<PAGE>   1





                                                                   EXHIBIT 10.24





                                 FAIRFAX SQUARE


                             OFFICE LEASE AGREEMENT


                                 BY AND BETWEEN


                          FAIRFAX SQUARE ASSOCIATES II

                                   (LANDLORD)


                                      AND


                                NHP INCORPORATED

                                    (TENANT)


                             DATE: DECEMBER 8, 1995
<PAGE>   2
                                 FAIRFAX SQUARE

                             OFFICE LEASE AGREEMENT

         THIS LEASE AGREEMENT ("this Lease"), is executed in five (5)
counterparts and made as of the 8th day of December, 1995, by and between
FAIRFAX SQUARE ASSOCIATES II ("Landlord"), a Virginia general partnership, and
NHP INCORPORATED, a Delaware corporation ("Tenant"), Landlord and Tenant having
the following notice addresses on the date of this Lease:

<TABLE>
<CAPTION>
LANDLORD:                                  WITH A COPY TO:
--------                                   -------------- 
<S>                                        <C>                 
Fairfax Square Associates II               Landlord's Partner, 
8045 Leesburg Pike                         MAV Properties, Inc.
Suite 200                                  c/o Teachers Insurance and
Vienna, Virginia  22182                        Annuity Association of
Attn: Jennifer A. Tepper                       America
                                           730 Third Avenue
                                           New York, New York  10017
                                           Attn: James Fitzpatrick,
                                                 Mortgage and Real Estate     
WITH AN ADDITIONAL COPY TO:                      Law
-------------------------- 

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

TENANT:                                    WITH A COPY TO:
------                                     -------------- 

NHP Incorporated                           NHP Incorporated
Suite 601                                  Suite 601
1225 Eye Street, N.W.                      1225 Eye Street, N.W.
Washington, D.C.  20005                    Washington, D.C.  20005
Attn: Arthur Dochterman                    Attn: Joel Bonder
</TABLE>



                    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
where in this Lease provisions corresponding to Fundamental Lease provisions
appear.  The monetary charges payable by Tenant set forth in the Summary of





                                       i
<PAGE>   3
Fundamental Lease Provisions shall not be construed to constitute an exhaustive
list of all amounts which may become payable under this Lease.

<TABLE>
<S>      <C>
(a)      Main Term:                        6 years                                   (See Section 3.3)

(b)      Premises Number:                  Suite 400 (8065 Leesburg Pike)            (See Sch. A)

(c)      Gross Leasable
         Area in Premises:                 65,083 sq. ft.                            (See Section 1.2)

          (i) Gross Leasable
              Area in the
              Building:                    188,913 sq. ft.                           (See Section 1.2)
                                           (office - 124,909 sq. ft.)

         (ii) Gross Leasable
              Area in the
              Project:                     513,607.1 sq. ft.                         (See Section 1.2)

(d)       (i) Landlord's
              Architect:                   The M Group                               (See Section 2.2)

         (ii) Tenant's
              Architect                    Intraplan, Inc., and                      (See Section 2.2)
                                           Foster-Crowder Design
(e)      Engineering Plan
         Delivery Date:                    January 10, 1996                           (See Section 2.2)

(f)      Construction
         Document
         Delivery Date:                    January 10, 1996                           (See Section 2.2)

(g)      Base Rent:                                                                   (See Section 4.3)
<CAPTION>
                          Year                               Base Rent
                          ----                               ---------
                          <S>                               <C>                      
                           1                                $18.65/s.f.
                           2                                 19.12/s.f.
                           3                                 19.59/s.f.
                           4                                 23.15/s.f.
                           5                                 23.73/s.f.
                           6                                 24.33/s.f.

(h)      Security Deposit:        None

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

(j)      Scheduled Term
         Commencement Date:       March 15, 1996                    (See Section 2.4)
</TABLE>





                                       ii
<PAGE>   4
                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                          PAGE NO.
                                                                                                          --------
<S>                                                                                                         <C>                    
ARTICLE 1  INTRODUCTORY PROVISIONS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  1
                                                                                                              
         Section 1.1.     General Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  1
         Section 1.2.     Determination of GLA of Premises, Building                                          
                          and Project   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  2
         Section 1.3.     Changes to Project. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
         Section 1.4.     Status of Landlord and Project  . . . . . . . . . . . . . . . . . . . . . . . . .  3
                                                                                                              
ARTICLE 2  PREMISES AND TENANT'S WORK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
                                                                                                              
