


                            Date: March 4, 1999



<PAGE>



                           TYSONS INTERNATIONAL PLAZA


                             OFFICE LEASE AGREEMENT


      THIS LEASE AGREEMENT  (this "Lease") is executed in five (5)  counterparts
and  made  as of the  ____  day  of  _____________  1999,  by  and  between  485
PROPERTIES,  LLC,  a  Delaware  limited  liability  company  ("Landlord"),   and
EXCALIBUR TECHNOLOGIES CORPORATION, a Delaware corporation ("Tenant"),  Landlord
and Tenant having the following notice addresses on the date of this Lease:

Landlord:                                       with a copy to:
---------                                       ---------------

485 Properties, LLC
c/o Teachers Insurance and Annuity              LaSalle Partners Limited
  Association of America                        1921 Gallows Road
730 Third Avenue                                Suite 400
New York, New York  10017-3206                  Vienna, Virginia  22182
Attn:  Director, Mortgage and Real Estate       Attn: General Manager

With an additional copy to:
---------------------------

Teachers Insurance and Annuity
    Association of America
730 Third Avenue
New York, New York  10017-3206
Attn: Vice President, Real Estate and Mortgage Law

Tenant:                                   with a copy to:
-------                                   ---------------
Excalibur Technologies Corporation        Werbel & Carnelutti,
1921 Gallows Road, Suite 200                 a Professional Corporation
Vienna, Virginia 22182                    711 Fifth Avenue
Attn:  Ms. Nancy McKinley                 New York, New York 10022
                                          Attn:  Robert H. Werbel, Esquire



                   SUMMARY OF FUNDAMENTAL LEASE PROVISIONS

      The  provisions  set forth below  represent  the  agreement of the parties
hereto  as  to  certain   fundamental  lease  provisions   ("Fundamental   Lease
Provisions").  Specified Section, Schedule and Article references designate some
of the other places in this Lease where additional applicable provisions appear.
The monetary  charges  payable by Tenant set forth in the Summary of Fundamental
Lease  Provisions shall not be construed to constitute an exhaustive list of all
amounts which may become payable under this Lease.



<PAGE>


(a)   Main Term:        Premises Portion #1 ---- Five (5) years   (See ss.3.3)
                        Premises Portion #2 ---- Five (5) years 
                        Premises Portion #3 ---- Five (5) years, five (5)
                                                 months and six (6) days

(b)   Premises Number:  Premises Portion #1 - Suite 200 (Tower II, 2nd Floor)
                                                  (See Sch. A)
                        Premises Portion #2 - Suite 455 (Tower II, 4th Floor)
                        Premises Portion #3 - Suite 750 (Tower II, 7th Floor)

 (c)  Gross Rentable
      Area in Premises: Premises Portion #1 - 11,125 square feet (See ss.1.2)
                        Premises Portion #2 -  3,075 square feet
                        Premises Portion #3 -  4,491 square feet
                                              ------
                              Total           18,691 square feet

(d)   [INTENTIONALLY DELETED]

(e)   [INTENTIONALLY DELETED]

(f)   [INTENTIONALLY DELETED]

(g)   Base Rent:              $28.50 per sq. ft of GRA per .(See ss.4.3, ss.4.4)
                              Lease   Year  (full   service),   with  3%  annual
                              escalations, for an annual Base Rent of:

                              Lease Year  Rental Rate/s.f.
                                    1        $28.50
                                    2        $29.36
                                    3        $30.24
                                    4        $31.14
                                    5        $32.08

(h)   Security Deposit:    $178,000.00 Letter of Credit           (See ss.4.8)

(i)   Permitted Use:       General Office                         (See Art. 5)

(j)   Commencement Date:   Premises Portion #1 - October 6, 1999  (See ss. 4.2)

                           Premises  Portion  #2 - October  6, 1999  Premises
                           Portion #3 - May 1, 1999

<PAGE>


TABLE OF CONTENTS

                                                            Page Number

ARTICLE 1  INTRODUCTORY PROVISIONS...............................1

Section 1.1.  General Definitions................................1
Section 1.2.  Table of Defined Terms.............................2
Section 1.3.  Changes to Project.................................2

ARTICLE 2  PREMISES AND TENANT'S WORK............................3

Section 2.1.  Lease of Premises..................................3
Section 2.2.  Leasehold Improvements and Refurbishments..........3
Section 2.3.  Allowance..........................................4
Section 2.4.  [INTENTIONALLY DELETED]............................5
Section 2.5.  [INTENTIONALLY DELETED]............................5
Section 2.6.  Tenant's Occupancy of Premises.....................5
Section 2.7.  Mechanics' and Other Liens.........................5
Section 2.8.  Tenant's Property................................. 6

ARTICLE 3  TERM................................................. 6

Section 3.1.  Term.............................................. 6
Section 3.2.  Preliminary Term.................................. 7
Section 3.3.  "Main Term," "Lease Year" Defined................. 7
Section 3.4.  Termination....................................... 7
Section 3.5.  Holding Over...................................... 7

ARTICLE 4  RENT................................................. 8

Section 4.1.  Tenant's Agreement to Pay Rent.................... 8
Section 4.2.  Commencement Date..................................8
Section 4.3.  Base Rent..........................................8
Section 4.4.  Annual Rent Increase...............................8
Section 4.5.  Additional Rent....................................9
Section 4.6.  Payment of Rent....................................9
Section 4.7.  Interest Charge....................................9
Section 4.8.  Security Deposit...................................9

ARTICLE 5  USE..................................................10

Section 5.1.  Prompt Occupancy and Use..........................10
Section 5.2.  Operating Hours...................................10
Section 5.3.  Operational Requirements..........................11
Section 5.4.  Signs; Painting; Displays.........................12


<PAGE>

                                TABLE OF CONTENTS

                                                            Page Number
                                                            -----------

ARTICLE 6  TAXES................................................12

Section 6.1.  Real Estate Taxes.................................12
Section 6.2.  Payment of Tenant's Taxes.........................13
Section 6.3.  Taxes on Rent and Other Taxes.....................14

ARTICLE 7  COMMON AREAS.........................................14

Section 7.1.  Use and Management................................14
Section 7.2.  Operating Costs Defined...........................15
Section 7.3.  Tenant's Operating Costs Charge...................17
Section 7.4.  Parking...........................................19
Section 7.5.  Overtime HVAC.....................................19

ARTICLE 8  ENVIRONMENTAL MATTERS................................20

Section 8.1.  Environmental Covenants...........................20
Section 8.2.  Environmental Laws................................20
Section 8.3.  Indemnity.........................................20
Section 8.4.  Pre-existing Conditions...........................20
Section 8.5.  Survival..........................................21

ARTICLE 9  MAINTENANCE, REPAIRS AND ALTERATIONS.................21

Section 9.1.  Landlord's Duty to Maintain Structure.............21
Section 9.2.  Tenant's Duty to Maintain Premises................21
Section 9.3.  Tenant's Duty to Repair Damage....................22
Section 9.4.  Alterations by Tenant.............................22
Section 9.5.  Landlord's Right of Access........................23
Section 9.6.  Disruption in Business Operations.................23

ARTICLE 10  INDEMNITY AND INSURANCE.............................23

Section 10.1.  Tenant's Insurance...............................23
Section 10.2.  Tenant's Contractor's Insurance..................24
Section 10.3.  Policy Requirements..............................24
Section 10.4.  Indemnities by Tenant and Landlord...............25
Section 10.5.  Landlord Not Responsible for Acts of Others......26
Section 10.6.  Landlord's Insurance.............................26
Section 10.7.  Increase in Insurance Premiums...................26
Section 10.8.  Waiver of Right of Recovery......................27

ARTICLE 11  CASUALTY............................................27

Section 11.1.  Obligation to Repair and Reconstruct.............27
Section 11.2.  Option to Terminate Lease........................28
Section 11.3.  Insurance Proceeds...............................28

ARTICLE 12  CONDEMNATION........................................28

Section 12.1.  Effect of Taking.................................28
Section 12.2.  Condemnation Awards..............................29

<PAGE>

ARTICLE 13  ASSIGNMENT AND SUBLETTING...........................29

Section 13.1.  Landlord's Consent Required......................29
Section 13.2.  Transfer; Issuance of Corporate Shares...........30
Section 13.3.  Acceptance of Rent from Transferee...............30
Section 13.4.  Conditions of Consent............................30
Section 13.5.  Profits from Use or Transfer.....................31

ARTICLE 14  DEFAULT.............................................31

Section 14.1.  "Event of Default" Defined.......................31
Section 14.2.  Remedies.........................................32
Section 14.3.  Damages..........................................33

ARTICLE 15  SUBORDINATION, ATTORNMENT
                       AND NON-DISTURBANCE......................35

Section 15.1.  Subordination....................................35
Section 15.2.  Mortgagee's Unilateral Subordination.............35
Section 15.3.  Attornment and Non-disturbance...................36

ARTICLE 16  QUIET ENJOYMENT.....................................36

ARTICLE 17  NOTICES.............................................36

Section 17.1.  Sending of Notices...............................36
Section 17.2.  Notices to Mortgagees............................36
Section 17.3.  Estoppel Certificate.............................37

ARTICLE 18  MISCELLANEOUS.......................................37

Section 18.1.  Modification.....................................37
Section 18.2.  No Recordation...................................37
Section 18.3.  Remedies Cumulative..............................38
Section 18.4.  Successors and Assigns...........................38
Section 18.5.  Compliance with Laws and Regulations.............38
Section 18.6.  Captions and Headings............................39
Section 18.7.    Joint and Several Liability....................39
Section 18.8.    Brokers' Commissions...........................39
Section 18.9.    No Discrimination..............................39
Section 18.10.  No Joint Venture................................40
Section 18.11.  Conflicts; Schedules............................40
Section 18.12.  Severability....................................40
Section 18.13.  No Third Party Beneficiary......................40
Section 18.14.  Corporate Tenants...............................40
Section 18.15.  Applicable Law..................................41
Section 18.16.  Waiver of Jury Trial............................41
Section 18.17.  Limitation of Liability.........................41
Section 18.18.  No Accord and Satisfaction......................42
Section 18.19.  Time of Essence.................................42
Section 18.20.  "Person(s )"Defined.............................42
Section 18.21.  Consents........................................43
Section 18.22.  Integration of all Prior Agreements and 
                    Execution of Lease..........................43

<PAGE>


                                    SCHEDULES


A.....      Drawing showing approximate location of the Premises

A-1...      Legal Description of the Project Site

B.....      Landlord Services

C.....      [INTENTIONALLY DELETED]

D.....      [INTENTIONALLY DELETED]

E.....      Form of Commencement Date Notice

F.....      Rules and Regulations

G.....      Form of Subordination, Non-disturbance and Attornment Agreement

H.....      Form of Tenant Estoppel

I.....      Bids




<PAGE>


                             TABLE OF DEFINED TERMS

                                                               Defined In
Defined Term                                                     Section


ADA ................................................................2.3(e)
Additional Rent ....................................................4.5
Affiliate .........................................................13.1(b)
Allowance ..........................................................2.3 (a)

Base Rent...........................................................4.3
Base Year...........................................................6.1(a)
Building............................................................1.1(a)

Casualty...........................................................11.1
Capital Expenditures................................................7.2(b)(i)
Commencement Date ..................................................4.2
Commencement Date Notice ...........................................2.6
Common Areas........................................................1.1(b)

Default Rate........................................................1.1(c)

Event of Default...................................................14.1
Excess Costs .......................................................2.3 (d)

General Contractor..................................................2.2(b)(i)
GRA.................................................................1.1(d)
GRA Fraction........................................................1.1(e)
GRA Tax Fraction....................................................1.1(f)


Landlord......................................Introductory Paragraph
Landlord's Management Agent.........................................1.1(g)
Lease Year..........................................................3.3(b)
Letter of Credit ...................................................4.8
Liquidated Damages.................................................14.3(a)

Main Term...........................................................3.3(a)
Market Rent.........................................................3.4(d)
Mortgage...........................................................15.1(a)
Mortgagee..........................................................15.1(a)

Operating Costs.....................................................7.2(a)

Parking Garage......................................................7.4(a)
Permitted Use.......................................................5.1


<PAGE>


Person(s)..........................................................18.20
Preliminary Term....................................................3.2
Premises............................................................1.1(h)
Project.............................................................1.1(a)

Rent................................................................4.1
Rental Tax..........................................................6.3

Security Deposit....................................................4.8

Taxes...............................................................6.1(a)
Tenant.........       ..........................Introductory Paragraph
Tenant's Operating Costs Charge.....................................7.3(a)(i)
Tenant's Property...................................................2.8(a)
Tenant's Taxes......................................................6.1(b)
Term................................................................3.1
Termination Damages................................................14.3(a)
Transfer...........................................................13.1(a)
Tysons International Plaza..........................................1.1(a)


<PAGE>


                                    ARTICLE 1

                             INTRODUCTORY PROVISIONS

      Section 1.1.      General Definitions.

      As used herein, the term:

      (a) "Building"  means the referenced  tower of a two-building  multi-story
office and retail project  located in Fairfax  County,  Virginia.  The "Project"
consists of two office/retail  towers and a multi-level  parking facility,  plus
surface parking.  The Project is known as "Tysons  International  Plaza," and is
located at 1919 and 1921 Gallows  Road,  Vienna,  Virginia  22182 (Tower I being
located at 1919 Gallows Road and Tower II being located at 1921 Gallows Road); a
legal  description  of the  Project  site is attached  hereto as  Schedule  A-1.
Landlord  represents  and  warrants  that the estates and  improvements  therein
comprising the Building and the Project are owned by the Landlord in fee simple.
The  Landlord's  fee simple  estate is subject  to a Mortgage  securing  debt to
Teachers Insurance and Annuity Association of America.

      (b)  "Common  Areas"  means  those  areas  and  facilities  which  may  be
furnished, from time to time, by Landlord at the Building, for the non-exclusive
general or limited common use of Landlord, Tenant, other tenants, subtenants and
other occupants of the Project, their officers,  agents,  employees,  customers,
suppliers and materialmen,  and those areas and facilities used for maintenance,
management and marketing of the Project, and all loading docks, ramps and areas,
delivery passages, freight elevators,  service corridors,  sidewalks,  walkways,
roadways,  alleyways,  parking  areas,  courts,  courtyards,  ramps,  fountains,
retaining walls, stairways, escalators, elevators, fire corridors, fire escapes,
park areas,  first-aid  stations,  maintenance and mechanical areas, rest rooms,
meeting  rooms,  management  offices,   promotional  offices,   utility  plants,
distribution equipment,  fire command centers and security systems equipment and
service lines, pipes, tanks, pumps, exhaust fans,  transformers and conduits for
heat,  ventilation,  light  and  air  conditioning,  and  other  similar  areas,
facilities or improvements serving the Project.

      (c) "Default Rate" means an annual rate of interest equal to the lesser of
(i) the maximum rate of interest  for which Tenant may lawfully  contract in the
Commonwealth of Virginia from time to time, or (ii) twenty percent (20%).

      (d) "GRA"  means with  respect to the area being  measured,  the number of
square  feet of  rentable  area for the  exclusive  use by a tenant for  general
office  purposes.  Said area shall be measured in  accordance  with the modified
BOMA method of measurement. From time to time during the Term, Landlord may give
Tenant  notice of the total GRA in the Building and in the Project,  as such GRA
may be revised  because of  additions  to (or  subtractions  from) the  Building
and/or  the Common  Areas  and/or the  Project,  or as such GRA may be  adjusted
pursuant to provisions  in the leases of other tenants or occupants.  The GRA in
the  Premises  and in all other areas set aside for tenants  within the Building
shall  be  utilized  to  calculate  the  GRA  Fraction  and to  make  any  other
calculations  required  to  determine  Tenant's  proportionate  share of certain
charges set forth in this Lease.

<PAGE>

      (e) "GRA Fraction"  means a fraction,  the numerator of which shall be the
GRA in the Premises  and the  denominator  of which shall be the average  annual
aggregate of the total square  footage in the Project which is leased to tenants
from time to time, which  denominator shall in no event be less than that number
which is 95% of the total GRA in the Project.

      (f) "GRA Tax Fraction"  means a fraction,  the numerator of which shall be
the GRA in the Premises and the  denominator  of which shall be the total GRA in
the Project.

      (g) "Landlord's  Management Agent" means the person or persons  designated
by Landlord from time to time to lease,  manage,  operate,  and/or supervise the
operations of the Building for and on behalf of Landlord.

      (h) "Premises"  means that portion of the Building as shown on Schedule A,
having  the  square  footage  of  floor  area  specified  in  clause  (c) of the
Fundamental Lease Provisions. The Premises shall consist of the Premises Portion
#1, the Premises Portion #2 and the Premises Portion #3.

      Section 1.2.      Table of Defined Terms.

      The Section  reference for definitions of all other capitalized terms used
in this Lease are contained in the Table of Defined Terms immediately  following
the Table of Contents.

      Section 1.3.      Changes to Project.

      As between Landlord and Tenant,  Landlord may at any time and from time to
time eliminate or add any improvements,  or change or consent to a change in the
shape,  size,  location,  number,  height or extent of the  improvements  to any
portion of the Building and/or the Project.  Nothing herein contained,  however,
shall be deemed to permit  Landlord to change the  dimensions or location of the
Premises or  materially  adversely  affect the access to the  Premises  from the
Common  Areas  adjacent  thereto,  if any, or  materially  adversely  affect the
appearance or occupancy by Tenant of the  Premises,  without  Tenant's  consent,
unless any such changes are  required by reason of any  federal,  state or local
environmental  or other law, rule,  regulation,  guideline,  judgment,  order or
action.



<PAGE>


                                    ARTICLE 2

                           PREMISES AND TENANT'S WORK

      Section 2.1.      Lease of Premises.

      Landlord,  in consideration of the Rent to be paid and the covenants to be
performed by Tenant, hereby leases to Tenant, and Tenant hereby leases and takes
from Landlord,  for the Term, the Premises, at the rental and upon the covenants
and conditions herein set forth.

      Section 2.2.      Leasehold Improvements and Refurbishments.

            (a) Tenant  shall  accept  the  Premises  in its "AS IS"  condition;
provided, however, that after the Commencement Date, Landlord shall make certain
improvements and refurbishments to the Premises as follows: Landlord shall patch
(as  necessary) and paint the walls of the Premises and shall replace the carpet
in the Premises with mutually  acceptable  commercial grade carpeting.  Any such
refurbishments and improvements shall comport with building standard.

            (b) (i) At Landlord's sole cost and expense  (subject,  however,  to
Tenant's  obligation to pay for any Excess Costs, as set forth in Section 2.3(d)
below),  Landlord  shall  contract  with  a  general  contractor  (the  "General
Contractor")  to complete  the  leasehold  improvements  and  refurbishments  in
accordance with this Section 2.2. Landlord shall bid the general contractor work
to at least three (3) general contractor bidders. Each of the general contractor
bidders shall submit a fixed price bid including  the  subcontractor  or "trade"
work, bid by the general contractor to at least three (3) subcontractor bidders.
The  selection  of the  General  Contractor  shall  be made by  Landlord  in its
commercial good faith.

                  (ii) Landlord or its  affiliate,  at no cost to Tenant,  shall
administer,  supervise and manage the  refurbishments  and  improvements  to the
Premises pursuant to this Section 2.2.

                  (iii)  Tenant has  designated  Ms.  Nancy  McKinley  to be its
construction coordinator who shall be entitled to inspect the refurbishments and
improvements  and  otherwise act on Tenant's  behalf during such time.  Tenant's
construction  coordinator  shall have full  authority  to make all  decisions on
behalf of Tenant with  respect to material or design  changes and change  orders
(to  be  documented,   submitted  to  and  executed  by  the  parties  prior  to
commencement  of such work),  and any decisions made in the field by such person
shall be binding upon Tenant. Landlord agrees that it shall cooperate, and shall
cause the General Contractor and Landlord's  construction  manager to cooperate,
with Tenant's construction coordinator. Landlord agrees that it shall not effect
change orders  without the written  approval of Tenant or Tenant's  construction
coordinator.