         Section 2.1.     Lease of Premises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
         Section 2.2.     Construction Plans and Contractors  . . . . . . . . . . . . . . . . . . . . . . .  5
         Section 2.3.     Construction Allowance  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
         Section 2.4.     Construction of Premises  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
         Section 2.5.     Substantial Completion and Occupancy  . . . . . . . . . . . . . . . . . . . . . . 12
         Section 2.6.     Tenant's Occupancy of Premises  . . . . . . . . . . . . . . . . . . . . . . . . . 13
         Section 2.7.     Right of First Offer (Recurring)  . . . . . . . . . . . . . . . . . . . . . . . . 14
         Section 2.8.     Right of First Offer (Secondary)  . . . . . . . . . . . . . . . . . . . . . . . . 16
         Section 2.9.     Mechanics' and other Liens  . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
         Section 2.10.    Tenant's Property; Landlord's Lien  . . . . . . . . . . . . . . . . . . . . . . . 19
                                                                                                              
ARTICLE 3  TERM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
                                                                                                              
         Section 3.1.     Term  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
         Section 3.2.     Preliminary Term  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
         Section 3.3.     "Main Term," "Lease Year" Defined . . . . . . . . . . . . . . . . . . . . . . . . 20
         Section 3.4      Renewal Term  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
         Section 3.5      Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
         Section 3.6.     Holding Over  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
                                                                                                              
ARTICLE 4  RENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
                                                                                                              
         Section 4.1.     Tenant's Agreement to Pay Rent  . . . . . . . . . . . . . . . . . . . . . . . . . 23
         Section 4.2.     Rent Commencement Date  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
         Section 4.3.     Base Rent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
         Section 4.4.     Additional Rent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
         Section 4.5.     Payment of Rent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
         Section 4.6.     Security Deposit  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
         Section 4.7.     Interest Charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
                                                                                                              
ARTICLE 5  USE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
                                                                                                              
         Section 5.1.     Prompt Occupancy and Use  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
         Section 5.2.     Operating Hours . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
         Section 5.3.     Operational Requirements  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
         Section 5.4.     Signs; Painting; Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
         Section 5.5.     Access Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
</TABLE>





                                      iii
<PAGE>   5
                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                  PAGE NO.
                                                                                  --------
<S>                                                                                  <C>                                          
ARTICLE 6  TAXES  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
                                                                                     
         Section 6.1.     Real Estate Taxes . . . . . . . . . . . . . . . . . . . . .  28
         Section 6.2.     Payment of Tenant's Taxes . . . . . . . . . . . . . . . . .  29
         Section 6.3.     Refund of Taxes . . . . . . . . . . . . . . . . . . . . . .  29
         Section 6.4.     Taxes on Rent and Other Taxes . . . . . . . . . . . . . . .  30
                                                                                     
ARTICLE 7  COMMON AREAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  30
                                                                                     
         Section 7.1.     Use and Management  . . . . . . . . . . . . . . . . . . . .  30
         Section 7.2.     Operating Costs Defined . . . . . . . . . . . . . . . . . .  31
         Section 7.3.     Tenant's Operating Costs Charge . . . . . . . . . . . . . .  35
         Section 7.4.     Parking Validation System . . . . . . . . . . . . . . . . .  38
                                                                                     
ARTICLE 8  ENVIRONMENTAL COVENANT . . . . . . . . . . . . . . . . . . . . . . . . . .  39
                                                                                     
         Section 8.1.     Environmental Covenant. . . . . . . . . . . . . . . . . . .  39
         Section 8.2.     Environmental Laws  . . . . . . . . . . . . . . . . . . . .  39
         Section 8.3.     Indemnity . . . . . . . . . . . . . . . . . . . . . . . . .  40
         Section 8.4.     Survival  . . . . . . . . . . . . . . . . . . . . . . . . .  40
                                                                                     
ARTICLE 9  MAINTENANCE, REPAIRS AND ALTERATIONS . . . . . . . . . . . . . . . . . . .  40

         Section 9.1.     Landlord's Duty to Maintain Structure and
                          Building Systems  . . . . . . . . . . . . . . . . . . . . .  40
         Section 9.2.     Tenant's Duty to Maintain Premises  . . . . . . . . . . . .  41
         Section 9.3.     Tenant's Duty to Repair Damage  . . . . . . . . . . . . . .  42
         Section 9.4.     Alterations by Tenant . . . . . . . . . . . . . . . . . . .  42
         Section 9.5.     Landlord's Right of Access  . . . . . . . . . . . . . . . .  42
                                                                                    
ARTICLE 10  INDEMNITY AND INSURANCE . . . . . . . . . . . . . . . . . . . . . . . . .  43
                                                                                    
         Section 10.1.    Tenant's Insurance  . . . . . . . . . . . . . . . . . . . .  43
         Section 10.2.    Tenant's Contractor's Insurance . . . . . . . . . . . . . .  44
         Section 10.3.    Policy Requirements . . . . . . . . . . . . . . . . . . . .  44
         Section 10.4.    Indemnities by Tenant and Landlord  . . . . . . . . . . . .  45
         Section 10.5.    Landlord Not Responsible for Acts of Others . . . . . . . .  46
         Section 10.6.    Landlord's Insurance  . . . . . . . . . . . . . . . . . . .  47
         Section 10.7.    Increase in Insurance Premiums  . . . . . . . . . . . . . .  47
         Section 10.8.    Mutual Waiver . . . . . . . . . . . . . . . . . . . . . . .  47
                                                                                    
ARTICLE 11  CASUALTY  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  48
                                                                                    
         Section 11.1.    Obligation to Repair and Reconstruct  . . . . . . . . . . .  48
         Section 11.2.    Landlord's Option to Terminate Lease  . . . . . . . . . . .  49
         Section 11.3.    Insurance Proceeds  . . . . . . . . . . . . . . . . . . . .  49
</TABLE>





                                       iv
<PAGE>   6
                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                     PAGE NO.
                                                                                     --------
<S>                                                                                    <C>
ARTICLE 12  CONDEMNATION  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  50
                                                                                    
         Section 12.1.    Effect of Taking  . . . . . . . . . . . . . . . . . . . . .  50
         Section 12.2.    Condemnation Awards . . . . . . . . . . . . . . . . . . . .  50
                                                                                    
ARTICLE 13  ASSIGNMENT AND SUBLETTING . . . . . . . . . . . . . . . . . . . . . . . .  51
                                                                                    
         Section 13.1.    Landlord's Consent Required . . . . . . . . . . . . . . . .  51
         Section 13.2.    Transfer; Issuance of Corporate Shares.   . . . . . . . . .  51
         Section 13.3.    Acceptance of Rent from Transferee  . . . . . . . . . . . .  51
         Section 13.4.    Conditions of Consent . . . . . . . . . . . . . . . . . . .  51
         Section 13.5.    Profits from Use or Transfer  . . . . . . . . . . . . . . .  52
                                                                                    
ARTICLE 14  DEFAULT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  53
                                                                                    
         Section 14.1.    "Event of Default" Defined  . . . . . . . . . . . . . . . .  53
         Section 14.2.    Remedies  . . . . . . . . . . . . . . . . . . . . . . . . .  54
         Section 14.3.    Damages . . . . . . . . . . . . . . . . . . . . . . . . . .  55
                                                                                    
ARTICLE 15  SUBORDINATION, NONDISTURBANCE AND ATTORNMENT  . . . . . . . . . . . . . .  57
                                                                                    
         Section 15.1.    Subordination . . . . . . . . . . . . . . . . . . . . . . .  57
         Section 15.2.    Mortgagee's Unilateral Subordination  . . . . . . . . . . .  58
         Section 15.3.    Attornment and Non-disturbance  . . . . . . . . . . . . . .  58
                                                                                    
ARTICLE 16  QUIET ENJOYMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  58
                                                                                    
ARTICLE 17  NOTICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  59
                                                                                    
         Section 17.1.    Sending of Notices  . . . . . . . . . . . . . . . . . . . .  59
         Section 17.2.    Notices to Mortgagees . . . . . . . . . . . . . . . . . . .  59
         Section 17.3.    Estoppel Certificate  . . . . . . . . . . . . . . . . . . .  59
                                                                                    
ARTICLE 18  MISCELLANEOUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  60
                                                                                    
         Section 18.1.    Modification  . . . . . . . . . . . . . . . . . . . . . . .  60
         Section 18.2.    Memorandum of Lease . . . . . . . . . . . . . . . . . . . .  60
         Section 18.3.    Remedies Cumulative . . . . . . . . . . . . . . . . . . . .  60
         Section 18.4.    Successors and Assigns  . . . . . . . . . . . . . . . . . .  61
         Section 18.5.    Compliance with Laws and Regulations  . . . . . . . . . . .  61
         Section 18.6.    Captions and Headings . . . . . . . . . . . . . . . . . . .  62
         Section 18.7.    Joint and Several Liability . . . . . . . . . . . . . . . .  62
         Section 18.8.    Broker's Commissions  . . . . . . . . . . . . . . . . . . .  62
         Section 18.9.    No Discrimination . . . . . . . . . . . . . . . . . . . . .  63
         Section 18.10.   No Joint Venture  . . . . . . . . . . . . . . . . . . . . .  63
         Section 18.11.   Schedules . . . . . . . . . . . . . . . . . . . . . . . . .  63
         Section 18.12.   Severability  . . . . . . . . . . . . . . . . . . . . . . .  63
</TABLE>