                  (iv) The improvements to the Premises  contemplated in Section
2.2(a) hereof shall be performed by Landlord upon  forty-five (45) days' written
notice from Tenant.

<PAGE>

            (c) The  Premises is  currently  constructed  and improved as office
space. Landlord shall maintain all life safety systems, and, except as otherwise
provided  herein,  Landlord shall comply with all requirements of all prevailing
governmental  authorities having or claiming jurisdiction over the Building, the
Project or the Common Areas concerning the same.

      Section 2.3.      Allowance

            (a)  Tenant  shall  receive a total  improvement  and  refurbishment
allowance  (the   "Allowance")   which  shall  be  applied   towards   leasehold
improvements and refurbishments as set forth in Section 2.2 (including  signage,
as set forth in Section 5.4 (c) hereof); the Allowance shall be in the total sum
of Fifty-Two Thousand Dollars ($52,000.00).

            (b) The cost of the leasehold  improvements and refurbishments shall
be paid monthly by Landlord out of the  Allowance  based upon the draw  schedule
and work in place. Tenant and Tenant's construction  coordinator shall receive a
copy of each  monthly  requisition.  It is hereby  agreed  that all  permanently
affixed leasehold improvements, if any, shall immediately become the property of
Landlord upon completion unless otherwise agreed to in writing.

            (c) In the event the total cost of the  leasehold  improvements  and
refurbishments is less than the Allowance,  Landlord shall retain such amount as
its  property  and there shall be no payment to Tenant or abatement of Rent with
respect thereto.

            (d) In the event the total cost of completing the  improvements  and
refurbishments  to the Premises shall exceed the Allowance (the "Excess Costs"),
said Excess Costs shall be paid by Tenant to Landlord in cash,  in full,  within
thirty (30) days after Landlord's demand therefor;  provided,  however,  that at
Tenant's  election such Excess Costs (but not to exceed Two Dollars  [$2.00] per
square foot of GRA in the  Premises)  may be amortized as  additional  Base Rent
over the Main Term, calculated using an interest factor of twelve percent (12%).
Attached  hereto as  Schedule I is a copy of bills  received  by  Landlord  with
respect to the performance of the initial improvements to the Premises.

            (e) Landlord  represents  and warrants that,  upon the  Commencement
Date and completion of the improvements and refurbishments to the Premises to be
performed by Landlord pursuant to Section 2.2 hereof, the Premises are and shall
be in compliance with all requirements of the Americans with Disabilities Act of
1990 (the  "ADA").  Upon  completion  of the  improvements  and  refurbishments,
Landlord  shall be  responsible  for ADA  compliance  issues with respect to the
Common  Areas and Tenant  shall be  responsible  for all ADA  compliance  issues
within the Premises.

      Section 2.4 .     [INTENTIONALLY DELETED].

      Section 2.5.      [INTENTIONALLY DELETED].

      Section 2.6.      Tenant's Occupancy of Premises.

      Within  fifteen (15) days  following  the  Commencement  Date,  Tenant and
Landlord shall execute a "Commencement  Date Notice" in the form attached hereto
as Schedule E.

<PAGE>

      Section 2.7.      Mechanics' and Other Liens.

      (a)  With  respect  to any work  performed  by  Tenant  in  furnishing  or
equipping the Premises hereunder,  and with respect to any alterations performed
pursuant  to  Section  9.4,  Tenant  will not  permit to be  created  and has no
authority  to  permit  to  be  created  or  to  remain  undischarged  any  lien,
encumbrance  or charge  (arising  out of any work done or  materials or supplies
furnished by an contractor, subcontractor,  mechanic, laborer or materialman, or
any mortgage,  security agreement or otherwise by or for Tenant), which might be
or  become a lien or  encumbrance  or  charge  upon the  Premises,  or  Tenant's
leasehold estate therein,  the Project or any income therefrom.  Tenant will not
suffer any other  matter or thing  whereby the estate,  rights and  interests of
Landlord in the Project might be encumbered or impaired.

      (b) If any  mechanics'  lien on account of any alleged debt of Tenant,  or
any person acting on Tenant's behalf,  shall be filed against the Premises,  the
Project or any income  therefrom,  Tenant  shall take and  diligently  prosecute
appropriate  action to have the same discharged or bonded and released of record
at Tenant's  sole  expense  within  thirty (30) days of the filing of such lien.
Upon  Tenant's  failure so to do,  Landlord,  in  addition to any other right or
remedy that it may have, may cause said lien to be discharged or bonded and take
such other action as may be reasonably  necessary to protect its  interest,  and
Tenant  shall pay any amounts paid by Landlord in  connection  with such action,
and all  reasonable  legal and other costs and expenses  incurred by Landlord in
connection  therewith  (including  reasonable  attorneys'  fees, court costs (if
awarded post-judgment) and other necessary disbursements). Any such amounts paid
by Landlord and the amount of any such  expenses or costs  incurred by Landlord,
if not paid by Tenant to Landlord  within thirty (30) days after the date Tenant
receives  written  notice  from  Landlord  of the amount  thereof and demand for
payment of the same,  shall,  together with interest thereon at the Default Rate
from the date of the receipt by Tenant of the  aforesaid  written  notice to the
date of payment thereof by Tenant,  be treated as Additional  Rent, and shall be
payable by Tenant to  Landlord  not later than thirty (30) days after the giving
of such written  notice and demand.  Nothing  herein  contained  shall  obligate
Tenant to pay or discharge any lien created by Landlord.

      (c) Except with respect to the initial  improvements and refurbishments to
the Premises to be performed by Landlord pursuant to Section 2.2 hereof,  Tenant
shall promptly pay all persons furnishing labor or materials with respect to any
work  performed by or on behalf of Tenant in, on or about the Premises.  No work
which Landlord permits Tenant to perform shall be deemed to be for the immediate
use and benefit of Landlord so that no mechanics' or other lien shall be allowed
against the estate of  Landlord  by reason of any  consent  given by Landlord to
Tenant to improve the Premises.  This Lease expressly provides that the interest
of Landlord shall not be subject to liens for improvements made for or on behalf
of Tenant, and Tenant shall notify each of Tenant's contractors of the foregoing
provisions.

      (d) To the extent permitted by law,  Landlord shall have the right to post
such other notices as Landlord may deem to be appropriate  for the protection of
its  interests in the Premises.  The  provisions of this Section 2.7 shall apply
with respect to any work performed by or on behalf of Tenant in, on or about the
Premises during the Term thereof.

<PAGE>

      Section 2.8.      Tenant's Property.

      (a) All trade  fixtures,  furniture and equipment (as  distinguished  from
leasehold improvements) owned by Tenant and installed in the Premises ("Tenant's
Property")  shall be and remain the property of Tenant and shall be removable at
any time,  including upon the expiration of the Term,  provided (i) Tenant shall
not at such time be in default of any term,  covenant or provision of this Lease
beyond any applicable grace, notice or cure period, and (ii) Tenant shall repair
to the satisfaction of Landlord any damage to the Premises caused by the removal
of any of Tenant's Property.

      (b) If Tenant's Property,  or any portion thereof, is not removed from the
Premises  upon the  expiration  of the Term or any earlier  termination  of this
Lease in accordance with the foregoing,  such remaining Tenant's Property shall,
at the election of  Landlord,  become the  personal  property of  Landlord,  and
Tenant's  rights  therein  shall  cease upon the  exercise  of such  election by
Landlord.

                                    ARTICLE 3

                                      TERM

      Section 3.1.      Term.

      The term of this Lease ("Term") shall include the Preliminary Term and the
Main Term.


      Section 3.2.      Preliminary Term.

      The  "Preliminary  Term"  shall  begin as of the date of this  Lease  and,
unless sooner terminated as herein provided, continue thereafter through the day
immediately prior to the Commencement Date.

      Section 3.3.      "Main Term," "Lease Year" Defined.

      (a) "Main Term" means the period  commencing on the Commencement Date and,
subject to the  provisions  of Article 14 and the other terms and  conditions of
this Lease,  continuing  for the number of years  specified in clause (a) of the
Fundamental Lease Provisions.

      (b) "Lease Year" means each  successive  twelve (12) calendar month period
commencing on the Commencement Date, as defined in Section 4.2.

      (c) It is intended  that Base Rent and any other  payments  required to be
made by Tenant  hereunder be calculated  with  reference to the Lease Year.  All
other charges for which Tenant is responsible  are to be based upon the calendar
year or partial calendar year, whichever is applicable.

      Section 3.4.      Termination.

      Unless sooner  terminated  pursuant to the provisions  hereof,  this Lease
shall  terminate  on the  expiration  of the Term  without the  necessity of any
notice from either  Landlord or Tenant to terminate the same,  and Tenant hereby
waives notice to vacate or quit the Premises and agrees that  Landlord  shall be

<PAGE>

entitled to the benefit of all remedies at law or equity  respecting the summary
recovery of possession  of the Premises from a Tenant  holding over, to the same
extent as if statutory notice had been given. For a period of twelve (12) months
prior to the  expiration of the Term,  Landlord shall have the right to show the
Premises and all parts thereof,  upon  reasonable  advance notice to Tenant,  to
prospective tenants during normal business hours.

      Section 3.5.      Holding Over.

      If Tenant shall be in possession of the Premises after the  termination of
this Lease,  in the absence of any written  agreement  extending  the Term,  the
tenancy  under this Lease shall become one from  month-to-month,  terminable  by
Landlord on thirty (30) days' prior written notice, at a monthly rental equal to
(i) one hundred fifty percent  (150%) of the sum of the monthly  installment  of
Base Rent payable during the last calendar month of the Term, plus (ii) Tenant's
Operating  Charge and Tenant's Taxes as otherwise  calculated  hereunder for any
such month.  Tenant shall also pay as Additional  Rent all other charges payable
under the terms of this  Lease,  prorated  for each month  during  which  Tenant
remains in possession. Such month-to-month tenancy shall be subject to all other
conditions, provisions and obligations of this Lease. Tenant shall not interpose
any counterclaims in a summary proceeding or other action based on holdover.  At
any time after a termination under this Section becomes effective,  Landlord may
reenter and take  possession of the  Premises,  any rule of law or equity to the
contrary notwithstanding.

                                    ARTICLE 4

                                      RENT

      Section 4.1.      Tenant's Agreement to Pay Rent.

      Tenant hereby agrees to pay to Landlord  during the Term, at the times and
in the manner herein provided, Base Rent, as may be increased from time to time,
and Additional  Rent  (collectively,  "Rent").  Tenant's  obligation to pay Rent
during the Term shall survive the termination of this Lease.

      Section 4.2.      Commencement Date.

      "Commencement  Date"  means (i)  October  6,  1999,  with  respect  to the
Premises  Portion #1 and the  Premises  Portion  #2; and (ii) May 1, 1999,  with
respect to the Premises Portion #3.

      Section 4.3.      Base Rent.

      For the first Lease Year during the Term,  Tenant  shall pay  Landlord the
annual  Base  Rent  amount  set  forth in clause  (g) of the  Fundamental  Lease
Provisions  ("Base  Rent"),  which shall be payable in twelve (12) equal monthly
installments,  in  advance,  on the  first  (1st)  day of  each  calendar  month
(provided,  however,  that Base Rent with respect to the Premises Portion #1 and
Premises  Portion #2 for the partial month  commencing on October 6, 1999, shall
be due and payable on or before October 6, 1999).

<PAGE>

      Section 4.4.      Annual Rent Increase.

      For each Lease Year during the Term after the first Lease Year, the annual
Base Rent shall be that amount which is the sum equaling the product obtained by
multiplying  the Base Rent for the  immediately  preceding Lease Year by 103%. A
schedule of the Base Rent  increases  is found at clause (g) of the  Fundamental
Lease Provisions. With respect to the Premises Portion #3, the first annual Base
Rent increase shall be effective on October 6, 2000, i.e. the first  anniversary
of the  Commencement  Date  with  respect  to the  Premises  Portion  #1 and the
Premises  Portion  #2; to the end that the Base Rent rate shall be the same with
respect to the entire Premises at all times during the Term of the Lease.

      Section 4.5.      Additional Rent.

      In  addition  to Base  Rent,  Tenant  shall pay all other sums of money or
charges of whatever nature required to be paid by Tenant to Landlord pursuant to
this  Lease  (collectively,  "Additional  Rent"),  whether  or not the  same are
designated as Additional  Rent. Any Additional Rent accruing under any provision
of this Lease shall,  except as is otherwise set forth in this Lease, be due and
payable  in the  installment  of the Base Rent the next  falling  due after such
Additional  Rent  accrues  becomes due and payable,  unless the  Landlord  makes
written demand upon the Tenant for payment thereof at any earlier time, in which
event such Additional Rent shall be due and payable at such time.

      Section 4.6.      Payment of Rent.

      Except as otherwise  provided  herein,  Tenant shall pay all Rent when due
and payable,  without any set-off,  deduction,  notice or prior demand  therefor
whatsoever.  If Tenant shall fail to pay any Rent within ten (10)  business days
after the same is due,  Tenant shall be  obligated to pay a late payment  charge
equal to the greater of (a) One  Hundred  Dollars  ($100.00)  or (b) ten percent
(10%) of any Rent  payment  not paid when due,  to  reimburse  Landlord  for its
additional administrative costs. Rent and any reports and statements required of
Tenant  shall be paid and  delivered  to Landlord at the  designated  management
office in the  Project  between  the hours of 8:00 a.m.  and 6:00  p.m.,  Monday
through Friday (except  holidays),  or at such other place as Landlord may, from
time to time,  designate  in a notice  to  Tenant.  Any  payment  by  Tenant  or
acceptance  by Landlord of a lesser amount than shall be due shall be treated as
a payment on account.  The acceptance by Landlord of a check for a lesser amount
with an endorsement  thereon,  or upon any letter  accompanying such check, that
such lesser amount is payment in full shall be given no effect, and Landlord may
accept  such check  without  prejudice  to any other  rights or  remedies  which
Landlord may have against Tenant.

      Section 4.7.  Interest Charge.

      In addition to any late payment  charge which might  otherwise be due, any
Rent  payable  by Tenant  under  this Lease that is not paid when due shall bear
interest  at the Default  Rate from the first day due until such Rent,  plus all
interest accrued thereon, are paid in full.

<PAGE>

      Section 4.8.  Security Deposit.

      As a security deposit ("Security  Deposit"),  Tenant, at Tenant's expense,
and on or before the Commencement  Date with respect to the Premises Portion #3,
shall deliver to and deposit with Landlord an irrevocable  unconditional  letter
of credit (the "Letter of Credit")  drawn on  NationsBank  and  redeemable  upon
presentation at a location in New York City,  naming Landlord as the beneficiary
thereof and otherwise in form and substance  reasonably  acceptable to Landlord,
to be held as security for the payment of any Rent (including  Additional  Rent)
payable by Tenant and for the faithful  performance  of all  covenants of Tenant
hereunder.  The original  principal  amount of the Letter of Credit shall be One
Hundred Seventy-Eight Thousand Dollars  ($178,000.00),  and the Letter of Credit
shall remain issued and  outstanding  throughout  the Term;  provided,  however,
that,  absent an Event of Default by Tenant which remains  outstanding after any
applicable  notice,  grace or cure period, the principal amount of the Letter of
Credit may be reduced at the  beginning of each of the second,  third and fourth
Lease  Years with  respect to Premises  Portion #3 by an amount  equal to twenty
percent (20%) of the initial principal amount (i.e., $35,600.00).  The Letter of
Credit  shall  provide  Landlord  with not less than thirty (30) days' notice of
expiration,  cancellation,  renewal or non-renewal thereof. Tenant shall deliver
to Landlord  evidence of any renewal thereof within ten (10) business days prior
to the expiration thereof; a failure of Tenant to obtain a renewal of the Letter
of Credit or post satisfactory  substitute collateral hereunder shall constitute
an Event of Default hereunder.  Upon the occurrence of an Event of Default,  the
Security Deposit may, at Landlord's option, be applied on account of the default
up to the amount  reasonably  needed to cure such an Event of Default.  Landlord
shall deliver the Letter of Credit to any  purchaser of  Landlord's  interest in
the Premises, in the event that such interest be sold; and, thereafter, Landlord
shall be discharged from any further liability with respect thereto,  and Tenant
agrees to look solely to such purchaser for the return of the Security Deposit.

                                    ARTICLE 5

                                       USE

      Section 5.1.  Prompt Occupancy and Use.

      Tenant shall occupy the Premises  upon  commencement  of the Main Term and
thereafter shall continuously  occupy and use the Premises for the permitted use
as set forth in clause (i) of the Fundamental Lease Provisions ("Permitted Use")
and for no other  purpose  whatsoever  without  the  prior  written  consent  of
Landlord.  If Tenant abandons any portion of the Premises at any time during the
Term,  then  Landlord  shall be entitled (but not  obligated) to terminate  this
Lease;  provided,  that if Tenant is not  otherwise in default  hereunder,  then
Landlord shall not be entitled to accelerate  Rent or collect any damages beyond
the date of termination.

      Section 5.2.  Operating Hours.

      The operating hours for office tenants at the Building are 8:00 a.m.
until 6:00 p.m. Mondays through Fridays and 8:00 a.m. until 1:00 p.m.
Saturdays, legal holidays excepted.



<PAGE>


      Section 5.3.  Operational Requirements.

      (a) A schedule of standard  building  services to be performed or provided
by Landlord at, to or within the Building is attached  hereto as Schedule B. The
cost of providing or performing  the services are included  within the Base Rent
to be paid by Tenant pursuant to the terms of this Lease.

      (b) In regard to the use and occupancy of the Premises,  Tenant shall,  at
Tenant's  expense:  (i) keep the  inside and  outside of all glass  doors of the
Premises clean;  (ii) replace promptly any cracked or broken glass with glass of
like kind and  quality;  (iii)  maintain  the  Premises in a clean,  orderly and
sanitary  condition;  (iv) keep all  mechanical  apparatus free of vibration and
noise which may be transmitted  beyond the interior of the Premises;  (v) comply
with all  federal,  state,  county  and city  laws,  ordinances,  codes,  rules,
regulations and reasonable  recommendations  of Landlord's insurer or applicable
fire insurance rating organizations now or hereafter in effect; (vi) comply with
and observe all rules and regulations  established by Landlord from time to time
for the Building,  a copy of which current  rules and  regulations  are attached
hereto as  Schedule  F; and (vii)  conduct  its  business  in all  respects in a
dignified  manner in  accordance  with the highest  standards  of a  first-class
office  project  in  the  Tysons  Corner,  Virginia  area.  Notwithstanding  the
foregoing,  Tenant  shall  have no  obligation  to make any  alterations  to the
Premises,  whether  structural or otherwise,  unless such  obligation  hereunder
arises as a result of the use or occupancy thereof by Tenant for any purpose not
authorized as a Permitted Use herein or the conduct by Tenant of its business in
the Premises in a manner  different from the ordinary and proper conduct of such
business.