                                       v
<PAGE>   7
                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                    PAGE NO.
                                                                                    --------
         <S>              <C>                                                       <C>
         Section 18.13.   No Third Party Beneficiary  . . . . . . . . . . . . . . . .  64
         Section 18.14.   Corporate Tenants . . . . . . . . . . . . . . . . . . . . .  64
         Section 18.15.   Applicable Law  . . . . . . . . . . . . . . . . . . . . . .  64
         Section 18.16    Waiver of Jury Trial  . . . . . . . . . . . . . . . . . . .  64
         Section 18.17    Limitation of Liability . . . . . . . . . . . . . . . . . .  64
         Section 18.18    No Accord and Satisfaction  . . . . . . . . . . . . . . . .  67
         Section 18.19    Time of Essence . . . . . . . . . . . . . . . . . . . . . .  67
         Section 18.20    "Person(s)" Defined . . . . . . . . . . . . . . . . . . . .  67
         Section 18.21    Net Lease . . . . . . . . . . . . . . . . . . . . . . . . .  67
         Section 18.22    Consents  . . . . . . . . . . . . . . . . . . . . . . . . .  67
         Section 18.23    Unilateral Amendment  . . . . . . . . . . . . . . . . . . .  67
         Section 18.24    Integration of all Prior Agreements and
                          Execution of Lease  . . . . . . . . . . . . . . . . . . . .  68
</TABLE>





                                       vi
<PAGE>   8
                                   SCHEDULES


A                Drawing showing approximate location of the Premises

A-1              Legal Description

A-2              Tenant's Drawings

A-4              Drawing showing approximate location of the Storage Space

B                Landlord Services

C                Tenant's Plan Requirements

D                Tenant's Interior Finish Building Standards

E                Form of Term Commencement Letter

F                Rules and Regulations

G                Form of Subordination, Non-disturbance and Attornment
                 Agreement

H                Form of Tenant Estoppel

I                Base Building Description

J                Construction Schedule

K                Duties of Construction Manager

L                Prior Rights of Current Tenants





                                      vii
<PAGE>   9
                             TABLE OF DEFINED TERMS

<TABLE>
<CAPTION>
                                                                                          Defined In
Defined Term                                                                               Section 
------------                                                                              ----------
<S>                                                                                         <C>
Additional Rent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4.5
                                                                                            
Base Rent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4.3
Building  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1.1(a)
                                                                                            
Casualty  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   11.1
Common Areas  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1.1(b)
Costs Base Year . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   7.3(a)
                                                                                            
Default Rate  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1.1(c)
                                                                                            
Event of Default  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   14.1
                                                                                            
Fairfax Square .  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1.1(a)
Fiscal Year . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3.3(c)
                                                                                            
General Contractor  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2.2(c)
GLA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1.1(d)
GLA Fraction  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1.1(e)
                                                                                            
Landlord's Management Agent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1.1(f)
Lease Year  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3.3(b)
Liquidated Damages  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   15.3(a)
                                                                                            
Main Term . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3.3(a)
Market Rent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3.4(c)
Mortgage  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   15.1(a)
Mortgagee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   15.1(a)
                                                                                            
Operating Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   7.2
                                                                                            
Parking Garage  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   8.4
Partial Fiscal Year . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3.3(d)
Permitted Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   5.1
Person(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   18.20
Preliminary Term  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3.2
Premises  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1.1(d)
Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1.1(a)
                                                                                            
Recurring ROFO  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2.7(a)
Renewal Term .  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3.4(a)
Rent  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4.1
Rent Commencement Date  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4.2
Rental Tax  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   6.2
</TABLE>





                                      viii
<PAGE>   10
                      TABLE OF DEFINED TERMS (CONTINUED)

<TABLE>
<CAPTION>
                                                                                       Defined In
Defined Term                                                                            Section 
------------                                                                           ----------
<S>                                                                                         <C>
Secondary ROFO .  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2.8(a)
Security Deposit  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4.7
Storage Space. .  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2.1(b)
Substantial Completion  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2.5(a)
                                                                                            
Taxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   6.1(a)
Tax Base Year . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   6.1 (a)
Tenant's Contractors  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2.7
Tenant's Occupancy Date . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2.6
Tenant's Operating Costs Charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   7.3
Tenant's Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2.2(a)
Tenant's Plan Excess Costs  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2.2(b)
Tenant's Property . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2.10(a)
Tenant's Taxes  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   6.1(b)
Term  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3.1
Termination Damages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   14.3(a)
Transfer  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   13.1
</TABLE>





                                       ix
<PAGE>   11
                                   ARTICLE 1

                            INTRODUCTORY PROVISIONS

         Section 1.1.     General Definitions.

         As used herein, the term:

                 (a)      "Building" means the referenced tower of a
three-building multi-story office and retail towers located in Fairfax County,
Virginia.  The "Project" consists of three office/retail towers and a
multi-level parking facility, plus surface parking.  The Project is known as
"Fairfax Square," and is located at 8045, 8065 and 8075 Leesburg Pike, Vienna,
Virginia 22182.  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 (defined below) 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 Building, their officers, agents,
employees, customers, suppliers and materialmen, and those areas and facilities
used for maintenance, management and marketing of the Building, and all loading
docks, ramps and areas and access roadways thereto, delivery passages, freight
elevators, package pick-up stations, service corridors, sidewalks, walkways,
roadways, alleyways, parking areas, courts, courtyards, ramps, fountains,
retaining walls, stairways, escalators, elevators, fire corridors, fire
escapes, park areas, bus stops, bicycle parking 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 Building.

                 (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) the prime
rate charged from time to time by Citibank, New York City, plus two percent
(2%) per annum.

                 (d)      "GLA" means with respect to the area being measured,
the number of square feet of area measured in accordance with the Washington,
D.C. Association of Realtors Standard Method of Measurement (the "WDCAR"),
January 1, 1989,
<PAGE>   12
edition.  The core factor is 9.45% on a full floor user and 13.70% on a
multi-floor user, based on the WDCAR method.

The GLA in the Premises and in all other areas set aside for tenants within the
Building shall be utilized to calculate the GLA Fraction and to make any other
calculations required to determine Tenant's proportionate share of certain
charges set forth in this Lease.

                 (e)      "GLA Fraction" means a fraction, the numerator of
which shall be the GLA in the Premises and the denominator of which shall be
the total GLA in the Building.

                 (f)      "GLA Tax Fraction" means a fraction, the numerator of
which shall be the GLA in the Premises and the denominator of which shall be
the total GLA 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;
provided, however, that neither Insignia Financial Group,, Inc. nor any
affiliate thereof, shall be Landlord's Management Agent without Tenant's prior
written consent.

                 (h)      "Premises" means that portion of the Building as
shown outlined in red on Schedule A, having the GLA specified in clause (c) of
the Fundamental Lease Provisions (subject to Landlord's revised measurement
thereof as provided in Section 1.2).

         The section references 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 1.2.     Determination of GLA of Premises, Building and
Project.

                 (a)      The GLA in the Premises, the Building, and the
Project have been calculated by Landlord's architect in accordance with the
WDCAR and shall be as set forth in clause (c) of the Fundamental Lease
Provisions for all purposes of this Lease, unless adjusted pursuant to this
Section.  Landlord has delivered to Tenant a certificate from Landlord's
architect certifying (to the best of its knowledge, information and belief) the
GLA of the Premises, the Building, and the Project and shall deliver to Tenant
a similar certificate from Landlord's architect within thirty (30) days after
any increase or decrease in the size of the Premises, the Building, or the
Project for any reason.  As soon as practicable, but in any event within sixty
(60) days following Tenant's initial request therefor after





                                       2
<PAGE>   13
Tenant's Occupancy Date, Landlord shall certify to Tenant the actual GLA in the
Premises.  If the actual GLA in the Premises shall be greater or lesser than
that set forth in clause (c) of the Fundamental Lease Provisions, Landlord
shall adjust the GLA and such adjusted GLA shall thereafter be conclusively
deemed to be the GLA of the Premises for all purposes of this Lease.

                 (b)      If Tenant is dissatisfied with Landlord's
determination of the GLA of the Premises, the Building, or the Project, then
Tenant shall have the right, at Tenant's expense, to cause its architect to
determine the exact GLA contained therein.  In the event that Tenant's
architect's determination yields a GLA less than the number determined by
Landlord, Tenant's architect may submit its measurements to Landlord's
architect for review.  Whether or not the difference in the GLA falls within
the variance recognized by the WDCAR, if Landlord and Tenant are unable to
resolve the discrepancies no later than thirty (30) days after the date
Tenant's architect submitted said measurements to Landlord's architect, the
parties shall select a qualified, independent, professional third party to
resolve the discrepancies who will submit his or her determination within
fifteen (15) days after selection.  At such time as the exact GLA is
ascertained, Landlord and Tenant shall execute an amendment to this Lease
stating the exact GLA and adjusting all payments and prorations hereunder, as
necessary; provided, however, that in no event shall the GLA of the Premises be
more than 65,083 square feet.