      (c) In regard to the use and  occupancy  of the  Premises  and the  Common
Areas,  Tenant  shall not;  (i) place or  maintain  any  trash,  refuse or other
articles in any vestibule, service corridor or entry way of the Premises, on the
footwalks or any corridors  adjacent thereto or elsewhere on the exterior of the
Premises so as to obstruct any  driveway,  corridor or any other  Common  Areas;
(ii) permit the parking of vehicles so as to unreasonably interfere with the use
of any Common  Area or other  area  within the  Project;  (iii)  receive or ship
articles of any kind outside the designated  loading area for the Project;  (iv)
obstruct the Common Areas adjacent to the Premises; (v) use or permit the use of
any portion of the Premises in a manner  likely to injure the  reputation of the
Project  or  which  will be in  violation  of law,  nor  permit  any part of the
Premises to be used for any unlawful, disreputable or immoral purpose whatsoever
or  for  any  other  activity  of a  type  which  is  not  generally  considered
appropriate  for urban office centers  conducted in accordance  with the highest
standards  of  operation;  (vi)  use or  permit  the use of any  portion  of the
Premises for any activity  which  constitutes a nuisance or is hazardous;  (vii)
place a load upon any floor  which  exceeds  the floor  load which the floor was
designed to carry; or (viii) operate its heating or  air-conditioning  in such a
manner as to drain heat or  air-conditioning  from the Common  Areas or from the
premises of any other tenant or other occupant of the Project.

      Section 5.4.  Signs; Painting; Displays.

      (a)  Tenant  shall not place or suffer to be placed or  maintained  on the
exterior of the Premises any signs, advertising matter or any other thing of any
kind,  and Tenant will not place or maintain  any matter on any window,  door or

<PAGE>

other  portions  of the  Premises  in such a manner  as to be  visible  from the
exterior of the  Premises,  unless  otherwise  approved in writing by  Landlord.
Tenant  shall,  at its expense,  maintain any such sign or other thing as may be
permitted hereunder in good condition and repair at all times.

      (b) Tenant  shall not paint or  decorate  any part of the  exterior of the
Premises, or any part of the interior visible from the exterior thereof, without
first obtaining Landlord's approval.

      (c) Landlord  maintains a Building directory in the lobby of the Building,
and Landlord  shall  maintain  Tenant's pro rata share of the  directory  strips
(being two [2]  strips)  identifying  Tenant and such of Tenant's  employees  as
Tenant may designate  from time to time.  The cost of initial  installation  and
maintenance of the directory  listings  allocated to Tenant at initial occupancy
shall be borne by  Landlord;  any costs of  changing  the  listings  at Tenant's
request  from time to time  shall be borne by  Tenant.  Landlord  shall  provide
Tenant with building  standard suite entry signage and partial floor directional
signs with respect to the Premises  Portion #1, the Premises  Portion #2 and the
Premises Portion #3; the cost thereof shall be paid for out of the Allowance.

                                    ARTICLE 6

                                      TAXES

      Section 6.1.  Real Estate Taxes.

      (a) Beginning  January 1, 2000,  and continuing  thereafter,  Tenant shall
pay, as Additional Rent,  Tenant's  proportionate share of the increases for the
remainder  of the Term in all Taxes over those  Taxes paid by  Landlord  for the
Project with respect to calendar  year 1999 (the "Base  Year").  As used herein,
"Taxes" shall mean amounts payable by Landlord with respect to personal property
taxes  (excluding  any personal  property taxes of the Landlord for equipment or
items not used  directly  in the  operation  or  maintenance  of the  Building),
intangible  taxes,  real estate  taxes,  ad valorem  taxes,  general and special
assessments,  taxes on real estate rental  receipts,  taxes on Landlord's  gross
receipts,  or any other Tax imposed  upon or levied  against real estate or upon
owners of real estate rather than persons generally,  payable with respect to or
allocable to the Project (including, but not limited to, any payments in lieu of
any Taxes,  and fees of attorneys,  consultants and appraisers in contesting any
Taxes).

      (b) The amount of Tenant's  proportionate  share of the  increase in Taxes
over  the  Base  Year  (which  proportionate  share of the  increase  is  called
"Tenant's Taxes") shall be computed by multiplying the amount of the increase in
such Taxes over those  Taxes paid or  incurred  for the Base Year by the GRA Tax
Fraction. In the last Lease Year of the Term, the provisions of this Section 6.1
shall apply, but Tenant's liability for its proportionate  share of the increase
in Taxes for such year shall be subject to a pro rata adjustment  based upon the
number of days of such Lease Year falling  within the calendar year in question.
Tenant expressly agrees that Tenant shall have no right to appear or contest any
Taxes  assessed,  allocated  or imposed  with  respect to the Project and Tenant
hereby expressly waives any and all rights now or hereafter conferred upon it by
law to independently contest any Taxes.

      (c) Taxes shall not  include:  (i) federal,  state or local income  taxes;
(ii)  franchise,   gift,  transfer,   capital  stock,  estate,   succession,  or

<PAGE>

inheritance  taxes;  (iii)  penalties or interest for late payment of Taxes;  or
(iv) any  increases in Taxes which result solely from the creation of additional
rentable  area  in the  Project  or in the  Building  or  from  improvements  or
alterations  made by Landlord or other  tenants.  Any  increase in Taxes for the
Building, land or Project resulting from a refinancing or sale shall be added to
the Base Year.

      (d) If the Taxes are phased in during the Lease  Term for any  reason,  or
should the Taxes be abated or reduced,  for any reason,  for the Base Year, then
the Taxes for the Base Year shall be adjusted  so that they are  computed on the
same tax basis as those Taxes for Lease Years in which the  phase-in,  abatement
or reduction did not occur. In addition,  if Landlord  receives a tax refund for
any Lease Year or partial Lease Year during the Term,  Landlord shall deliver to
Tenant its pro rata share of any such refund.

      Section 6.2.  Payment of Tenant's Taxes.

      (a)  Tenant's  Taxes shall be paid by Tenant in twelve (12) equal  monthly
installments  in advance in such  amounts as are  estimated  and billed for each
applicable  Lease Year by  Landlord,  each such  installment  being due with the
monthly installment of Base Rent.

      (b) Within  sixty (60) days  after the date upon which  Landlord  shall be
obligated  to  pay  any  Tax  or  Taxes,   or  such  reasonable  (in  Landlord's
determination)  time thereafter,  Landlord shall certify to Tenant the amount of
Taxes  allocated  and  assessed  for the  period in  question  and the amount of
Tenant's  proportionate  share thereof.  The proportionate share paid or payable
for each such period shall be adjusted between Landlord and Tenant,  the parties
hereby  agreeing  that Tenant  shall pay  Landlord or Landlord  shall  credit to
Tenant's account,  or (if such adjustment is at the end of the Term) pay Tenant,
as the  case  may be,  within  thirty  (30)  days of  Tenant's  receipt  of such
certification, such amounts as may be necessary to effect such adjustment to the
agreed  upon  proportionate  share.  The  failure of  Landlord  to provide  such
certification  within the time prescribed  above shall not relieve Tenant of its
obligations  generally or for the specific  Lease Year in which any such failure
occurs.

      Section 6.3.      Taxes on Rent and Other Taxes.

      In addition to Tenant's  Taxes,  Tenant shall pay to Landlord (if Landlord
is  required by law to collect,  or has any  liability  for the payment of, such
taxes) any  excise or other tax which may in the  future be  levied,  imposed or
assessed by any  governmental  authority or other taxing authority upon any Rent
payable hereunder  (collectively,  "Rental Tax"); provided,  that if such Rental
Tax is assessed in lieu of the Taxes, than the amount of Taxes paid for the Base
Year shall be deducted  from the total  Rental Tax prior to the  calculation  of
Tenant's  proportionate  share  thereof.  Tenant  shall pay such  Rental  Tax to
Landlord  with  each  payment  of Rent  (including  payments  of Base  Rent  and
Additional Rent). Tenant shall also pay, prior to the time the same shall become
delinquent  or payable with  penalty,  all personal  property  taxes  imposed on
Tenant's  furniture,   trade  fixtures,   apparatus,   equipment  and  leasehold
improvements  installed by Tenant or by Landlord on behalf of Tenant  (except to
the extent such leasehold  improvements shall be covered by Taxes referred to in
Section 6.1 hereof), and except as otherwise  specifically  provided for herein,
and any other property of Tenant.  Landlord may require that Tenant's  leasehold
improvements be separately assessed by the taxing authority.


<PAGE>

                                    ARTICLE 7

                                  COMMON AREAS

      Section 7.1.      Use and Management.

      (a) Upon the express agreement of Tenant that it will use the Common Areas
in harmony with  Landlord,  other tenants and licensees of other portions of the
Project,  Landlord grants to Tenant and its agents,  employees and customers,  a
non-exclusive  license to use the Common Areas, subject to the exclusive control
and  management  thereof at all times by  Landlord,  and subject  further to the
rights of Landlord set forth in the next paragraph.

      (b)  Landlord  shall  operate and  maintain,  or cause to be operated  and
maintained,  any areas designated by Landlord as Common Areas in a manner deemed
by Landlord to be  consistent  with  first-class  office  projects in the Tysons
Corner,  Virginia, area. Landlord shall have the right from time to time to take
the  following  actions:  (i)  to  establish,   modify  and  enforce  rules  and
regulations  governing the use and  operation by all tenants,  including but not
limited to Tenant,  in, on,  about,  or with  respect to the Common  Areas which
Landlord  shall deem necessary or desirable in order to assure the highest level
of quality and  character of operation  of the Common  Areas;  (ii) to add to or
subtract from the Common Areas, provided that the ingress to and egress from the
Premises  shall not be materially and adversely  affected;  (iii) to enter into,
modify or terminate  easements  and other  agreements  pertaining to the use and
maintenance of the Common Areas, and any portions thereof;  (iv) to close any or
all  portions  of the  Common  Areas to such  extent as may,  in the  opinion of
Landlord,  be necessary  to prevent a  dedication  thereof or the accrual of any
rights by any person or by the public therein;  (v) to close  temporarily any or
all portions of the Common Areas; and (vi) to do and perform such other acts in,
on, to and with respect to the Common Areas and improvements  therein as, in the
exercise of good business  judgment,  Landlord shall reasonably  determine to be
advisable or necessary.

      Section 7.2.      Operating Costs Defined.

      (a)  "Operating  Costs" means any and all costs and  expenses  incurred by
Landlord for  services  performed by Landlord or by others on behalf of Landlord
with respect to the  operation  and  maintenance  of the  Project,  the Building
(including  the Premises)  and the Common Areas  located  therein and serving or
allocable to the Project or the Building,  including, without limitation, except
as specifically set forth herein, all costs and expenses of:

            (i) operating, maintaining,  repairing, lighting, signing, cleaning,
removing  trash,  painting,  striping,  controlling  of traffic,  controlling of
rodents,  and  policing  and  securing  the  Common  Areas  (including,  without
limitation,  the costs of uniforms,  equipment,  assembly permits,  supplies and
alarm systems);

            (ii)  purchasing  and  maintaining  in full force  insurance for the
Project (including, without limitation, liability insurance for personal injury,
death and property  damage,  rent insurance,  insurance  against fire,  extended
coverage,  theft or other casualties,  worker's compensation  insurance covering
personnel,  fidelity  bonds  for  personnel,  insurance  against  liability  for
defamation  and claims of false arrest  occurring  on or about the Project,  and
plate glass insurance);

<PAGE>

            (iii) removing snow, ice, water and debris;

            (iv)  operating,  maintaining  and repairing  machinery,  furniture,
accessories  and equipment used in the operation and maintenance of the Project,
and the personal  property taxes and other charges  incurred in connection  with
such  machinery,  furniture,  accessories  and  equipment  except  as  otherwise
specifically excluded herein;

            (v) maintaining and repairing  paving,  curbs,  walkways,  drainage,
pipes,  ducts,  conduits,  grease traps,  and lighting  fixtures  throughout the
Project;

            (vi) planting and replanting  flowers,  shrubbery,  trees, grass and
planters;

            (vii)  providing,  electricity  and  heating,  ventilation  and  air
conditioning  to the  Project  and  operating,  maintaining  and  repairing  any
equipment used in connection therewith (to the extent not specifically  excluded
from Operating Costs);

            (viii) water and sanitary sewer services and other services, if any,
furnished to the Project for the non-exclusive use of tenants;

            (ix) enforcing any operating agreements pertaining to the Project or
any portions thereof,  and any easement and/or rights agreements entered into by
Landlord  for  the  benefit  and  use of all  tenants  of  the  Project,  or any
arbitration or judicial actions undertaken with respect to the same;

            (x)  maintaining  and  repairing  the  Project,  including,  without
limitation, exhaust systems, sprinkler systems, pumps, fans, switchgear, loading
docks and ramps,  freight elevators,  passenger elevators,  stairways,  services
corridors, delivery passage, utility plants, transformers, doors, walls, floors,
skylights, ceiling and windows; and

            (xi) audits,  management fees and expenses,  payroll,  payroll taxes
and employee benefits of all on-site personnel  including,  without  limitation,
security and maintenance  personnel,  secretaries  and  bookkeepers  (including,
specifically,  uniforms  and working  clothes and the cleaning  thereof,  tools,
equipment and supplies used by such  personnel,  and the expenses  imposed on or
allocated to Landlord or its agents  pursuant to any  collective  bargaining  or
other agreement) and management office rent.

      (b) By way of illustration  and not  limitation,  Operating Costs (for the
Building,  Common Areas or the Project,  whether or not  specifically set forth)
shall not include, among other expenses or costs, any expenses or costs incurred
or paid by Landlord for the following items:

            (i) "Capital  Expenditures",  which include any capital replacement,
capital  repair,   capital  improvement  or  major  structural   restoration  or
correction made to the Building,  the Common Areas,  the land or the Project and
any other  expense  which  would be deemed  to be a  capital  expenditure  under
generally accepted  accounting  principles,  consistently  applied but excluding
those capital  expenditures  intended and reasonably expected to reduce the cost
of operating the  building,  which may be included in Operating  Costs.  Capital
Expenditures of $1,000 or less may be included in Operating Costs;

<PAGE>
            (ii)  Depreciation or  amortization of the Project,  the Building or
their contents or components;

            (iii)  Expenses  for the  preparation  of space or other  work which
Landlord  performs for any tenant or  prospective  tenant of the Building or the
Project;

            (iv) Interest,  amortization  or other costs,  including legal fees,
associated with any mortgage,  loan or refinancing of the Project, the land, the
Building, or the Common Areas;

            (v)  The  cost  of any  item  or  service  which  Tenant  separately
reimburses  Landlord  or pays  to  third  parties,  or  that  Landlord  provides
selectively  to one or more tenants of the  Building or the Project,  other than
Tenant,  whether or not Landlord is  reimbursed  by such other  tenant(s).  This
category shall include the actual cost of real estate taxes separately billed to
other  tenants,  or  any  special  electrical,   heating,   ventilation  or  air
conditioning  required by any tenant that exceeds normal  building  standards or
that is required during times other than the business hours;

            (vi) Any amount paid to an entity or individual  related to Landlord
which exceeds the amount which would be paid for similar goods or services on an
arms' length basis between unrelated parties;

            (vii) Leasing commissions paid to lease space in the Project;

            (viii)  Advertising and marketing costs to attract potential tenants
for leasing of the Project;

            (ix)  Wages,   salaries  and  other  compensation  to  employees  or
officers,  directly  or  indirectly,  who  are  not  actively  involved  in  the
management  of the  Project,  except  where  payment is made for  specific  work
performed in the Project;

            (x) The  cost of any  item or  expenditure  for  which  Landlord  is
reimbursed or compensated by insurance or warranties;

            (xi)  Landlord's income taxes;

            (xii) Legal fees and expenses of Landlord for collection of rent and
other amounts due Landlord from other tenants;

            (xiii)  Expenses  resulting  from the  negligent or tortious acts of
Landlord or its agents or employees; or

            (xiv) Any other  cost or expense  which,  under  generally  accepted
accounting  principles  consistently  applied,  would not be considered to be an
Operating Cost of the Project.

      Section 7.3.      Tenant's Operating Costs Charge.

      (a) (i)  Beginning  January 1, 2000,  and  continuing  thereafter  for the
remainder  of the Term,  Tenant  shall pay to Landlord,  as  Additional  Rent, a
proportionate  share of the  increases to Operating  Costs over those  Operating
Costs incurred by Landlord for the Project during the Base Year,  which share of
such  increases  ("Tenant's  Operating  Costs  Charge")  shall  be  computed  by
multiplying  the  increases in Operating  Costs for the period in question  over
those Operating Costs incurred for the Base Year by the GRA Fraction.

<PAGE>

            (ii)  Tenant's  Operating  Costs  Charge  shall be paid by Tenant in
monthly  installments  in such amounts as are  estimated and billed by Landlord,
each installment being due with the monthly Base Rent installment.

      (b) If at any time  during  the  Lease  Term,  less  than 95% of the total
rentable area of the Project is leased by tenants,  or Landlord is not supplying
services to 95% of the total rentable area of the Project at any time during any
calendar  year,  the Operating  Costs for such calendar year shall be reasonably
determined to be an amount equal to the expenses that would normally be expected
to be incurred had such  occupancy  been 95% of the total  rentable  area of the
Project and had Landlord been  supplying  services to 95% of the total  rentable
area of the Project  throughout the calendar year. The only costs which shall be
adjusted in this manner shall be variable  expenses where the amount is directly
related to the level of  occupancy  or square foot area  receiving a  particular
service.  Landlord will indicate  which expenses were adjusted in this manner in
the Operating Costs statement.

      (c) If a new  category  of expense is  incurred  after the Base Year,  the
first full year's  expense for such item shall be added to the  Operating  Costs
for the Base  Year,  commencing  with the  first  full  calendar  year that such
expense is  incurred,  so that Tenant  shall only be required to pay  subsequent
increases in such expense.

      (d) Within one hundred  twenty (120) days (or such  additional  time as is
reasonable  under the  circumstances)  after the end of each  such  Lease  Year,
Landlord shall deliver to Tenant an itemized statement broken down in categories
with reasonable  detail of the Operating Costs for such period,  and the monthly
installments paid or payable shall be adjusted between Landlord and Tenant,  the
parties hereby  agreeing that Tenant shall pay Landlord or Landlord shall credit
Tenant's  account (or if such  adjustment is at the end of the Term, pay Tenant,
as the case may be), within thirty (30) days of receipt of such statement,  such
amounts as may be necessary  to effect  adjustment  to the agreed  proportionate
share for such Lease Year.  The failure of  Landlord to provide  such  statement
within the time  prescribed  above shall not relieve  Tenant of its  obligations
generally or for such period in which any such failure occurs.

      (e) The Operating  Costs and the books and records of Landlord for a Lease
Year,  including  those for the Base Year, may be audited by Tenant's  certified
public accountant or other authorized  representative,  at Landlord's designated
management  office during normal  business  hours,  upon at least ten (10) days'
prior notice to Landlord,  at any time during the Lease Year following the Lease
Year that is the subject of such audit.

      (f)  If  Tenant  challenges  Landlord's  computations  of  the  Base  Year
Operating  Costs,  the amount of  Operating  Costs or Taxes,  Tenant  shall give
Landlord  notice  stating  Tenant's  objections.  If Tenant's audit of Operating
Costs or Taxes for the Base Year or any  subsequent  year  indicates that Tenant
was  overcharged  for the same and  Landlord  is in  agreement,  Landlord  shall
promptly, but within thirty (30) days, repay all such overpayments to Tenant and
adjust  Tenant's  Base Year, if  necessary.  If Tenant's  audit of the Operating
Costs  for the Base  Year or any  subsequent  year  indicates  that  Tenant  was
overcharged for the Operating Costs or Taxes, by an amount which is greater than
or equal to five  percent  (5%) of the  amount  which  should  have been paid by
Tenant,  Landlord shall promptly reimburse Tenant for all of Tenant's actual and
reasonable costs associated with the audit.

<PAGE>

      Section 7.4.      Parking.

      (a) Tenant  acknowledges  that it has been  advised by  Landlord  that the
Building  includes a multi-level  parking garage operated by a third party other
than Landlord (the "Parking Garage").