         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.  Nothing herein contained, however, shall be deemed to
permit Landlord to change the dimensions or location of the Premises or the
lobby of the Building or materially adversely affect the access to the Premises
from the Common Areas adjacent thereto, if any, 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.

         Section 1.4.     Status of Landlord and Project.

         Landlord has good and marketable fee simple title to the Project.
Landlord is a general partnership duly organized and in good standing in the
Commonwealth of Virginia, has full right, power, and authority to execute,
deliver, and perform this Lease, and the person signing on behalf of Landlord
is authorized to do so by any and all necessary partnership and corporate
actions.





                                       3
<PAGE>   14
No litigation has been initiated or, to the knowledge of Landlord, threatened
against Landlord or against the Project which, if adversely determined, would
impair Landlord's ability to execute, deliver, and perform this Lease.  Neither
Landlord, any affiliate of Landlord, the Project, nor the Building is subject
to or otherwise bound by any legal requirements or agreement (written or oral)
which would be breached, or which would result in the creation or imposition of
any title exception applicable to the Building, by Landlord's execution,
delivery, or performance of this Lease.  Landlord will not seek or consent to
any street or alley closing or other action that would eliminate or shut off
light, air, or view to or from the Premises (provided that Landlord shall not
be required to initiate judicial action to prevent others from so doing).

                                   ARTICLE 2

                           PREMISES AND TENANT'S WORK

         Section 2.1.     Lease of Premises.

         (a)     Office 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.

         (b)     Storage Space.  Landlord hereby leases to Tenant certain
additional space containing approximately 1,000 rentable square feet in such
areas as more particularly designated on Schedule A-4 attached hereto.  In
addition, Landlord hereby grants to Tenant the right to lease certain
additional storage space in such areas of the Project as are designated for
storage by Landlord on a first-come, first-served basis (the initial storage
space and additional storage space leased to Tenant by Landlord, if any, are
collectively the "Storage Space").  Tenant may exercise its option to lease
additional Storage Space from time to time throughout the term of the Lease by
giving written notice to Landlord of its desire to lease the same, which notice
shall be conditioned upon the availability of the desired space.

         Tenant shall pay Landlord an annual rental for the Storage Space (the
"Storage Rent") equal to $10.00 per rentable square foot of GLA of the Storage
Space, adjusted annually at the rate of 2 1/2% per annum.  The Lease Years for
Storage Space shall be concurrent with the Lease Years for the Premises.  No
janitorial or trash removal services shall be provided to the Storage Space.
No other charges shall be applied, as Additional Rent or otherwise, to the
Storage Space, except for charges incurred by Landlord in enforcing its rights
relating to the Storage Space under this Lease, in accordance with the terms of
this Lease.





                                       4
<PAGE>   15
The Tenant shall have the option, exercisable at any time during the Term, to
cancel its lease of the Storage Space, upon thirty (30) days prior written
notice to the Landlord.  Except as provided in this Section 2.1(b), the terms
and conditions of Tenant's occupancy of the Storage Space shall be as set forth
in this Lease.

         The Storage Space shall be provided with non-standard double door
access, secure doors, door frames, and other improvements; provided, that the
Landlord"s cost to build out the Storage Space shall not exceed Five Dollars
($5.00) per square foot.  There shall also be no core factor for the Storage
Space (i.e., the usable areas shall be equal to the rentable area).

         (c)     Common Areas.  Tenant, its partners, employees, and invitees
shall have the right during the entire Term to use in common with others, in
accordance with the covenants and obligation of Tenant contained in this Lease,
the lobbies, entrances, exits, stairs, corridors, elevators, off-street loading
areas, men's and women's rest rooms, and other public portions or facilities
(including the health club located at the Project) from time to time provided
by Landlord for use in common by Tenant and other tenants (the "Common Areas")
located in the Building.

         Section 2.2.     Construction Plans and Contractors.

         (a)     (i) The schedule of documentation, delivery, approvals, and
construction items with respect to the build-out of the improvements to the
Premises (the "Construction Schedule") is attached to this Lease as Schedule J,
and is incorporated in this Lease by reference.

                 (ii) Tenant has delivered to Landlord and Landlord's architect
a schematic design plan ("Tenant's Plan"), showing schematic space planning,
perimeter offices and special location items.  Landlord has reviewed and
approved Tenant's Plan.