      (b) During the Main Term, Landlord shall cause the Parking Garage operator
to provide to Tenant, at the then-prevailing  market rate specified from time to
time by the Parking  Garage  operator  (and  verified  in  writing,  at Tenant's
expense,  by an  independent  third-party  mutually  acceptable  to Landlord and
Tenant),  parking  spaces  based on the  parking  ratio of 3.5  spaces per 1,000
rentable square feet of the Premises (i.e., sixty-five (65) spaces). The current
market rate charged by the parking garage operator is Fifty Dollars ($50.00) per
space per month.  The parking  spaces shall be located within the Parking Garage
for Tenant's non-exclusive use. Parking spaces shall be available and accessible
to Tenant for Tenant's use  twenty-four  (24) hours per day,  seven (7) days per
week.

      (c) Landlord hereby reserves the right,  but shall have no obligation,  to
establish  a  parking  validation  system  for the  Project  pursuant  to  which
customers  and patrons of all  tenants in the Project  shall be entitled to park
within  the  Parking  Garage at  reduced  rates,  provided  that  they  obtain a
validation  stamp from one or more of the  tenants  within the  Project.  In the
event that Landlord shall  establish such a parking  validation  system,  Tenant
hereby agrees to  participate  in such Parking  Validation  System in accordance
with the rules and regulations  established by Landlord,  and to pay to Landlord
its  proportionate  share of the costs and  expenses  thereof,  which  costs and
expenses shall be included in Operating Costs.

      Section 7.5.      Overtime HVAC.

      Landlord  shall provide HVAC services to the Premises  during the hours of
8:00 a.m. through 6:00 p.m.,  Monday through Friday,  and 8:00 a.m. through 1:00
p.m. on Saturdays,  legal holidays excepted.  Landlord will use its commercially
reasonable  efforts to provide  such  services  within  the  reasonable  maximum
allowable temperatures  commensurate with first class office space in the Tysons
Corner,  Virginia area. Landlord shall, at Tenant's request and expense, upon 24
hours'  notice,  furnish HVAC  services to the Premises  during hours other than
those stated above.
                                    ARTICLE 8

                              ENVIRONMENTAL MATTERS

      Section 8.1.  Environmental Covenants.

      In its use of the Premises and the remainder of the Building,  the Project
and the land,  Tenant  shall not (either  with or without  negligence)  cause or
permit the escape,  disposal or release of any biologically or chemically active
or other hazardous substances or materials,  or allow the storage or use of such
substances or materials in any manner, or allow any such materials or substances
to be brought onto the Project or the land.

      Section 8.2.      Environmental Laws.

      For the purposes of this Lease, "hazardous substances and materials" shall
include,  without limitation those described in the Comprehensive  Environmental

<PAGE>

Response, Compensation and Liability Act of 1980, as amended (42 U.S.C. sections
9601 et seq.), the Resource Conservation and Recovery Act, as amended (42 U.S.C.
sections 6901 et seq.),  any applicable state or local laws, and the regulations
adopted under these acts.

      Section 8.3.      Indemnity.

      If any lender or  governmental  agency ever requires  testing to ascertain
whether or not there has been any release of hazardous materials on the Premises
while  this  Lease  is in  effect,  then  Tenant's  proportional  share  of  the
reasonable  costs  thereof  shall be  reimbursed  by the Tenant to Landlord upon
demand as additional charges if such requirement applies to the Premises. Tenant
shall  execute  affidavits,  representations  and the like  from time to time at
Landlord's request  concerning  Tenant's best knowledge and belief regarding the
presence of hazardous  substances  or materials  on the  Premises.  Tenant shall
defend,  indemnify and hold harmless  Landlord  against and from any  liability,
claim of liability or expense arising out of any release of hazardous substances
or materials on the Premises occurring while Tenant is in possession thereof, or
elsewhere if caused by Tenant or any person acting under Tenant.

      Section 8.4.      Pre-existing Conditions.

      Notwithstanding  anything  contained herein to the contrary,  Tenant shall
not be liable, and shall have no obligation to indemnify Landlord,  with respect
to the  environmental  conditions of the Premises  existing at the  Commencement
Date, and Tenant shall not be liable or responsible  for escalation or Operating
Costs  or  direct   reimbursement   obligations  for  remediation  of  any  such
pre-existing conditions.


      Section 8.5.      Survival.

      The  foregoing   covenants   shall  survive  the   expiration  or  earlier
termination of this Lease.

                                    ARTICLE 9

                      MAINTENANCE, REPAIRS AND ALTERATIONS

      Section 9.1.      Landlord's Duty to Maintain Structure.

      Landlord  shall use its best efforts to maintain or cause to be maintained
the structure of the Building and shall be  responsible  for: (a) repairs to any
sprinkler  system or HVAC  system  installed  by or on behalf  of  Landlord  and
serving  the  Premises,  and  (b)  structural  repairs  to the  exterior  walls,
structural columns and structural floors which collectively enclose the Premises
(excluding,  however,  all doors,  door frames,  sliding doors,  windows and any
glass therein);  provided (i) Tenant shall give Landlord notice of the necessity
for such repairs, and (ii) the necessity for such repairs shall not have arisen,
in whole or in part, from the negligence or willful acts or omissions of Tenant,
its  agents,  concessionaires,   officers,  employees,  licensees,  invitees  or
contractors.

      Section 9.2.      Tenant's Duty to Maintain Premises.


<PAGE>

      (a) Tenant  shall,  at all times from and after  delivery of possession of
the Premises to Tenant,  at its own cost and  expense,  maintain the Premises in
good and tenantable condition, and Tenant shall make all repairs to the Premises
or  any   installations,   equipment  or  facilities  therein  (except  for  any
maintenance and repairs required to be made by Landlord  pursuant to Section 9.1
or  reconstruction  required to be made by Landlord  pursuant to Section  11.1).
Without  limiting the  generality of the foregoing,  Tenant shall:  (i) keep the
interior of the  Premises,  together  with all  electrical,  plumbing  and other
mechanical  installations  therein,  in good order and repair and shall make all
replacements  thereof  from time to time  required  by any  governmental  agency
having jurisdiction thereover;  (ii) surrender the Premises at the expiration of
the Term or at such other time as Tenant  may  vacate  the  Premises  in as good
condition as when received, except for (A) ordinary wear and tear, (B) damage by
Casualty  (other than such damage by  Casualty  which is caused,  in whole or in
part,  by the  negligence  or willful acts or  omissions of Tenant,  its agents,
concessionaires,  officers,  employees,  licensees,  invitees or contractors and
which is not wholly covered by Landlord's hazard insurance policy),  or (C) acts
of God; and (iii) take care not to overload the  electrical  wiring  serving the
Premises  or within the  Premises,  and install at its  expense,  subject to the
provision of Section 9.4, any additional electrical, mechanical, plumbing or any
other  equipment  which may be required in connection  with the  Permitted  Use.
Except for the  provisions  of  Section  9.3  hereof,  nothing  herein  shall be
construed  to require  Tenant to  maintain  or make any  repairs  outside of the
Premises or to the  structural  components of the Building  passing  through the
Premises or any building systems found therein.

      (b) Any damage or injury  sustained by any person  because of  mechanical,
electrical, plumbing or any other equipment or installation, the maintenance and
repair of which is the  responsibility  of Tenant  pursuant to this Section 9.2,
shall be paid for by Tenant,  and Tenant shall  indemnify  and hold Landlord and
any  Mortgagee  harmless  from and  against  all  claims,  actions,  damages and
liabilities in connection therewith,  including,  but not limited to, attorneys'
and other  professional fees and any other costs which Landlord or any Mortgagee
incurs by reason  thereof,  regardless of whether formal legal  proceedings  are
instituted.

      Section 9.3.      Tenant's Duty to Repair Damage.

      Tenant shall repair promptly,  at its expense,  any damage to the Premises
(and upon  demand,  shall  reimburse  Landlord for the cost of the repair of any
damage  occurring  elsewhere  in  the  Project),   caused  by  Tenant,  Tenant's
contractors,  Tenant's suppliers,  independent contractors,  agents,  employees,
concessionaires  or licensees or any other persons in bringing into the Premises
any  property  for  Tenant's  use,  or by the  installation  or  removal of such
property,  regardless  of fault or by whom such damage  shall be caused  (unless
caused solely by Landlord, its agents, employees or contractors). Any repairs or
alterations  to the Premises which may affect the structure or appearance of the
Premises,  any Common Areas or any portion of the Building or the Project, shall
require the prior written  consent  thereto by Landlord and Landlord  shall have
the absolute  right to withhold its consent and require  alternative  methods of
repair and  alteration if the making  thereof  will,  in  Landlord's  reasonable
opinion,  adversely  affect the Premises,  the Common Areas, the Building or the
Project.  In default of the making of such repairs by Tenant,  at the expiration
of ten (10) calendar days after notice to Tenant, Landlord may make such repairs
or cause the same to be made,  and  Tenant  agrees to pay to  Landlord  the cost
thereof  promptly upon Landlord's  demand,  as Additional Rent, with interest at
the Default Rate until paid.

<PAGE>
      Section 9.4.      Alterations by Tenant.

      Tenant shall not make any alterations,  renovations, improvements or other
installations to the Premises (including, without limitation, any alterations of
the signs,  structural  alterations  or any cutting or drilling into any part of
the Premises)  unless and until: (i) Tenant shall have caused detailed plans and
specifications  therefor  to have  been  prepared  and  delivered,  at  Tenant's
expense, by a licensed architect or other duly qualified person, and (ii) Tenant
shall have obtained  Landlord's prior written approval  thereof,  which approval
shall not be  unreasonably  withheld,  conditioned  or  delayed.  If approval is
granted,  Tenant shall cause the work described in such plans and specifications
to be performed, at its expense,  promptly,  efficiently and competently by duly
qualified  or  licensed  persons  or  entities  without   interference  with  or
disruption  of the  operations  of tenants or other users and  occupants  of the
Building  or the  Project.  All such  work  shall  comply  with  all  applicable
governmental codes, rules, regulations and ordinances.

      Section 9.5.      Landlord's Right of Access.

      Landlord and its  authorized  representatives  may: (a) enter the Premises
(i) during normal  business  hours for the purpose of inspecting any repairs and
alterations  being made or required to be made by Tenant  hereunder,  or (ii) at
any  other  time  Landlord  deems  reasonably  necessary  to  prevent  waste and
deterioration of the Premises,  the Building or the Project; (b) use exclusively
all or any part of the  roof,  if any,  of the  Premises,  the  Building  or the
Project  for  any  purpose,  including,  without  limitation,  the  erecting  of
temporary  scaffolds  and other  aids to  construction  on the  exterior  of the
Premises, the Building or the Project, provided access to the Premises shall not
be denied;  (c) install,  maintain,  use, repair and replace within the Premises
pipes, ducts,  conduits,  wires, access doors and all other mechanical equipment
serving  other  parts of the  Building  or the  Project,  the same to be at such
locations  within  the  Premises  as will not  unreasonably  deny  Tenant's  use
thereof;  and (d)  make  any use it  desires  of the  side or rear  walls of the
Premises,  provided  that such use shall not  encroach  on the  interior  of the
Premises.

      Section 9.6.      Disruption in Business Operations.

      Landlord shall take all reasonable  measures to minimize disruption to and
impact on the business  operations  of Tenant with respect to any actions  taken
herein.  If,  however,  Tenant's  business  operations  within the  Premises are
materially disrupted due to any act of Landlord or any of its employees, agents,
representatives,  successors or assigns,  and such material disruption continues
for more than three (3) consecutive  business days,  Tenant's  obligation to pay
Rent  (other  than any  Additional  Rent due by reason of  Tenant's  failure  to
perform any of its other obligations  hereunder) shall be abated during any such
time.

                                   ARTICLE 10

                             INDEMNITY AND INSURANCE

      Section 10.1.     Tenant's Insurance.

      At all times from and after entry by Tenant into the  Premises  (including
for the purpose of completing  the equipping or furnishing of the Premises prior
to the commencement of occupancy),  Tenant shall take out and keep in full force
and effect, at its expense:

<PAGE>

      (a)  Commercial  general  liability   insurance  (1986  ISO  Form  or  the
equivalent)  with a combined single limit of not less than Three Million Dollars
($3,000,000.00)  per occurrence and Four Million Dollars  ($4,000,000.00) in the
General Aggregate - each location;

      (b) All-risk property  insurance  (including the perils of theft and glass
breakage)  written  at full  replacement  cost  value and with an agreed  amount
clause  endorsement  covering (i) all of Tenant's Property,  including,  without
limitation,  inventory, trade fixtures, floor coverings,  furniture,  electronic
data processing  equipment and any other property  removable by Tenant under the
provisions of this Lease, and (ii) all leasehold  improvements  installed in the
Premises by or on behalf of Tenant, regardless of the source of funding thereof;

      (c) Worker's compensation to the extent and in the amounts required by law
and including the All Other States Endorsement;

      (d)  Employer's  liability  insurance,  in an  amount  not less  than Five
Hundred Thousand Dollars ($500,000.00); and

      (e) Business  automobile  liability  insurance on all owned,  non-owned or
hired automobiles to be used by Tenant, with a combined single limit of not less
than One Million Dollars ($1,000,000.00).

      Section 10.2.     Tenant's Contractor's Insurance.  Tenant shall
require any contractor of Tenant performing work in, on or about the
Premises to take out and keep in full force and effect, at no expense to
Landlord:

      (a) Commercial general liability insurance, in an amount not less than One
Million  Dollars  ($1,000,000.00)  Endorsement,  in an amount  not less than One
Million  Dollars  ($1,000,000.00)  combined  single limit per occurrence and Two
Million Dollars ($2,000,000.00) General Aggregate each project;

      (b) Business automobile liability insurance,  with a combined single limit
of not  less  than One  Million  Dollars  ($1,000,000.00)  covering  all  owned,
non-owned or hired automobiles;

      (c)  Worker's  compensation  in  form  and  amounts  required  by law  and
including All Other States Endorsement; and

      (d) Employers liability  coverage,  including All States Endorsement in an
amount not less than Five Hundred Thousand Dollars ($500,000.00).

      Section 10.3.     Policy Requirements.

      (a) The  company  or  companies  writing  any  insurance  which  Tenant is
required  to take  out and  maintain  or cause  to be  taken  out or  maintained
pursuant to Sections 10.1 and 10.2, as well as the form of such insurance, shall
at all  times  be  subject  to  Landlord's  approval,  and any such  company  or
companies  shall be admitted to do business in the  Commonwealth of Virginia and
have a current Best rating of at least A-VII.  Commercial liability and all-risk
property insurance policies evidencing such insurance shall name Landlord and/or
its  designees  (including,  without  limitation,  any  Mortgagee) as additional
insureds,  shall be  primary  and  noncontributory,  and  shall  also  contain a
provision by which the insurer  agrees that such coverage shall not be canceled,
materially  reduced,  terminated or  non-renewed  except after thirty (30) days'

<PAGE>

advance  written  notice  to  Landlord   and/or  such  designees.   Certificates
evidencing  coverage shall be deposited with Landlord promptly upon commencement
of Tenant's  obligation to procure the same.  None of the insurance which Tenant
is required to carry shall contain deductible provisions in excess of $2,500.00,
unless  approved  in writing in advance  by  Landlord.  If Tenant  shall fail to
perform any of its obligations pursuant to this Article 10, Landlord may perform
the same and the cost thereof shall be payable upon  Landlord's  demand therefor
as  Additional  Rent,  with  interest  thereon at the Default Rate until paid in
full.

      (b) Landlord and Tenant agree that on January 1, 2001, and on January 1 of
every second (2nd) year  thereafter,  Landlord  will have the right to request a
change in the character  and/or  amounts of insurance  required to be carried by
Tenant pursuant to the provisions of this Article 10. Provided that such changes
are consistent  with insurance  required to be carried by tenants in first-class
office projects in the Washington,  D.C. - Northern  Virginia area, Tenant shall
comply with the requested  change in character  and/or amount within thirty (30)
days of Landlord's request therefor.

      Section 10.4.     Indemnities by Tenant and Landlord.

      (a) Notwithstanding any policies of insurance required of Tenant,  Tenant,
for itself and its successors and assigns, to the extent permitted by law, shall
defend,  indemnify and hold harmless Landlord and any Mortgagee against and from
all liability or claims asserted by any person against,  or incurred by Landlord
in  connection  with:  (i) the use,  occupancy or  management of the Premises by
Tenant  or any of  its  agents,  contractors,  servants,  employees,  licensees,
concessionaires, suppliers or materialmen during the Term; or (ii) any breach or
default in performing any of the obligations  under the provisions of this Lease
and/or  applicable  law by Tenant or any of its agents,  contractors,  servants,
employees,  licensees,  suppliers or  materialmen  during the Term; or (iii) any
negligent,  intentionally  tortious or other act or omission by Tenant or any of
its  agents,  contractors,  servants,  employees,  licensees,   concessionaires,
suppliers,  materialmen  or invitees  during the Term;  or (iv) any injury to or
death of any person or any damage to any property  occurring  upon the Premises,
and from and against all costs,  expenses and liabilities incurred in connection
with  any  claim,  action,  demand,  suit  at  law,  in  equity  or  before  any
administrative  tribunal,  arising  in whole or in part by  reason of any of the
foregoing (including,  by way of example rather than of limitation,  the fees of
attorneys,  investigators  and experts),  all  regardless of whether such claim,
action or proceeding is asserted  before or after the  expiration of the Term or
any earlier termination of this Lease.

      (b) If any such claim,  action or proceeding is brought  against  Landlord
and/or any Mortgagee,  Tenant shall  promptly,  if requested by Landlord or such
Mortgagee,  and at Tenant's  expense,  resist or defend  such  claim,  action or
proceeding or cause it to be resisted or defended by an insurer. Landlord shall,
at its  option,  be  entitled  to  participate  in  the  selection  of  counsel,
settlement and all other matters pertaining to such claim, action or proceeding,
all of which shall be subject,  in any case,  to the prior  written  approval of
Landlord.

      (c) Subject to the provisions of Section 10.5,  Landlord hereby agrees for
itself and its successors and assigns to indemnify and save Tenant harmless from
and against any liability or claims of liability arising solely out of the gross
negligence  or  intentional  acts and  omissions  of  Landlord,  its  agents  or
employees.

<PAGE>
      Section 10.5.     Landlord Not Responsible for Acts of Others.

      Landlord  shall  not be  responsible  or  liable  to  Tenant,  or to those
claiming  by,  through  or under  Tenant,  for any loss or  damage  which may be
occasioned  by or through the acts or  omissions  of persons  occupying or using
space  adjoining  the  Premises  or any  part  of the  premises  adjacent  to or
connecting  with the  Premises or any other part of the Building or the Project,
or for any loss or damage  resulting to Tenant (or those claiming by, through or
under Tenant) its or their property,  from the breaking,  bursting,  stoppage or
leaking of electrical cable and wires, and water,  gas, sewer or steam pipes. To
the  maximum  extent  permitted  by law,  Tenant  agrees to use and  occupy  the
Premises,  and to use such other  portions of the Building  and the Project,  as
Tenant is herein given the right to use, at Tenant's own risk.

      Section 10.6.     Landlord's Insurance.

      During  the  Term,  to  the  extent  deemed  reasonable  or  necessary  in
Landlord's  sole  discretion,  Landlord  shall  maintain  (a)  insurance  on the
Building  and the Project  against loss or damage by fire and all of the hazards
included in the extended coverage endorsement, in an amount deemed reasonable by
Landlord, (b) comprehensive liability and property damage insurance with respect
to the Common  Areas,  against  claims for personal  injury or death or property
damage  suffered  by  others  occurring  in, on or about  the  Building  and the
Project,  such public liability  insurance to afford protection in limits deemed
reasonable by Landlord,  and (c) any other  insurance,  in such form and in such
amounts as are deemed  reasonable by Landlord,  including,  without  limitation,
rent  continuation  and business  interruption  insurance,  theft  insurance and
worker's compensation, flood and earthquake, and boiler and machinery insurance.
The costs and expenses of any and all insurance  carried by Landlord pursuant to
the provisions of this Section 10.6 shall be deemed a part of Operating Costs.

      Section 10.7.     Increase in Insurance Premiums.

      Tenant  shall not do or  suffer to be done,  or keep or suffer to be kept,
anything  in,  upon or about  the  Premises  which  will  contravene  Landlord's
policies of hazard or liability  insurance or which will prevent  Landlord  from
procuring such policies from companies acceptable to Landlord. If anything done,
omitted  to be done or  suffered  by  Tenant  to be kept in,  upon or about  the
Premises  shall cause the rate of fire or other  insurance on the Premises or on
other property of Landlord or of others within the Building or the Project to be
increased  beyond the minimum rate from time to time  applicable to the Premises
or to any such other property for the use or uses made thereof, Tenant shall pay
to Landlord, as Additional Rent, the amount of any such increase upon Landlord's
demand therefor.

      Section 10.8.     Waiver of Right of Recovery.

      All policies covering real or personal property which either party obtains
affecting  the  Premises,  the Building or the Project shall include a clause or
endorsement  denying  the insurer  any rights of  subrogation  against the other
party to the extent rights have been waived by the insured before the occurrence
of injury or loss.  Notwithstanding  anything herein  contained to the contrary,
Landlord  and Tenant  waive any rights of  subrogation  or recovery  against the
other for damage or loss to their respective  property due to hazards covered or
which should be covered by policies of insurance  obtained or which should be or
have been obtained  pursuant to this Lease,  to the extent of the injury or loss
covered or which should have been covered thereby,  assuming that any deductible
shall be deemed to be insurance coverage.

<PAGE>

                                   ARTICLE 11

                                    CASUALTY

      Section 11.1.     Obligation to Repair and Reconstruct.

      If the Building shall be damaged by fire, the elements,  accident or other
casualty  (collectively,  "Casualty"),  but the  Premises  shall not  thereby be
rendered wholly or partially  untenantable,  then,  subject to the provisions of
Section 11.2, Landlord shall promptly cause such damage to be repaired and there
shall be no abatement of Rent. If as the result of Casualty,  the Premises shall
be rendered wholly or partially untenantable, then, subject to the provisions of
Section  11.2,  Landlord  shall cause such  damage to be  repaired  and all Rent
(other than any Additional Rent due Landlord by reason of Tenant's prior failure
to perform any of its obligations  hereunder) shall be abated proportionately as
to the portion of the Premises rendered  untenantable  during the period of such
untenantability.  All such repairs shall be made at the expense of Landlord, but
Landlord  shall not be required to repair any work  performed by or on behalf of
Tenant or to expend  any  amounts  in excess of the net  proceeds  of  insurance
received by  Landlord.  In  performing  its  rebuilding  obligations  hereunder,
Landlord shall have the right to make modifications to the structures comprising
the  Building,  the Project and the Premises.  Landlord  shall not be liable for
interruption  to Tenant's  business or for damage to or replacement or repair of
Tenant's Property or to any leasehold  improvements installed in the Premises by
or on behalf of Tenant,  all of which  damage,  replacement  or repair  shall be
undertaken and completed promptly by Tenant at Tenant's expense.

      Section 11.2.     Option to Terminate Lease.

      If (a) the Premises are rendered wholly untenantable,  or (b) the Premises
are  damaged  as a result  of any  cause  which  is not  covered  by  Landlord's
insurance,  or (c) the  Premises  are damaged or  destroyed  in whole or in part
during the last two (2) Lease Years of the Term,  or (d) the Building is damaged
to the extent of fifty  percent (50%) or more of its GRA, or (e) the Building is
so substantially damaged that Landlord determines,  in Landlord's sole judgment,
to demolish the Building, then and in any of such events, Landlord or Tenant may
elect to terminate this Lease by giving Tenant or Landlord,  as the case may be,
notice of such  election  within  ninety (90) days after the  occurrence of such
event. If such notice is given,  the rights and obligations of the parties shall
cease as of the date of such notice,  and Rent (other than any  Additional  Rent
due  Landlord  by reason of Tenant's  failure to perform any of its  obligations
hereunder) shall be adjusted as of the date of such termination.

      Section 11.3.     Insurance Proceeds.

      If Landlord  does not elect to  terminate  this Lease  pursuant to Section
11.2,  then,  subject  to the prior  rights  of any  Mortgagee,  Landlord  shall
disburse  and apply any net  insurance  proceeds  received  by  Landlord  to the
restoration  and rebuilding of the Building in accordance with Section 11.1. All
insurance  proceeds  payable with respect to the  Premises  (excluding  proceeds
payable  to Tenant  pursuant  to  Section  10.1),  shall  belong to and shall be
payable to Landlord.

<PAGE>

                                   ARTICLE 12

                                  CONDEMNATION

      Section 12.1.     Effect of Taking.

      If the whole or any part of the  Premises  shall be taken  pursuant to the
power of eminent domain,  whether by condemnation or deed in lieu thereof,  this
Lease  shall  terminate  as to the part so taken as of the date of such  taking.
Landlord shall make such repairs and alterations as may be necessary in order to
restore the part of the  Premises not taken to a useful  condition  and all Rent
(other than any Additional Rent due Landlord by reason of Tenant's prior failure
to  perform  any of its  obligations  hereunder)  shall be  reduced  in the same
proportion  as the  portion of the  Premises  so taken.  If any  partial  taking
renders the  remainder of the Premises  unusable for the Permitted  Use,  either
party may terminate this Lease as of the date of such taking by giving notice to
the other  party  within  thirty  (30) days  after  such  date.  Notwithstanding
anything contained herein to the contrary, if fifty percent (50%) or more of the
Premises is taken as aforesaid,  Tenant may elect to terminate  this Lease as of
the date of such taking,  by providing  written  notice of such  termination  to
Landlord  within  thirty (30) days of such date. If ten percent (10%) or more of
the Building is taken as aforesaid,  Landlord may elect to terminate  this Lease
as of the date of such taking by giving notice of such election to Tenant within
ninety (90) days after such date. If any notice of termination is given pursuant
to this Section 12.1,  this Lease and the rights and  obligations of the parties
hereunder  shall cease on the date  specified in such notice and all Rent (other
than any  Additional  Rent due Landlord by reason of Tenant's  prior  failure to
perform any of its  obligations  hereunder)  shall be adjusted as of the date of
such termination.

      Section 12.2.     Condemnation Awards.

      All compensation  awarded for any taking of the Premises or any portion of
the  Building or any interest in any of them shall belong to and be the property
of Landlord or any  Mortgagee,  and Tenant hereby assigns to Landlord all rights
with respect thereto; provided,  however, nothing contained herein shall prevent
Tenant  from  seeking in a separate  action  reimbursement  from the  condemning
authority (if permitted by law) for moving  expenses and expenses for removal of
Tenant's Property, but if and only if such action shall not reduce the amount of
the  award or  other  compensation  otherwise  recoverable  from the  condemning
authority by Landlord or any Mortgagee.

                                   ARTICLE 13

                            ASSIGNMENT AND SUBLETTING

      Section 13.1.     Landlord's Consent Required.

      (a) Except as otherwise provided  hereinbelow,  throughout the Term Tenant
shall not assign this Lease,  in whole or in part, nor sublet all or any part of
the Premises, nor otherwise permit any other Person to occupy or use any portion
of the Premises  (collectively  a  "Transfer"),  without in each instance  first
obtaining  the  written  consent  of  Landlord,   which  consent  shall  not  be
unreasonably  withheld,  conditioned  or delayed.  Landlord's  consent  shall be
deemed to be reasonably  withheld if any proposed  Transfer is to a governmental
or  quasi-governmental  entity, if the proposed  Transferee would  detrimentally
alter the  Permitted  Use of the Premises or use the Premises in a manner not in

<PAGE>

keeping  with the image of the  Project,  or if the  financial  condition of the
proposed Transferee is not reasonably  acceptable to Landlord.  This prohibition
includes any subletting or assignment  which would  otherwise occur by operation
of law or by an  assignment  or subletting to or by a receiver or trustee in any
Federal or State  bankruptcy or similar  proceeding.  Consent by Landlord to any
Transfer  shall not constitute a waiver of the  requirement  for such consent to
any subsequent assignment,  subletting,  licensing or other Transfer, or relieve
Tenant from its obligations under this Lease.

      (b) Notwithstanding  the foregoing,  Tenant shall be entitled to assign or
sublet the Premises,  in whole or in part,  without the prior written consent of
Landlord, to any Affiliate (defined below) of Tenant. Tenant shall give Landlord
written notice of any such Transfer at least thirty (30) days prior thereto.  As
used in this Section 13.1, the term "Affiliate"  means any entity which directly
or  indirectly  controls or is  controlled  by or is under  common  control with
Tenant.  For purposes of this definition,  "control"  (including the correlative
meaning of the terms "controlled by" and "under common control with") shall mean
the  possession,  directly  or  indirectly,  of the power to direct or cause the
direction of the management and policies of such an entity,  whether through the
ownership of voting stock or securities or by contract or otherwise.

      Section 13.2.     Transfer; Issuance of Corporate Shares.

      If Tenant is a  corporation  (other  than a  corporation  the  outstanding
voting stock of which is listed on an  "exchange,"  as defined in the Securities
Exchange Act of 1934),  Tenant shall give Landlord  notice  within  fifteen (15)
days  following the date upon which  additional  voting stock shall be issued by
Tenant,  or any  part  or all  of  the  corporate  shares  of  Tenant  shall  be
Transferred,  in the event that such Transfer results in a change in the present
control of Tenant or if more than fifty percent (50%) of said  corporate  shares
are  Transferred.  In the event of a Transfer  in which more than fifty  percent
(50%) of  Tenant's  voting  stock is sold to a party that is  unaffiliated  with
Tenant,  which  Transfer  shall  result  in  Tenant  vacating  the  Premises  or
undergoing a material change in the business conducted by Tenant, and whether or
not  Tenant has given such  notice,  Landlord  may  elect,  in  Landlord's  sole
discretion,  to either  terminate  this Lease at any time  thereafter by written
notice  to  Tenant  (and in the  event of any  termination,  all  Rent  shall be
adjusted  as of the date of such  termination),  or deem the  Transfer  to be an
Event or Default,  entitling  Landlord to the rights and  remedies  set forth in
Section 14.2.

      Section 13.3.     Acceptance of Rent from Transferee.

      The  acceptance  by  Landlord  of the  payment  of Rent  from  any  person
following  any Transfer  prohibited  by this Article shall not be deemed to be a
consent  by  Landlord  to such  Transfer,  nor  shall the same be deemed to be a
waiver of any right or remedy of Landlord's hereunder.

      Section 13.4.     Conditions of Consent.

      (a) If Tenant  receives  consent to a Transfer  under  Section 13.1 above,
then, in addition to any other terms and  conditions  imposed by Landlord in the
giving of such consent,  Tenant and the Transferee shall execute and deliver, on
demand,  an agreement  prepared by Landlord  which  agreement in any event shall
provide:  (i) that the Transferee shall be directly bound to Landlord to perform
all  obligations  of  Tenant  hereunder  including,   without  limitation,   the
obligation  to pay all Rent and other  amounts  provided  for herein;  (ii) that

<PAGE>

there shall be no subsequent Transfer of this Lease or of the Premises or of any
interest therein without the prior consent of Landlord  pursuant to Section 13.1
above;  (iii) that Tenant as  originally  named herein shall remain fully liable
for all  obligations  of Tenant  hereunder,  including the obligation to pay all
Rent provided  herein and including any and all  obligations  arising out of any
subsequent  amendments  to this Lease made between  Landlord and the  Transferee
(whether  or not  consented  to by  Tenant),  jointly  and  severally  with  the
Transferee; and (iv) such other provisions as Landlord shall reasonably require.

      (b) All costs  incurred  by Landlord  in  connection  with any request for
consent to a Transfer,  including costs of investigation and the reasonable fees
of Landlord's counsel,  shall be paid by Tenant on demand as a further condition
of any consent which may be given.

      Section  13.5.  Profits  from Use or Transfer.  Tenant  agrees that in the
event of a  Transfer,  Tenant  shall pay  Landlord  fifty  percent  (50%) of all
amounts received by Tenant or payable to Tenant in connection with such Transfer
in excess of Tenant's obligations  hereunder (less Tenant's actual out-of-pocket
expenses associated with such Transfer).

                                   ARTICLE 14

                                     DEFAULT

      Section 14.1.     "Event of Default" Defined.

      Any one or more of the following  events shall  constitute a default under
the terms of this Lease ("Event of Default"):

      (a) failure of Tenant to pay any Rent or other sum of money due  hereunder
to Landlord or any other  person  within ten (10)  calendar  days after  written
notice thereof from Landlord that the same is due;

      (b) sale of Tenant's interest in the Premises under attachment,  execution
or similar legal process or otherwise without Landlord's approval;

      (c)  filing  of a  petition  proposing  the  adjudication  of  Tenant as a
bankrupt or insolvent,  or the  reorganization  of Tenant,  or an arrangement by
Tenant with its creditors, whether pursuant to the Federal Bankruptcy Act or any
similar  Federal or state  proceeding,  unless such petition is filed by a party
other than Tenant and is withdrawn or dismissed within sixty (60) days after the
date of its filing;

      (d)  admission in writing by Tenant of its inability to pay its debts when
due;

      (e)  appointment  of a receiver or trustee for the business or property of
Tenant,  unless such appointment shall be vacated within thirty (30) days of its
entry;

      (f)  making by Tenant of an assignment for the benefit of its
creditors; and

      (g) default by Tenant in the  performance or observance of any covenant or
agreement of this Lease to be performed or observed by Tenant (other than as set
forth in clauses  (a)  through (f)  above),  which  default is not cured  within
thirty  (30) days after the giving of notice  thereof by  Landlord,  unless such

<PAGE>

default is of such  nature  that it cannot be cured  within said thirty (30) day
period,  in which event an Event of Default shall not be deemed to have occurred
if Tenant  institutes  a cure within such thirty (30) day period and  thereafter
diligently and continuously prosecutes the curing of same until completion,  but
in no event shall such cure period exceed ninety (90) days.

      Provided,  however, that if Tenant shall default in the performance of the
same or any similar  covenant or  agreement  two (2) or more times in any twelve
(12) month period, then  notwithstanding that such defaults have each been cured
by Tenant,  any  further  similar  defaults  shall be deemed an Event of Default
without the ability to cure.

      Section 14.2.     Remedies.

      Upon the  occurrence of an Event of Default,  Landlord,  without notice to
Tenant in any instance (except where expressly  provided for below),  may do any
one or more of the following:

      (a) Landlord may accelerate the Rent and any other charges, whether or not
stated to be Additional Rent  hereunder,  for the entire balance of the Term and
any renewal or extension  thereof,  or any part of such Rent,  and any costs and
sheriff's  or other  commissions,  whether  chargeable  to  Landlord  or Tenant,
including  watchmen's wages, as if by the terms of this Lease the balance of the
Rent and other charges were on that date payable in advance.

      (b)  Landlord may elect to  terminate  this Lease and the tenancy  created
hereby by giving  notice  to Tenant  without  any right on the part of Tenant to
save  the  forfeiture  by  payment  of any sum due or by  other  performance  of
condition or covenant  broken.  Landlord  may also elect to  terminate  Tenant's
possessory  rights and all other rights of Tenant  without  thereby  terminating
this Lease.  Landlord may, without notice,  reenter the Premises,  breaking open
locked doors, if necessary,  to effect  entrance,  for the purpose of recovering
possession  of the  Premises,  and may  proceed  to  recover  possession  of the
Premises by process of law,  any notice to quit or of  intention to re-enter the
Premises being expressly waived by Tenant. Landlord may remove Tenant and remove
all other persons and property  from the Premises,  and store such property in a
public  warehouse  or  elsewhere  at the cost of and for the  account  of Tenant
without  resort to legal  process and without  Landlord  being deemed  guilty of
trespass  or  becoming  liable  in any  way for any  loss or  damage  occasioned
thereby,  and take possession of and sell under such lien the goods and chattels
found in the Premises.

      (c) When this Lease shall be  terminated  by reason of an Event of Default
or when the Term has  expired,  any  attorney  for  Landlord  may proceed in any
competent  court for  judgment  in  ejectment  against  Tenant  and all  persons
claiming under Tenant for the recovery of possession of the Premises. If for any
reason  after such  action  shall have been  commenced,  it shall be canceled or
suspended and  possession  of the Premises  remains in or is restored to Tenant,
Landlord shall have the right upon any subsequent default or upon the expiration
or termination of this Lease to bring one or more actions to recover  possession
of the Premises.

      (d) If, in any action  for the  enforcement  of this  Lease,  Landlord  is
required to file a copy of this  Lease,  it shall not be  necessary  to file the
original,  notwithstanding  any law or practice to the  contrary.  Tenant hereby
waives all procedural  errors in any proceedings  taken by Landlord,  whether by
virtue  of the  powers  of  attorney  contained  in this  Lease or not,  and all

<PAGE>

liability  therefor.  Tenant further waives the right to any notice to remove or
any similar or successor  provision of any applicable  law, and agrees that five
(5) days' notice shall be  sufficient  in any case where a longer  period may be
statutorily specified.

      (e)  Landlord  may  perform,  on behalf and at the expense of Tenant,  any
obligation  of Tenant under this Lease which Tenant has failed to perform and of
which Landlord shall have given Tenant notice,  the cost of which performance by
Landlord,  together with  interest  thereon at the Default Rate from the date of
such expenditure, shall be deemed Additional Rent and shall be payable by Tenant
to Landlord upon demand therefor.

      (f) Landlord  may  exercise  any other legal or equitable  right or remedy
which it may have at law or in equity,  including rights of specific performance
and/or injunctive relief, where appropriate.

      Section 14.3.     Damages.

      (a) If this Lease is  terminated  by Landlord  pursuant  to Section  14.2,
Tenant  shall  remain  liable  for any  Rent  and  damages  which  may be due or
sustained  prior to such  termination  and all  reasonable  costs and  expenses,
including,   without  limitation,   sheriffs'  or  other  commissions   (whether
chargeable to Landlord or Tenant),  watchmen's  wages,  brokers' and  attorneys'
fees,  and repair and  renovation  costs  incurred by Landlord in pursuit of its
remedies  hereunder,  and/or in connection  with any  bankruptcy  proceedings of
Tenant,  and/or in  connection  with renting the Premises to others from time to
time (all such Rent, damages,  costs, fees and expenses being referred to herein
as "Termination  Damages"),  plus additional  damages for all Rent treated as in
arrears ("Liquidated  Damages") which, at the election of Landlord,  shall be an
amount equal to either:


            (i) the Rent which,  but for the  termination  of this Lease,  would
have become due during the  remainder of the Term,  less the amount of rent,  if
any,  which  Landlord  shall receive  during such period from others to whom the
Premises may be rented (other than any additional rent received by Landlord as a
result of any failure of such other person to perform any of its  obligations to
Landlord),  in which case  Liquidated  Damages  shall be computed and payable in
monthly  installments,  in  advance,  on the  first day of each  calendar  month
following the  termination  of this Lease and shall  continue  until the date on
which the Term would have  expired but for such  termination,  and any action or
suit brought to collect any such  Liquidated  Damages for any month shall not in
any manner prejudice the right of Landlord to collect any Liquidated Damages for
any subsequent months by similar preceding; or

            (ii) the present worth (as of the date of such  termination)  of the
Rent which, but for the termination of this Lease,  would have become due during
the  remainder  of the Term,  less the fair  rental  value of the  Premises,  as
determined by an  independent  real estate  appraiser  selected by Landlord,  in
which case such Liquidated  Damages shall be payable to Landlord in one lump sum
on demand and shall bear  interest  at the  Default  Rate until  paid.  "Present
worth" shall be computed by  discounting  such amount to present worth at a rate
equal to one  percentage  point  above the  discount  rate then in effect at the
Federal  Reserve  Bank.  In no event  shall  Landlord  be required to account to
Tenant for any amounts by which the fair rental  value shall have  exceeded  the
stipulated Rent at the time of such termination.