             (iii) Notwithstanding anything contained herein, Tenant, at its
sole cost and expense, may select its own architect for all architectural,
mechanical, electrical, plumbing and construction documents.  Tenant's
architect shall prepare all  necessary construction drawings and specifications
required for the construction of tenant improvements, as shown on Tenant's Plan
(the "Constructions Documents"), on or before the Construction Document
Delivery Date identified in clause (f) of the Fundamental Lease Provisions.  A
copy of the Construction Documents shall be sent to Landlord and Landlord's
architect on or before the Construction Document Delivery Date.  Landlord,
within three (3) business days of receipt of the Construction Documents, shall
either approve or reasonably disapprove the





                                       5
<PAGE>   16
same, and apprise Tenant, in writing, of Landlord's approval or disapproval.
Any disapproval shall list Landlord's specific objections or requested
revisions.

         (b)     Within five (5) business days of its receipt of the
Construction Documents, Landlord shall furnish Tenant with a statement of
anticipated costs of construction and material necessary to complete the
Premises in accordance with Tenant's Plans.  A list of tenant interior finish
building standard requirements is attached as Schedule D.  To the extent that
such costs exceed the cost of Tenant improvements and related items covered by
the Allowance (defined below), then the excess cost shall be referred to as
"Tenant Plan Excess Costs."  Tenant shall reimburse Landlord, as Additional
Rent, for Tenant Plan Excess Costs as follows:  (i) during the period of
construction, Landlord may, on or about the first day of each month, deliver to
Tenant a statement showing the proportion of Tenant Plan Excess Costs allocated
to the previous month's work, and (ii) Tenant shall pay to Landlord, as
Additional Rent, the amount specified in each statement within thirty (30) days
after its receipt thereof.  Such allocation shall be based on a fraction, the
numerator of which is the Tenant Plan Excess Cost and the denominator of which
is the total cost of the leasehold improvements to the Premises.

         (c)     (i)  Landlord shall contract with a general contractor (the
"General Contractor") to complete the leasehold improvements in accordance with
this Lease, Tenant's Plans, Schedule D and the Construction Documents.  The
Contract with the General Contractor shall provide for a ten percent (10%)
retainage until completion of the work.  Landlord shall bid the general
contractor work to at least three (3) general contractor bidders, two (2) of
whom may, at Tenant's option, be selected by Tenant.  Each of the general
contractor bidders shall submit a bid including the subcontractor or "trade"
work, bid by the general contractor to at least three (3) subcontractor
bidders.  Landlord shall deliver to Tenant a  copy of each bid within two (2)
business days after it is received.  The selection of the General Contractor
shall be by mutual agreement of the parties, each acting in commercial good
faith.

                 (ii)  Landlord or its affiliate shall be the construction
manager, and, in said capacity, shall perform the services described on
Schedule K.  For such services, Landlord shall receive a fee equal to Eighty
Cents ($.80) per square foot of GLA, which shall be paid by Tenant from the
Allowance and/or the Design Allowance.

                 (iii) Tenant shall appoint a construction coordinator who,
together with Tenant's architect, shall be entitled to field verify the
existing status of the Premises, inspect the





                                       6
<PAGE>   17
construction work and attend the periodic job-site meetings and otherwise act
on Tenant's behalf during construction.  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, and any decisions made
in the field by him shall be binding upon Tenant.

                 (iv)  Landlord agrees that it shall cooperate, and shall cause
the General Contractor and Landlord's construction manager to cooperate, with
Tenant's construction coordinator.  The fees of the General Contractor and
construction manager and Tenant's architect shall be paid out of the Allowance,
as described below.

         (d)     Landlord shall remove the existing raised floor where
designated by Tenant's architect, and restore/patch the floor to the condition
described in Schedule I, at no cost to Tenant and not out of the Allowance
(defined below).  Tenant shall have the right to use all Liebert equipment, and
all UPS units and related equipment currently located in the Premises.

         (e)     Landlord represents that the Premises is currently completed
as improved office space above base building core finished shell, which base
building is more particularly described in Schedule I.  Landlord shall maintain
all life safety systems as set forth in Schedule I, and Landlord shall comply
with all requirements of all prevailing governmental authorities having or
claiming jurisdiction over the Building, Project or Common Areas concerning the
same.  The construction coordinator and Tenant's architect shall be entitled to
field verify the completion of base building core finished shell.  If any work
is required to cause the Premises to comply with the standards for base
building finished shell and to comply with any and all requirements of all
prevailing governmental authorities having or claiming jurisdiction over the
Premises, including the requirements of the ADA (as defined below), the work
shall be completed by Landlord, at Landlord's sole cost and expense, as
promptly as possible after execution of this Lease and prior to or concurrently
with the commencement of the demolition of the existing improvements and
build-out of Tenant's improvements, at Landlord's expense.