<PAGE>
      (b) If this Lease is  terminated  pursuant to Section  14.2,  Landlord may
(without so obligating itself) relet the Premises or any part thereof,  alone or
together  with other  premises,  for such term or terms (which may be greater or
less than the period which otherwise  would have  constituted the balance of the
Term) and on such terms and  conditions  (which may include  concessions or free
rent  and  alterations  of the  Premises)  as  Landlord  may  determine,  in its
commercially  reasonable  discretion,  but Landlord shall not be liable for, nor
shall Tenant's obligations  hereunder be diminished by reason of, any failure by
Landlord  to relet the  Premises  or any failure by Landlord to collect any rent
due upon such reletting.

      (c)  Notwithstanding  anything to the  contrary  set forth in this Section
14.3, in the event (i) Landlord must initiate legal action to enforce any one or
more of the provisions of this Lease against Tenant,  its successors or assigns,
or (ii) Landlord must consult with and/or engage an  attorney(s) in order (A) to
enforce any one or more of the  provisions of this Lease  against  Tenant or its
successors or assigns,  or (B) in connection  with any bankruptcy  proceeding of
Tenant,  whether  or not such  consultation  and/or  engagement  results  in the
initiation of any judicial action or termination of this Lease,  then and in any
of such events, Tenant, its successors and assigns, undertakes and agrees to pay
all costs  incurred by Landlord in connection  therewith,  including,  by way of
illustration and not of limitation, all reasonable attorneys' fees (inclusive of
consultation  fees,  research costs and  correspondence  fees),  court costs (if
awarded  post-judgment)  and any similar  professional  fees or costs associated
therewith,  which costs shall accrue  interest at the Default Rate until paid in
full.

                                   ARTICLE 15

               SUBORDINATION, ATTORNMENT AND NON-DISTURBANCE

      Section 15.1.     Subordination.

      (a) Unless a Mortgagee  shall otherwise elect as provided in Section 15.2,
Tenant's rights under this Lease are and shall remain subject and subordinate to
the  operation  and  effect  of any  mortgage,  deed of trust or other  security
instrument  constituting a lien upon the Building,  whether the same shall be in
existence  at the date hereof or created  hereafter  (any such lease,  mortgage,
deed of trust  or other  security  instrument  being  referred  to  herein  as a
"Mortgage," and the party or parties having the benefit of the same,  whether as
mortgagee,  beneficiary,  trustee or  noteholder,  being referred to hereinafter
collectively  as  a  "Mortgagee").  Tenant's  acknowledgment  and  agreement  of
subordination  as provided  for in this Section  15.1 is  self-operative  and no
further  instrument of subordination  shall be required;  however,  Tenant shall
execute,  within ten (10) days after request therefor,  such further  assurances
thereof  as shall  be  requisite  or as may be  requested  from  time to time by
Landlord  or any  Mortgagee.  Notwithstanding  the  foregoing,  Tenant  shall be
entitled to condition  its agreement to  subordinate  this Lease as aforesaid to
the  providing  to  Tenant  of  assurances  of  non-disturbance  from  any  such
Mortgagee.

      (b) Landlord hereby directs Tenant, upon (i) the occurrence of an event of
default by Landlord, as mortgagor under any Mortgage, (ii) the receipt by Tenant
of a notice of the  occurrence of such event of default under such Mortgage from
Landlord or such  Mortgagee,  and (iii) a direction by the Mortgagee  under such
Mortgage to Tenant to pay all Rent  thereafter to such  Mortgagee,  to make such
payments to such  Mortgagee,  and Landlord  agrees that in the event that Tenant
makes such payments to such Mortgagee, as aforesaid,  Tenant shall not be liable
to Landlord for the same.
<PAGE>

      Section 15.2.     Mortgagee's Unilateral Subordination.

      If a Mortgagee shall so elect by notice to Tenant or by the recording of a
unilateral  declaration  of  subordination,   this  Lease  and  Tenant's  rights
hereunder  shall be  superior  and prior in right to the  Mortgage of which such
Mortgagee  has the benefit,  with the same force and effect as if this Lease had
been  executed,  delivered  and recorded  prior to the  execution,  delivery and
recording of such Mortgage, subject,  nevertheless, to such conditions as may be
set forth in any such notice or declaration.


      Section 15.3.     Attornment and Non-disturbance.

      If any person shall succeed to all or any part of  Landlord's  interest in
the Premises,  whether by purchase,  foreclosure,  deed in lieu of  foreclosure,
power   of   sale,   termination   of   lease,   or   otherwise,   and  if  such
successor-in-interest   requests  or  requires,  Tenant  shall  attorn  to  such
successor-in-interest  and shall  execute  within  ten (10) days  after  receipt
thereof such agreement in  confirmation  of such  attornment in accordance  with
that form attached hereto as Schedule G. Failure to respond within such (10) day
period shall be deemed to be a  confirmation  by Tenant of the facts and matters
set  forth  therein.  Tenant  hereby  agrees  that  any  suit,  action  or other
proceeding  commenced  by any  Mortgagee  in order to  realize  upon  Landlord's
interest in, under and to this Lease, or any part of the Building, shall not, by
operation of law or otherwise, result in the cancellation or termination of this
Lease or of the obligations of Tenant hereunder.

                                   ARTICLE 16

                                 QUIET ENJOYMENT

      Landlord  covenants  and agrees  with  Tenant  that  Tenant  shall and may
peaceably and quietly have,  hold and enjoy the Premises for the Term, free from
any interference  whatsoever by, from or through Landlord or anyone claiming by,
from or through Landlord, except as may be otherwise provided herein.

                                   ARTICLE 17

                                     NOTICES

      Section 17.1.     Sending of Notices.

      Any notice or other communication given or required to be given under this
Lease  shall be in  writing  and shall be deemed to have been given on the third
(3rd) day  following  the day on which the same shall have been mailed by United
States registered or certified mail, return receipt  requested,  with all postal
charges  prepaid,  or given the next day if sent by national  overnight  courier
service  with  receipt  acknowledged  in writing,  in either case  addressed  to
Landlord or Tenant to the respective  notice addresses set forth in the preamble
paragraph  of this  Lease  and/or  such  other  addresses  as  either  party may
designate to the other by notice in accordance with this Section 17.1.

      Section 17.2.     Notices to Mortgagees.

      If any  Mortgagee  shall notify Tenant that it is the holder of a Mortgage
affecting the Premises,  and shall  thereby  request  copies of all notices from
Tenant, no notice, request or demand thereafter sent by Tenant to Landlord shall

<PAGE>

be  effective  unless  and until a copy of the same  shall  also be sent to such
Mortgagee in the manner  prescribed  in Section 17.1 and to such address as such
Mortgagee shall designate.

      Section 17.3.     Estoppel Certificate.

      Tenant  agrees from time to time,  upon not less than ten (10) days' prior
written request by Landlord,  to execute,  acknowledge and deliver to Landlord a
statement in writing,  in the form attached as Schedule H,  certifying that this
Lease  is  unmodified  and in full  force  and  effect  and that  Tenant  has no
defenses,  offsets or counterclaims against its obligations to pay the Base Rent
and Additional Rent and to perform its other  obligations  under this Lease, and
that there are no uncured  defaults of Landlord or Tenant under this Lease,  and
the dates  through  which all Rent has been paid,  and all such other or further
matters as are set forth  therein.  The  statement  delivered  pursuant  to this
Section 17.3 may be relied upon by any  purchaser or Mortgagee,  or  prospective
purchaser or Mortgagee, of the Building.

                                   ARTICLE 18

                                  MISCELLANEOUS

      Section 18.1.  Modification.

      It is a condition  that this Lease is subject to the  approval of Teachers
Insurance and Annuity Association of America. In addition,  if in the future and
in connection  with  obtaining  any  financing for the Building,  a lender shall
request reasonable modifications in this Lease as a condition to such financing,
Tenant will not unreasonably withhold,  delay or defer Tenant's consent thereto;
provided,  that the  modification  would not increase the  obligations of Tenant
hereunder or materially  adversely affect the leasehold  interest hereby created
or Tenant's rights granted hereunder.

      Section 18.2.     No Recordation.

      Tenant  hereby  agrees  that  Tenant  shall not  record  this Lease or any
memorandum of this Lease,  unless expressly consented to in writing by Landlord.
The  recordation  of this Lease or memorandum  hereof by Tenant in derogation of
this  Section 18.2 shall be deemed an Event of Default  hereunder,  and Landlord
shall have all of the rights and remedies set forth in Section 14.2,  including,
but not  limited to, the right to  terminate  this Lease and declare all sums of
Rent accruing under this Lease immediately due and payable. In addition,  Tenant
hereby appoints  Landlord as its  attorney-in-fact  for the purpose of executing
such  documents as may be required to nullify  and/or  release this Lease or any
memorandum hereof from the public records.



<PAGE>


      Section 18.3.     Remedies Cumulative.

      No reference to any specified right or remedy shall preclude Landlord from
exercising  any other right or from having any other remedy or from  maintaining
any action to which it may otherwise be entitled at law or in equity. No failure
by  Landlord  to insist  upon the strict  performance  of any  agreement,  term,
covenant or condition hereof, or to exercise any right or remedy consequent upon
a  breach  hereof,  and no  acceptance  of  full  or  partial  Rent  during  the
continuance  of any such breach,  shall  constitute a waiver of any such breach,
agreement,  term, covenant or condition.  No waiver by Landlord of any breach by
Tenant  under this Lease or of any  breach by any other  tenant  under any other
lease of any portion of the  Building or the Project  shall affect or alter this
Lease in any way whatsoever.

      Section 18.4.     Successors and Assigns.

      Landlord may, at any time, assign  collaterally or otherwise  transfer any
or all of its right, title and interest in the Building, or any portion thereof,
and this Lease and the covenants and conditions  herein contained shall inure to
the benefit of and be binding upon Landlord,  its  successors  and assigns,  and
shall be binding upon Tenant, its successors and assigns, and shall inure to the
benefit of Tenant  and,  subject to the  provisions  of  Article  12,  only such
assigns  of  Tenant to whom the  assignment  of this  Lease by  Tenant  has been
consented  to by  Landlord.  Upon any sale or other  transfer by Landlord of its
interest in the Premises,  Landlord shall be relieved of any  obligations  under
this Lease accruing thereafter.

      Section 18.5.     Compliance with Laws and Regulations.

      Tenant, at its expense,  shall comply with and shall cause the Premises to
comply with (a) all federal,  state,  municipal and other governmental statutes,
laws, rules, orders, regulations and ordinances (including,  without limitation,
ADA,  environmental laws, rules, orders,  regulations and ordinances)  affecting
the  Premises or any part  thereof,  or the use thereof,  including  those which
require the making of any unforeseen or  extraordinary  changes,  whether or not
any such statutes,  laws, rules, orders,  regulations or ordinances which may be
hereafter  enacted  involve a change  of policy on the part of the  governmental
body  enacting  the same,  and (b) all  rules,  orders  and  regulations  of the
National  Board  of  Fire  underwriters  or  Landlord's  fire  insurance  rating
organization or other bodies exercising similar functions in connection with the
prevention of fire or the correction of hazardous conditions, which apply to the
Premises. In addition,  Tenant shall be solely responsible for obtaining, at its
sole  cost and  expense,  all  occupational  or  business  licenses  or  permits
necessary to operate the Premises for the  Permitted  Use, and the  inability to
obtain the same shall not relieve Tenant from liability hereunder.



<PAGE>

      Section 18.6.     Captions and Headings.

      The Table of Contents  and the Article and Section  captions  and headings
are for convenience of reference only and in no way shall be used to construe or
modify the provisions set forth in this Lease.

      Section 18.7.     Joint and Several Liability.

      If two or more individuals,  corporations,  limited  liability  companies,
partnerships or other business  associations  (or any combination of two or more
thereof)  shall sign this Lease as Tenant,  the  liability  of each  individual,
corporation,   limited   liability   company,   partnership  or  other  business
association  to pay Rent and perform all other  obligations  hereunder  shall be
deemed to be joint and several,  and all notices,  payments and agreements given
or  made  by,  with or to any one of  such  individuals,  corporations,  limited
liability companies, partnerships or other business associations shall be deemed
to have been given or made by, with or to all of them. In like manner, if Tenant
shall be a partnership or other business association,  the members of which are,
by virtue of any  statute or federal  law,  subject to personal  liability,  the
liability of each such member shall be joint and several.

      Section 18.8.     Brokers' Commissions.

      Tenant represents and warrants to Landlord that it has dealt directly with
and  only  with  Spaulding  &  Slye  Colliers  ("SSC")  as  Tenant's  authorized
representative,  and Landlord, Landlord's Management Agent and Insignia (defined
below) recognize SSC as Tenant's authorized  representative.  Landlord shall pay
SSC for its  services  in  connection  with this  Lease  pursuant  to a separate
agreement.  Landlord  represents  that Landlord has dealt directly with and only
with  Insignia/ESG,  Inc.  ("Insignia")  as its authorized  representative,  and
Tenant and SSC  recognize  Insignia  as  Landlord's  authorized  representative.
Landlord  shall pay  Insignia  for its  services in  connection  with this Lease
pursuant to a separate  agreement.  Each party  further  represents to the other
that it has  dealt  with no other  broker,  finder  or other  person  who may be
entitled  to  brokerage  commissions  or  finders  fees in  connection  with the
execution of this Lease other than as specifically  set forth above.  Each party
hereby agrees to defend,  indemnify and hold harmless the other against and from
all liability  arising from any breach of such  representation  or obligation by
the indemnifying  party,  including  without  limitation the costs of reasonable
attorneys' fees in connection therewith.

      Section 18.9.     No Discrimination.

      It  is  intended  that  the  Building  shall  be  developed  so  that  all
prospective tenants thereof and all customers, employees, licensees and invitees
of all tenants  hereof  shall have the  opportunity  to obtain all of the goods,
services, accommodations,  advantages, facilities and privileges of the Building
without discrimination because of race, color, religion, sex or national origin.
To that end,  Tenant shall not  discriminate in the conduct and operation of its
business in the Premises  against any person or group of persons  because of the
race,  color,  religion,  sex or  national  origin  of such  person  or group of
persons.

      Section 18.10.    No Joint Venture.

      Any  intention  to  create a joint  venture  or  partnership  relationship
between the parties hereto is expressly disclaimed.

<PAGE>

      Section 18.11.    Conflicts; Schedules.

      If there is any conflict  between any of the Fundamental  Lease Provisions
and any other provisions of this Lease, the former shall control.  Any documents
attached hereto as Schedules,  together with all drawings and documents, if any,
prepared pursuant thereto or referred to therein, are hereby incorporated herein
and made a part hereof.

      Section 18.12.    Severability.

      If any term or provision,  or any portion  thereof,  of this Lease, or the
application  thereof to any person or  circumstances,  shall, to any extent,  be
rendered  invalid  or  unenforceable,  the  remainder  of  this  Lease,  or  the
application  of such term or  provision to persons or  circumstances  other than
those as to which it is held specifically invalid or unenforceable, shall not be
affected  thereby,  and each term and provision of this Lease shall be valid and
enforceable to the fullest extent permitted by law.

      Section 18.13.    No Third Party Beneficiary.

      Nothing  contained  in this Lease shall be  construed so as to confer upon
any other party the rights of a third party beneficiary, except rights contained
herein for the benefit of any Mortgagee.

      Section 18.14.    Corporate Tenants.

      In the event Tenant is a corporation,  the person  executing this Lease on
behalf of Tenant  hereby  covenants  and  warrants  that:  (a)  Tenant is a duly
constituted  corporation  qualified  to  do  business  in  the  Commonwealth  of
Virginia;  (b) all of Tenant's  franchise and corporate  taxes have been paid to
date;  (c) all future forms,  reports,  fees and other  documents  necessary for
Tenant to comply with applicable laws shall be filed by Tenant when due; and (d)
such persons are duly  authorized by the board of directors of such  corporation
to execute and deliver this Lease on behalf of the corporation.


      Section 18.15.    Applicable Law.

      This Lease and the rights and  obligations of the parties  hereunder shall
be construed in accordance with the laws of the  Commonwealth  of Virginia,  and
any action or proceeding arising hereunder shall be brought in the United States
District Court for the Commonwealth of Virginia or any successor court thereto.

<PAGE>

      SECTION 18.16 WAIVER OF JURY TRIAL.

      WITH  RESPECT  TO ANY  AND  ALL  ISSUES  ARISING  UNDER  OR IN ANY  MANNER
CONNECTED  WITH THE ENTRY  INTO OR  PERFORMANCE  UNDER  THIS  LEASE,  TENANT AND
LANDLORD,  ON BEHALF OF  THEMSELVES  AND THEIR  SUCCESSORS  AND ASSIGNS,  HEREBY
MUTUALLY WAIVE THE RIGHT TO REQUEST A TRIAL BY JURY, IN ANY ACTION OR PROCEEDING
BETWEEN THE PARTIES OR IN WHICH THE PARTIES  HEREBY AND OTHER  PERSONS HAVE BEEN
JOINED.

      Section 18.17     Limitation of Liability.

      Anything  contained  in any  provision  of  this  Lease  to  the  contrary
notwithstanding,  in consideration of the benefits accruing  hereunder,  Tenant,
for itself and its  successors  and  assigns,  covenants  and agrees that in the
event of any actual or alleged failure, breach or default hereunder by Landlord,
its successors or assigns:

      (a) the  sole and  exclusive  remedy  shall be  against  the  entity  then
constituting  Landlord and shall be limited to Landlord's equity interest in and
to the Building and the Project;

      (b) no partner,  officer, director or stockholder of Landlord, or partner,
trustee,  officer,  director  or  stockholder  of any entity  having a direct or
indirect financial interest in Landlord,  and no employees or agents of any such
entities, shall be sued or named as a party in any suit or action;

      (c) no service of process  shall be made  against  any  partner,  officer,
director or stockholder of Landlord, or partner,  trustee,  officer, director or
stockholder  of any entity  having a direct or  indirect  financial  interest in
Landlord;

      (d) no partner,  officer, director or stockholder of Landlord, or partner,
trustee,  officer,  director  or  stockholder  of any entity  having a direct or
indirect financial interest in Landlord,  and no employees or agents of any such
entities,  shall be  required  to answer or  otherwise  plead to any  service of
process;

      (e) no judgment shall be taken against any partner,  officer,  director or
stockholder of Landlord, or partner,  trustee,  officer, director or stockholder
of any entity  having a direct or indirect  financial  interest in Landlord,  or
against any employee or agent of any such entities;

      (f)  any  judgment  taken  against  any  partner,   officer,  director  or
stockholder of Landlord, or partner,  trustee,  officer, director or stockholder
of any entity  having a direct or indirect  financial  interest in Landlord,  or
against any employee or agent of any such entities, may be vacated and set aside
at any time nunc pro tunc;

      (g) no writ of  execution  shall ever be levied  against the assets of any
partner, officer, director or stockholder of Landlord, or any assets of Landlord
or of any  partner,  trustee,  officer,  director or  stockholder  of any entity
having a direct or  indirect  financial  interest  in  Landlord,  or against the
assets of any  trustee,  employee or agent of any such  entities,  other than as
specified in clause (a) of this Section 18.17; and

<PAGE>

      (h) Landlord  shall,  in no event, be in default in the performance of its
obligations  hereunder  unless and until  Landlord  shall have failed to perform
such  obligations  within  thirty  (30)  days,  or  such  additional  time as is
reasonably required to correct any default,  after notice to Landlord specifying
the notice of such  alleged  default.  In no event  shall  Landlord be liable to
Tenant for indirect or consequential damages.

      Section 18.18     No Accord and Satisfaction.

      The  acceptance  by Landlord  of any sums from Tenant  (whether as Rent or
otherwise)  in amounts which are less than the amounts due and payable by Tenant
hereunder is not intended,  nor shall be construed,  to constitute an accord and
satisfaction of any dispute between  Landlord and Tenant  regarding sums due and
payable by Tenant hereunder,  unless Landlord  specifically  deems it as such in
writing.

      Section 18.19     Time of Essence.

      Time is of the essence in each and every  instance  hereunder with respect
to the  covenants,  undertakings  and  conditions  to be performed  hereunder by
Tenant.

      Section 18.20     "Person(s)" Defined.

      The words "person" or "persons" as used herein,  shall mean individual(s),
corporation(s),  limited liability company(ies)  partnership(s),  firm(s), other
business  association(s),  or  governmental  entity or  entities,  whichever  is
required by the context, or all of the foregoing if the context so requires.


      Section 18.21     Consents.

      Whenever  Tenant  shall  claim  under any  provision  of this  Lease  that
Landlord  has  unreasonably  withheld,  conditioned  or delayed  its  consent or
approval to some request of Tenant,  which  consent  Landlord  has  specifically
agreed herein not to  unreasonably  withhold,  condition or delay,  Tenant shall
have no claim for damages by reason of such alleged withholding, conditioning or
delaying,  and Tenant's sole remedy  therefor shall be declaratory or injunctive
relief,  but in any event without the recovery of damages.  Unless  Landlord has
specifically agreed herein not to unreasonably withhold,  condition or delay its
consent in a given  instance,  all consents or  approvals  of Landlord  required
herein  may be  granted  or refused  in  Landlord's  sole  discretion.  Whenever
Landlord agrees in this Lease that a required  consent shall not be unreasonably
withheld,  conditioned  or delayed,  it is agreed that  Landlord  may  withhold,
condition or delay its consent if any Mortgagee shall have withheld, conditioned
or delayed any consent which may be required of it.


<PAGE>

      Section 18.23     Integration of all Prior Agreements and Execution
of Lease.

      THIS  WRITING IS INTENDED BY THE  PARTIES AS A FINAL  EXPRESSION  OF THEIR
AGREEMENT AND AS A COMPLETE AND EXCLUSIVE  STATEMENT OF THE TERMS THEREOF,  WITH
ALL NEGOTIATIONS,  CONSIDERATIONS AND REPRESENTATIONS BETWEEN THE PARTIES HAVING
BEEN  INCORPORATED  HEREIN.  NO COURSE OF PRIOR DEALINGS  BETWEEN THE PARTIES OR
THEIR OFFICERS,  EMPLOYEES, AGENTS OR AFFILIATES SHALL BE RELEVANT OR ADMISSIBLE
TO SUPPLEMENT,  EXPLAIN, OR VARY ANY OF THE TERMS OF THIS LEASE.  ACCEPTANCE OF,
OR  ACQUIESCENCE  IN, A COURSE OF  PERFORMANCE  RENDERED UNDER THIS LEASE OR ANY
PRIOR AGREEMENT BETWEEN THE PARTIES OR THEIR AFFILIATES SHALL NOT BE RELEVANT OR
ADMISSIBLE  TO  DETERMINE  THE  MEANING  OF ANY OF THE TERMS OF THIS  LEASE.  NO
REPRESENTATIONS,  UNDERSTANDINGS  OR AGREEMENTS HAVE BEEN MADE OR RELIED UPON IN
THE MAKING OF THIS LEASE OTHER THAN THOSE  SPECIFICALLY  SET FORTH  HEREIN.  ALL
PRIOR  COMMUNICATIONS FROM LANDLORD WITH RESPECT TO ESTIMATED CHARGES PAYABLE BY
TENANT  HEREUNDER  ARE FOR  INFORMATION  ONLY  AND ARE  NOT TO BE  CONSTRUED  AS
REPRESENTATIONS OF THE ACTUAL CHARGES WHICH TENANT IS REQUIRED TO PAY HEREUNDER,
OR AS BINDING UPON LANDLORD IN ANY MANNER WHATSOEVER. THIS LEASE CAN BE MODIFIED
ONLY BY A WRITING SIGNED BY EACH OF THE PARTIES HERETO.

      THE  SUBMISSION  OF THIS  LEASE  FOR  EXAMINATION  DOES NOT  CONSTITUTE  A
RESERVATION  OF OR  OPTION  FOR THE  PREMISES  OR ANY  OTHER  SPACE  WITHIN  THE
BUILDING.  THIS LEASE  SHALL  BECOME  EFFECTIVE  ONLY UPON  EXECUTION  AND LEGAL
DELIVERY THEREOF BY THE PARTIES HERETO.  THIS LEASE MAY BE EXECUTED IN MORE THAN
ONE COUNTERPART, AND EACH SUCH COUNTERPART SHALL BE DEEMED AN ORIGINAL DOCUMENT.

      If Tenant is a corporation, the authorized officers must sign on behalf of
the corporation, and by doing so such officers make the covenants and warranties
contained  in Section  18.14.  This  Lease must be  executed  for  Tenant,  if a
corporation,  by the  president or a  vice-president  and by the secretary or an
assistant  secretary,  unless  the  by-laws  or a  resolution  of the  board  of
directors  shall  provide  that other  officers are  authorized  to execute this
Lease, in which event, a certified copy of the by-laws and  resolutions  must be
furnished to Landlord.

      IN WITNESS  WHEREOF,  intending to be legally  bound  hereby,  the parties
hereto, by their duly authorized representatives, have executed this Lease as of
the day and year first above written.

ATTEST OR WITNESS:                  LANDLORD:                                  

                                    485 PROPERTIES, LLC



/s/Joseph                           By:/s/Harry St.Clair (SEAL)
                                    Name:Harry St.Clair
                                    Title:ASSISTANT SECRETARY

ATTEST OR WITNESS:                  TENANT:

                                    EXCALIBUR TECHNOLOGIES CORPORATION


/S/Nancy J. Mckinley                By:/s/James Buchanan (SEAL)
                                    Name:James Buchanan 
                                    Title:CFO

<PAGE>


                           TYSONS INTERNATIONAL PLAZA

                                  SCHEDULE A-1

                          LEGAL DESCRIPTION OF PROJECT

Part One:

      Beginning at the point of intersection of the southerly  right-of-way line
of Boone  Boulevard,  Route 786 and the  easterly  right-of-way  line of Gallows
Road,  Route 650;  thence  departing  from said line of Gallows Road and running
along and with the said line of Boone Boulevard the following two (2) courses:

      South 54(Degree)37'51" East, 543.23 feet to a point; thence

      28.24 feet along the arc of a curve  deflecting  to the right and having a
radius of 18.00 feet and a chord bearing and distance of South  09(Degree)41'06"
East, 25.43 feet to a point in the westerly  right-of-way  line of Aline Avenue,
Route 3402; thence departing from said line of Boone Boulevard and running along
and with the said line of Aline Avenue the following seven (7) courses:

      South 35(Degree)15'39" West, 163.75 feet to a point; thence

      South 43(Degree)52'28" West, 76.78 feet to a point; thence

      127.72 feet along the arc of a curve  deflecting to the right and having a
radius of 103.55 feet and a chord bearing and distance of South 70(Degree)35'47"
West, 119.78 feet to a point; thence

      94.56  feet along the arc of a curve  deflecting  to the left and having a
radius of 500.44 feet and a chord bearing and distance of North 79(Degree)28'54"
West, 94.42 feet to a point; thence,

      North 05(Degree)06'19" East, 8.50 feet to a point; thence,

      120.63 feet along the arc of a curve  deflecting  to the left and having a
radius of 508.94 feet and a chord bearing and distance of South 88(Degree)18'55"
West, 120.34 feet to a point; thence,

      49.72 feet along the arc of a curve  deflecting  to the right and having a
radius of 38.00 feet and a chord bearing and distance of North  60(Degree)59'32"
West,  46.25  feet to a point in the  aforesaid  easterly  right-of-way  line of
Gallows Road;  thence departing from said line of Aline Avenue and running along
and with the said line of Gallows Road the following three (3) courses;

      508.47 feet along the arc of a curve  deflecting to the right and having a
radius of 590.62 feet and a chord bearing and distance of North 01(Degree)09'13"
East, 492.91 feet to a point; thence,

      North 35(Degree)18'33" East, 37.35 feet to a point; thence,

      North 89(Degree)12'32" East, 34.78 feet to the point of beginning.

      Containing 210,909 square feet or 4.8418 acres.

<PAGE>

Part Two:

      Beginning at the point of intersection of the westerly  right-of-way  line
of Aline Avenue, Route 3402 and the northerly right-of-way line of Gallows Road,
Route 650; thence departing from said line of Aline Avenue and running along and
with the said line of Gallows Road the following four (4) courses:

      28.75  feet along the arc of a curve  deflecting  to the left and having a
radius of 212.00 feet and a chord bearing and distance of North 49(Degree)58'23"
West, 28.73 feet to a point; thence,

      99.67 feet along the arc of a curve  deflecting  to the right and having a
radius of 578.62 feet and a chord bearing and distance of North 48(Degree)55'25"
West, 99.55 feet to a point; thence,

      80.06 feet along the arc of a curve  deflecting  to the right and having a
radius of 33.00 feet and a chord bearing and distance of North  25(Degree)30'53"
East, 61.82 feet to a point; thence,

      North  05(Degree)01'05"  East,  8.50  feet  to a  point  in the  southerly
right-of-way  line of Relocated Aline Avenue,  Route 3402; thence departing from
said line of Gallows Road and running  along and with the said line of Relocated
Aline Avenue the following two (2) courses;

      81.04 feet along the arc of a curve  deflecting  to the right and having a
radius of 425.44 feet and a chord bearing and distance of South 79(Degree)31'30"
East, 80.91 feet to a point; thence,

      82.56  feet along the arc of a curve  deflecting  to the left and having a
radius of 178.55 feet and a chord bearing and distance of South 87(Degree)18'51"
East, 81.82 feet to a point in the aforesaid westerly right-of-way line of Aline
Avenue;  thence  departing from said line of Relocated  Aline Avenue and running
along and with the said line of Aline Avenue,

      South 35(Degree)15'39" West, 158.72 feet to the point of beginning.

      Containing 15,995 square feet or 0.3672 of an acre.


<PAGE>



Part Three:

      Beginning at a point in the southerly  right-of-way  line of Gallows Road,
Route 650,  said point also  being the north  easterly  corner of Tysons  Square
Office Condo; thence departing from Tysons Square Office Condo and running along
and with the said line of Gallows Road the following two (2) courses:

      106.24 feet along the arc of a curve  deflecting  to the left and having a
radius of 674.12 feet and a chord bearing and distance of South 13(Degree)29'50"
East, 106.13 feet to a point; thence,

      83.02 feet along the arc of a curve  deflecting  to the right and having a
radius of 56.50 feet and a chord bearing and distance of South  24(Degree)04'52"
West, 75.75 feet to a point in the northerly right-of-way line of Old Courthouse
Road,  Route 677;  thence  departing  from said line of Gallows Road and running
along  and with the  said  line of Old  Courthouse  Road the  following  two (2)
courses:

      51.85 feet along the arc of a curve  deflecting  to the right and having a
radius of 55.33 feet and a chord bearing and distance of North  86(Degree)58'42"
West, 49.98 feet to a point; thence,

      North 60(Degree)07'51" West, 52.60 feet to a point in the easterly line of
the aforesaid  Tysons Square Office Condo property;  thence  departing from said
line of Old  Courthouse  Road and running along and with the said line of Tysons
Square Office Condo,

      North 35(Degree)18'33" East, 175.88 feet to the point of beginning.

      Containing 12,175 square feet or 0.2795 of an acre.

      All three parts combined to total 239,079 square feet or 5.4885 acres.


<PAGE>


                           TYSONS INTERNATIONAL PLAZA

                                   SCHEDULE B

                               LANDLORD'S SERVICES

I.    CLEANING

A.    Office Area

Daily:      (Monday through Friday, inclusive, Saturdays, Sundays and
holidays excepted.)

      1. Empty and clean all waste  receptacles  and  ashtrays  and remove waste
material from the Premises; wash receptacles as necessary.

      2. Sweep and dust mop all uncarpeted areas using a dust-treated mop.

      3. Vacuum all rugs and carpeted areas.

      4. Hand dust and wipe clean with treated  cloths all  horizontal  surfaces
including  furniture,  office equipment,  window sills, file,  telephones within
normal reach.

      5.  Wash clean all water fountains.

      6.  Remove and dust under all desk  equipment  and  telephone  and replace
same.

      7. Wipe clean all brass and other bright work.

      8. Hand dust all grill work within normal reach.

      9.  Spot  clean  walls  around  light  switches,   door  frame  and  glass
partitions.

      10. Upon  completion of cleaning,  all lights will be turned off and doors
locked, leaving the Premises in an orderly condition.

Weekly:

      1.    Dust coat racks, and the like.

      2. Remove all finger marks from private entrance doors, light switches and
doorways.

      3.    Damp mop all hard surface floors.



<PAGE>


Quarterly:

Render high dusting not reached in daily cleaning to include:


      1. Dusting all pictures, frames, charts, graph, and similar wall hangings.

      2. Dusting all vertical  surfaces,  such as walls,  partitions,  doors and
ducts.

      3. Dusting of all pipes, ducts, and high molding.

      4.    Dusting of all venetian blinds.

B.    Lavatories

Daily:      (Monday through Friday, inclusive; Saturdays, Sundays and
holidays, excepted).

      1.    Sweep and damp mop floors.

      2. Clean all mirrors, powder shelves,  dispensers and receptacles,  bright
work, flushometers, piping, and toilet seat hinges.

      3. Wash both sides of all toilet seats.

      4.    Wash all basins, bowls and urinals.

      5. Dust and clean all powder room fixtures.

      6. Empty and clean paper towel and sanitary disposal receptacles.

      7.    Remove waste paper and refuse.

      8. Refill tissue  holders,  soap  dispensers,  towel  dispensers,  vending
sanitary dispensers; materials to be furnished by Landlord.

      9. Spot clean walls, partitions and entry doors.

      10. A sanitizing solution will be used in all lavatory cleaning.


<PAGE>


Monthly:

      1. Machine scrub lavatory floors. Reseal if needed.

      2. Wash all partitions and tile walls in lavatories.

C.    Main Lobby, Elevators, Building Exterior and Corridors

Daily:  (Monday through Friday, inclusive; Saturdays, Sundays and holidays
expected).

      1.    Sweep and wash all floors.

      2.    Vacuum all rugs and carpeted areas.

      3.    Wash all rubber mats.

      4.    Wash, clean and empty all ashtrays.

      5. Wash or vacuum floors, wipe down walls and doors.

      6. Spot clean any metal work inside lobby.

      7. Spot clean any metal work surrounding Building Entrance doors.

Monthly:  All resilient tile floors in public areas to be treated
equivalent to spray buffing.

Semi-annually:

      1. Shampoo (dry or wet as needed) all carpeting in public areas  including
walk off-mats.

      2. Strip and refinish all hard surface flooring.

D.    Window Cleaning

            Windows  of  exterior  walls  will be washed  quarterly  inside  and
outside.

E.    Other Services

      Tenant requiring services in excess of those described above shall request
same through Landlord, at Tenant's expense.



<PAGE>

II.   HEATING, VENTILATING, AIR CONDITIONING

      A. Landlord  shall,  as part of the  Operating  Expenses for the Property,
furnish  space  heating  and cooling as normal  seasonal  changes may require to
provide  reasonable  comfortable space temperature and ventilation for occupants
of the Premises under normal  business  operation,  daily from 8:00 A.M. to 6:00
P.M.,  Saturdays,  8:00 A.M. to 1:00 P.M.;  Sundays and  holidays  excepted.  No
credit  shall be given to Tenant for any  periods  during  these hours when HVAC
service is not required by Tenant.  If Tenant shall require air  conditioning or
heating or  ventilation  outside the hours and days  specified  above,  Landlord
shall furnish such service at Tenant's expense, upon at least 24 hours' notice.

      B. The air conditioning system is based upon an occupancy of not more than
one person per 150 square feet of floor area,  and upon a combined  lighting and
standard electrical load not to exceed 6.0 watts per square foot of usable area,
unless as otherwise set forth in the Lease or the Addendum.  In the event Tenant
exceeds this condition or introduces on the Premises  equipment  which overloads
the system,  and/or in any other way causes the system to not adequately perform
to their proper functions,  supplementary  systems may, at Landlord's option, be
provided by Landlord at Tenant's expense.

III.  WATER

      Cold water at  temperatures  supplied  by the City of Falls  Church  water
mains for drinking,  lavatory,  kitchen,  restaurant and toilet purposes and hot
water for lavatory  purposes  only from regular  building  supply at  prevailing
temperatures;  provided,  however,  that Landlord  may, at  Landlord's  expense,
install  a meter  or  meters  to  measure  the  water  supplied  to any  kitchen
(including  dishwashing)  and  restaurant  areas in the Premises,  in which case
Tenant shall, upon Landlord's  request,  reimburse  Landlord for the cost of the
water  (including  heating  thereof)  consumed  in such  areas and the sewer use
charges resulting therefrom.

IV.   ELEVATORS

      The  passenger  elevator  system  shall  be  in  automatic  operation  and
available  to Tenant  at all  times.  The use of the  service  elevator  will be
scheduled with the Landlord and coordinated with the needs of the other tenant.

V.    ELECTRICAL SERVICE

      Landlord shall provide  electric power for up to 1.8 watts per square foot
of usable  area for  lighting  plus 0.5 watts per square foot of usable area for
office  machines  through  standard  receptacles  for the typical  office space.
Landlord will furnish and install at Tenant's  expense all replacement  lighting
tubes,  lamps,  and ballasts  required by Tenant.  Landlord will clean  lighting
fixtures on a regularly scheduled basis at Tenant's expense.


VI.   SECURITY AND ACCESS

      Landlord  shall  provide a security  card  system at the first floor entry
lobby of both buildings and at no less than one entrance of the garage for after
hours tenant entry. Tenant shall have access to the building and garage 24 hours
per day, 365 days per year.  The cost for security entry cards shall be paid for
by Tenant.

<PAGE>




                           TYSONS INTERNATIONAL PLAZA

                                   SCHEDULE E

                        FORM OF COMMENCEMENT DATE NOTICE



      THIS  COMMENCEMENT  DATE  NOTICE  is  entered  into  this  _______  day of
____________________ 199__, by 485 PROPERTIES, LLC, a Delaware limited liability
company ("Landlord"),  and  _________________________,  a  _____________________
("Tenant"),   pursuant   to   the   provisions   of  a   certain   lease   dated
_____________________,  199__,  by and  between  Landlord  and Tenant  ("Lease")
covering   certain   space  in  the   office/retail   complex  known  as  Tysons
International  Plaza ("Building")  located in Fairfax County,  Virginia and more
particularly  described in the Lease  ("Premises").  All terms used herein shall
have the meaning assigned to such terms in the Lease.

                            W I T N E S S E T H:

      1. The  Building,  the  Premises,  the  parking  facilities  and all other
improvements  required to be constructed and furnished by Landlord in accordance
with the terms of the Lease have been  satisfactorily  completed by the Landlord
and accepted by the Tenant,  subject to the completion of "punch list" items and
the improvements described in Section 2.2 of the Lease.

      2. The Premises have been delivered to, and accepted by, the Tenant.

      3.    The Commencement Date of the Lease is the _____ day of             
___________________ 199__, and the Expiration Date is the _____ day of
----------------, -----.

      4. The total GRA of the Tenant's  Premises  consists of ________  rentable
square feet on the ____________ (_____) floor(s) of the Building, subject to the
provision of the Lease regarding determination of the rentable square footage of
the Premises.





<PAGE>



      IN WITNESS  THEREOF,  Landlord  and Tenant have  executed  and sealed this
Commencement Date Notice as of the day and year first above-written.

                                    LANDLORD:

                                    485 PROPERTIES, LLC,
                                    a Delaware limited liability company



                                       By:
                                      Name:
                                     Title:
                                     TENANT:

                                    ------------------------------,            
                                    a _____________________________



                                       By:
                                      Name:
                                     Title:





<PAGE>


                           TYSONS INTERNATIONAL PLAZA

                                   SCHEDULE F

                          CURRENT RULES AND REGULATIONS


      1. The sidewalks,  lobbies, passages, elevators and stairways shall not be
obstructed by Tenant and used by Tenant for any purposes  other than ingress and
egress  from and to Tenant's  offices.  Landlord  shall in all cases  retain the
right to control or prevent  access  thereto by any person  whose  presence,  in
Landlord's  reasonable  judgment,  would be  prejudicial  to the safety,  peace,
character or  reputation  of the Building or the Project or of any tenant of the
Project.

      2. The toilet rooms,  water closets,  sinks,  faucets,  plumbing and other
service  apparatus of any kind shall not be used by Tenant for any purpose other
than those for which  they were  installed,  and no  sweepings,  rubbish,  rags,
ashes, chemicals or other refuse or injurious substances shall be placed therein
or used in  connection  therewith  by Tenant,  or left by Tenant in the lobbies,
passages, or stairways of the Building.

      3. No skylight,  window,  door or transom of the Building shall be covered
or obstructed by Tenant,  and no window shade,  blind,  curtain,  screen,  storm
window,  awning or other  material shall be installed or placed on any window or
in any window space, except as approved in writing by Landlord.  If Landlord has
installed or hereafter  installs  any shade,  blind or curtain in the  Premises,
Tenant shall not remove it without first obtaining  Landlord's  written approval
thereto.  Tenant  shall  have the  right to  install  Building  standard  window
blinds/systems in the Premises.

      4. No sign,  lettering,  insignia,  advertisement,  notice or other  thing
shall be inscribed,  painted, installed, erected or placed in any portion of the
Premises which may be seen from outside the Building,  or on any window,  window
space or other part of the  exterior or interior of the  Building,  unless first
approved in writing by Landlord.  Names on suite  entrances shall be provided by
and only by  Landlord  in  accordance  with the  Lease,  using in each  instance
lettering of a design and in a form  consistent  with the other lettering in the
Building, and first approved in writing by Landlord. Tenant shall/will not erect
any stand,  booth or showcase or other article or matter in or upon the Premises
and/or the  Building  and/or the  Project  without  first  obtaining  Landlord's
written approval thereto.

      5.  Tenant  shall not place any  additional  lock,  security  devises,  or
graphics  upon any door or wall  within or outside  the  Premises  or  elsewhere
within the Project without Landlord's  approval,  and Tenant shall surrender all
keys for all such locks at the end of the Term.  Landlord  shall provide  Tenant
with one set of keys to the Premises when Tenant assumes possession thereof.

      6. Tenant shall not do or permit to be done  anything  which  obstructs or
interferes with the rights of any other tenant of the Project.  Tenant shall not
keep  anywhere  within the Project any matter  having an offensive  odor, or any
kerosene,  gasoline,  benzine,  camphene,  fuel or  other  explosive  or  highly
flammable material.  No bird, fish or other animal shall be brought into or kept
in or about the Premises.

<PAGE>

      7. So that the  Premises may be kept in a good state of  preservation  and
cleanliness,  Tenant shall, while in the possession of the Premises, permit only
Landlord's  employees and contractors to clean the Premises unless prior thereto
Landlord  otherwise  consents in writing.  Landlord  shall not be responsible to
Tenant for any damage done to any  furniture or other  property of Tenant or any
other person caused by any of Landlord's  employees or any other person, for any
loss sustained by any of the Tenant's employees,  or for any loss of property of
any kind in or from the Premises,  except where caused by the negligence,  gross
negligence  or willful  misconduct  of  Landlord  or those for whom  Landlord is
legally  responsible.  Tenant shall make reasonable efforts to see each day that
the  windows  are  closed  and the doors  securely  locked  before  leaving  the
Premises,  and that all lights and standard office equipment within the Premises
are turned off.

      8. If  Tenant  desires  to  install  signaling,  telegraphic,  telephonic,
protective  alarm or other  wires,  apparatus  or devices  within the  Premises,
Landlord shall approve where and how they are to be installed and,  except as so
directed, no installation,  boring or cutting shall be permitted. Landlord shall
have the right (a) to  prevent  or  interrupt  the  transmission  of  excessive,
dangerous current of electricity or otherwise into or through the Premises,  the
Building or the Project,  (b) to require the changing of wiring  connections  or
layout,  at Tenant's  expense,  to the extent that Landlord may reasonably  deem
necessary,  (c) to require compliance with such reasonable rules as Landlord may
establish  relating  thereto,  and (d) in the event of  noncompliance  with such
requirements  or rules,  immediately to cut wiring and/or to do whatever else it
considers necessary to remove the danger,  annoyance or electrical  interference
with  apparatus in any part of the Building or the Project.  Each wire installed
by the Tenant must be clearly tagged at each distributing board and junction box
and elsewhere where required by Landlord,  with the number of the office to such
wire  leads  and the  purpose  for which it is used,  together  with the name of
Tenant or other concern, if any, operating or using it.

      9. A main  lobby  directory  will be  provided  by  Landlord  on which the
Tenant's name will be placed.

      10. No  furniture  or large  equipment  may be received  in the  Building,
except  during such hours as are  designated  for such purpose by Landlord,  and
only  after  Tenant  gives  notice  thereof  to  Landlord.  Landlord  shall have
exclusive  right to prescribe  the method and manner in which any of the same is
brought  into or taken out of the  Building,  and the right to exclude  from the
Building any heavy  furniture,  safe or other  article which may create a hazard
and to require it to be located at a designated  place in the  Premises.  Tenant
shall not place any weight  anywhere  beyond the safe  carrying  capacity of the
Building.  The cost of repairing any damage to the Building or any other part of
the Project  caused by taking any of the same in or out of the Premises,  or any
damage  caused  while it is in the  Premises or the rest of the  Building or the
Project, shall be borne by Tenant as Additional Rent.

      11. Without  Landlord's prior written consent:  (a) no connection shall be
made to any  electrical  wire for  running  any fan,  motor or other  apparatus,
device or equipment,  (b) no large  machinery of any kind,  other than customary
small business machinery,  shall be allowed in the Premises, and (c) no mechanic
shall be allowed to work in areas that may affect the base  building  systems in
or about the Building,  other than one employed by Landlord,  unless approved in
writing by Landlord.


<PAGE>

      12.  Landlord shall in no event be responsible  for admitting or excluding
any person from the Premises. In case of invasion, hostile attack, insurrection,
mob violence, riot, public excitement or other commotion, explosion, fire or any
casualty,  Landlord  shall have the right to bar or limit access to the Building
to protect the safety of occupants of the  Project,  or any property  within the
Project.

      13. Landlord shall, as prescribed in the Lease, have the right to rescind,
suspend or modify the Rules and  Regulations  and to promulgate such other Rules
or  Regulations  as, in Landlord's  reasonable  judgment,  are from time to time
needed for the safety,  care,  maintenance,  operation  and  cleanliness  of the
Building and the Project,  or for the  preservation of good order therein.  Upon
Tenant's  having been given notice of the taking of any such  action,  the Rules
and Regulations as so rescinded,  suspended, modified, or promulgated shall have
the same  force and effect as if in effect at the time at which  Tenant's  Lease
was entered  into (except  that  nothing in the Rules and  Regulations  shall be
deemed in any way to alter or impair any provisions of such Lease).

      14. The use of any room  within the  Building  or the  Project as sleeping
quarters is strictly prohibited at all times.

      15.  Tenant  shall keep the windows and doors of the  Premises  (including
those  opening on  corridors  and all doors  between  rooms  entitled to receive
heating or air  conditioning  service  and rooms not  entitled  to receive  such
service),  closed while the heating or air conditioning system is operating,  in
order to minimize the energy used by, and to conserve the effectiveness of, such
system.  Tenant shall comply with all reasonable Rules and Regulations from time
to time promulgated by Landlord with respect to such system or their use.

      16. Nothing in these Rules and Regulations  shall give Tenant any right or
claim  against  Landlord or any other person if Landlord does not enforce any of
them against any other  tenant or person  (whether or not Landlord has the right
to enforce them against such tenant or person),  and no such nonenforcement with
respect to any tenant shall  constitute a waiver of the right to enforce them as
to Tenant or any other tenant or person.



<PAGE>


                           TYSONS INTERNATIONAL PLAZA

                                   SCHEDULE G

                           AGREEMENT OF SUBORDINATION
                         NON-DISTURBANCE AND ATTORNMENT


       Attached    to and made part of Lease dated ______________, 199__ Between
                   485 PROPERTIES, LLC, Landlord
                           and _______________, Tenant


      THIS AGREEMENT MADE THE ___________ day of _______________________, 199__,
by and among TEACHERS  INSURANCE AND ANNUITY  ASSOCIATION OF AMERICA, a New York
corporation,  having its principal  office and post office  address at 730 Third
Avenue,      New     York,     New     York     10017      ("Teachers")      and
____________________________________________________________ ("Tenant"),

                            W I T N E S S E T H:

      WHEREAS,  485  PROPERTIES,  LLC,  a  Delaware  limited  liability  company
("Landlord"),  is the owner in fee  simple of those  certain  premises  situate,
lying and being in Fairfax County,  Virginia, as more particularly  described in
Exhibit A attached hereto (the "Property"); and

      WHEREAS,  Teachers is the holder of and payee  under a certain  Promissory
Note dated December 29, 1989,  secured by a Deed of Trust and Security Agreement
of even date therewith,  recorded in Book 7520 at Page 723, in the Office of the
Land Records,  Fairfax County,  Virginia,  and under another certain  Promissory
Note  dated June 4, 1990,  secured  by a First  Supplement  to Deed of Trust and
Security  Agreement of even date therewith,  recorded in Book 7608 at Page 1700,
in the  Office of the Land  Records,  Fairfax  County,  Virginia  (the  "Deed of
Trust"), constituting a first lien upon the fee simple estate of Landlord;

      WHEREAS  under the  terms of a certain  lease  dated  ___________,  199__,
("Lease"),  Landlord did lease, let and demise,  subject to the Deed of Trust, a
portion of the Property as therein more particularly described ("Premises");

      WHEREAS, the parties hereto desire to establish additional rights of quiet
and peaceful possession for the benefit of Tenant under the Lease and further to
define the terms, covenants and conditions precedent for such additional rights.





<PAGE>


      NOW, THEREFORE,  in consideration of the respective demises and of the sum
of One Dollar  ($1.00) and other good and  valuable  consideration,  each to the
other in hand paid, it is hereby mutually covenanted and agreed as follows:

            1. That Teachers (in its capacity as the beneficiary  under the Deed
of Trust) does hereby represent, covenant and warrant:

            (a)  That  the  Deed  of  Trust  is in full  force  and  effect  and
unmodified.

            (b) That there is no existing  default  under the  provisions of the
Deed of Trust or in the performance of any of the terms,  covenants,  conditions
or warranties  thereof on the part of either Teachers or Landlord to be observed
and performed thereunder.

      2. That Teachers (in its capacity as beneficiary  under the Deed of Trust)
consents to and approves the Lease.

      3. That Teachers (in its capacity as beneficiary  under the Deed of Trust)
and Tenant do hereby  covenant and agree that the Deed of Trust shall be and the
same is hereby made  SUBORDINATE  to the Lease with the same force and effect as
if the Lease had been  executed,  delivered and recorded prior to the execution,
delivery and recordation of the Deed of Trust,

            EXCEPT,  HOWEVER,  that this  Subordination  shall not affect nor be
applicable to and does hereby expressly exclude:

            (a) The prior  right and claim  under and the prior lien of the Deed
of Trust in, to and upon any award or other compensation heretofore or hereafter
to be made for any taking by eminent domain of any part of the Premises,  and as
to the right of  disposition  thereof in accordance  with the  provisions of the
Deed of Trust,

            (b) The prior  right and claim  under and the prior lien of the Deed
of Trust,  in, to and upon any proceeds  payable  under all policies of fire and
rent insurance  upon the Premises and as to the right of disposition  thereof in
accordance with the terms of the Deed of Trust, and

            (c) Any  lien,  right,  power or  interest,  if any,  which may have
arisen or  intervened  in the period  between the recording of the Deed of Trust
and the execution of the Lease.

      4.  That in the  event of  foreclosure  under the Deed of Trust or sale in
lieu thereof,  or the exercise of any other rights  thereunder or under the note
which it secures or any related  documents  prior to the expiration  date of the
Lease,  including  any  extensions  and  renewals  of  the  Lease  now  provided
thereunder,  and subject to the observance  and  performance by Tenant of all of
the terms,  covenants  and  conditions  of the Lease on the part of Tenant to be
observed and performed, Teachers does hereby covenant and warrant as follows:

<PAGE>

            (a) The  quiet and  peaceful  possession  by Tenant of the  Premises
under the Lease.

            (b) That the Lease  shall  continue  in full  force and  effect  and
Teachers shall recognize the Lease and the Tenant's  rights  thereunder and will
thereby  establish direct privity of estate and contract as between Teachers and
Tenant,  with the same force and effect and with the same  relative  priority in
time and right as though the Lease were  originally  made directly from Teachers
in favor of  Tenant,  but not in  respect  of any  amendment  to such  Lease not
previously approved in writing by Teachers.

            (c) To assume such of the  obligations  on the part of the  Landlord
under  the  Lease  which  are  deemed  to run  with  the land and for so long as
Teachers shall be the owner in fee of the Premises;  provided, however, Teachers
shall not in any way or to any extent be liable to Tenant:

                  (1) For restoration of improvements following any casualty not
required to be insured  under the Lease or for the costs of any  restoration  in
excess of the  proceeds  recovered  under any  insurance  required to be carried
under the Lease;

                  (2) For any prepayment of rent or deposit,  rental security or
any other sums deposited with the original or any prior landlord under the Lease
and not delivered to Teachers; or

                  (3) For any restrictions on competition beyond the Premises.

      5. That in the event of  default  under the Deed of Trust and upon  notice
from Teachers to Tenant,  prior to the expiration  date of the Lease,  including
any extensions and renewals of the Lease now provided thereunder,  Tenant hereby
covenants and agrees to make full and complete  attornment to Teachers,  for the
balance of the term of the Lease, including any extensions and renewals thereof,
now  provided  thereunder,  upon the same terms,  covenants  and  conditions  as
therein  provided,  so as to establish  direct privity of estate and contract as
between  Teachers  and Tenant  and with the same  force and effect and  relative
priority  in time and right as though the Lease were  originally  made  directly
from  Teachers to Tenant,  and Tenant  will  thereafter  make all rent  payments
thereafter directly to Teachers.

      6. That the terms,  covenants  and  conditions  hereof  shall inure to the
benefit of and be binding upon the respective  parties hereto,  their respective
heirs, executors, administrators, successors and assigns.



<PAGE>


      IN WITNESS  WHEREOF,  the parties  hereto  have caused this  writing to be
signed,  sealed and delivered in their  respective  names and behalf,  and, if a
corporation,  by its  officers  duly  authorized,  the day and year first  above
written.

                                    Very truly yours,

                                    TEACHERS INSURANCE AND ANNUITY
                                    ASSOCIATION OF AMERICA



                                    By: _______________________________         


STATE OF _____________ )
                             )  To Wit:
COUNTY OF ___________ )

            I HEREBY CERTIFY that on this ______ day of ___________ 199_, before
me,  the  undersigned,  a  Notary  Public  of said  State,  personally  appeared
_____________________  known to me to be the person whose name is  subscribed to
the  within  instrument,  and  acknowledged  that he  executed  the same for the
purposes contained therein.

            WITNESS my hand and Notarial Seal.


                                                Notary Public

My Commission Expires:____________________


<PAGE>


                               TENANT'S AGREEMENT



      The undersigned,  as Tenant under the Lease herein described,  does hereby
accept and agree to the terms of the foregoing Subordination,  which shall inure
to the benefit of and be binding upon the undersigned and the heirs,  executors,
administrators,   legal   representatives,   successors   and   assigns  of  the
undersigned.

                                    ---------------------------------,
                                    a ________________________________



                                       By:
                                      Name:
                                     Title:



STATE OF               )
         -----------
                           )  To Wit:
COUNTY OF            )

            I HEREBY CERTIFY that on this ______ day of ___________ 199 , before
me,  the  undersigned,  a  Notary  Public  of said  State,  personally  appeared
_____________________  known to me to be the person whose name is  subscribed to
the  within  instrument,  and  acknowledged  that he  executed  the same for the
purposes contained therein.

            WITNESS my hand and Notarial Seal.



                                          Notary Public


My Commission Expires:_______________________






<PAGE>


                           TYSONS INTERNATIONAL PLAZA

                                   SCHEDULE H

                        STATEMENT OF TENANT IN RE: LEASE


Teachers Insurance and Annuity      Date:_____________                          
Association of America
730 Third Avenue
New York, NY  10017

                              Re:  Address:__________________________
                              Your Appl. No.________________________
Gentlemen:

      It is our  understanding  that you have committed to place a mortgage upon
the subject  premises and as a condition  precedent  thereof have  required this
certification by the undersigned.

      The   undersigned,   as   Lessee,   under   that   certain   lease   dated
____________________, made with 485 PROPERTIES, LLC, as Lessor, hereby certifies
that:

      1.    the undersigned has entered into occupancy of the premises
described in said lease on ________________; and

      2.    the undersigned is presently open and conducting business with     
the public in the premises; and

      3.    the base rental in the annual amount of $___________ was
payable from the date of occupancy;

      4. said  lease is in full  force  and  effect  and has not been  assigned,
modified,  supplemented  or amended in any way  (except  by  agreement(s)  dated
____________), and neither party thereto is in default thereunder; and

      5.    the same represents the entire agreement between the parties
as to this leasing; and

      6.    the Term of said lease expires on _______________; and

      7. all conditions under said lease to be performed by the Lessor have been
satisfied,   including  but  without  limitation,  all  co-tenancy  requirements
thereunder; and,

      8.    all required contributions by Lessor to Lessee on account of
Lessee's improvements have been received; and,

      9.    on this date there are no existing defenses or offsets which       
the undersigned has against the enforcement of said lease by the Lessor;
and,

<PAGE>

      10.   no rental has been paid through ___________, 19___, and no
security (or in the amount of $____________) has been deposited with the
lessor; and,

      11.   rental for ___________, 19___, has been paid.

                                Very truly yours,

                              (Tenant)_____________________________           



                              By: _________________________________
                              Name:

                              Title:




<PAGE>


                           TYSONS INTERNATIONAL PLAZA

                                   SCHEDULE I

                                      BIDS
                                   (Attached)