         (f)     As used in this Lease, the Americans with Disabilities Act
("ADA") shall mean the Americans with Disabilities Act of 1990, 42 U.S.C.
Section 1201 et seq., and all implementing regulations.  Landlord and Tenant
intend to comply with the requirements of the ADA and the parties hereby
mutually agree to allocate responsibility for such compliance as follows:

                 (i)      Landlord shall have the responsibility to comply with
the requirements of the ADA in all Common Areas and common





                                       7
<PAGE>   18
elements, including all restrooms located within the Premises.  Such compliance
responsibility shall include, but shall not be limited to, the obligation to
remove architectural and communication barriers in the Common Areas and common
elements where such removal is readily achievable.  Landlord represents that
the Building is in compliance with the ADA and agrees to indemnify Tenant from
any claims arising from Building non-compliance and shall remedy the same at no
cost to Tenant, unless such non-compliance results from Tenant's actions.

             (ii)         Tenant shall have the responsibility to comply with
the requirements of the ADA in the Premises.  Such responsibility shall
include, but shall not be limited to, the obligation to remove architectural
and communication barriers in the Premises created by Tenant's trade fixtures
and leasehold improvements made by Tenant, where such removal is readily
achievable.

            (iii)         Where Building alterations involve the Common Areas
or common elements which are under Landlord's control, it shall be the
Landlord's responsibility to comply with the standards of accessibility
required under the ADA.

             (iv)         Each party shall be responsible for the ADA
compliance of its own standards, criteria, administrative methods, eligibility
criteria, policies, practices, and procedures.

             (v)          Tenant shall be responsible for the provision of any
"auxiliary aids and services," as such term is defined and used in the ADA, to
its customers, clients, or patrons if and to the extent required in connection
with the operation of its business or occupancy of the Premises.

             (vi)         To the extent permitted by the ADA, where either
Landlord or Tenant can demonstrate that barrier removal is not readily
achievable in an area in which either party has responsibility for ADA
compliance, the party responsible for compliance, as herein provided, shall
make use of alternatives to barrier removal, if such alternatives area readily
achievable.

            (vii)         Where alterations made by either party trigger "path
of travel" requirements under the ADA, the party making such alterations shall
be responsible for satisfying such requirements.

         Section 2.3.     Construction Allowance.

         (a)     Tenant shall receive a total construction allowance (the
"Allowance") in the amount of Twenty-four Dollars ($24.00) per square foot of
GLA of the Premises, which shall be applied





                                       8
<PAGE>   19
towards leasehold improvements over the existing improved condition, or as
listed below.  For the purposes of this paragraph, leasehold improvements may
specifically include, but not be limited to, construction of Tenant
improvements, construction management services, permit fees, signage costs,
suite security systems, voice and data cabling, modular furniture, Tenant's
construction coordinator, and any other applicable internal and/or external
costs incurred by Tenant (which combined costs shall not be reimbursed in an
amount in excess of the Allowance).

         (b)     In addition to the Allowance, Landlord shall pay the
following:

                 (i)      a design allowance (the "Design Allowance") not to
exceed a total of Two Dollars and Ten Cents ($2.10) per square foot of GLA of
the Premises, to offset Tenant's cost of any and all design, architectural and
engineering services and documents, including the cost of the completed
preliminary plan on 8065 Leesburg Pike and the construction management fee
described in Section 2.2(c)(ii).  The Design Allowance shall be paid by
Landlord to Tenant's architect upon Landlord's receipt of invoices, pursuant to
Landlord's payment procedure (i.e., if the invoice is submitted by the 25th day
of a month, Landlord shall pay the same by the end of the following month).
Any unused portion of the Design Allowance shall be retained by Landlord; and

                 (ii)  a relocation/moving expense (the "Moving Allowance") of
Two Dollars ($2.00) per square foot of GLA of the Premises, which shall be used
by Tenant to offset any moving expenses, which shall include all moving and
relocation expenses, costs of relocation/reconnection of computer and telephone
equipment, disassembly/reassembly of modular furniture, relocation of copier
equipment, and relocation, reassembly and parts for the central file systems.
The Moving Allowance shall be paid by Landlord to Tenant upon its reasonable
approval of Tenant's invoices for the actual costs incurred in such relocation,
pursuant to Landlord's payment procedure (i.e., if Tenant submits its invoices
by the 25th day of the month, Landlord shall reimburse Tenant by the end of the
following month).  Any unused portion of the Moving Allowance shall be retained
by Landlord.

         (c)     The cost of construction of the leasehold improvements shall
be paid monthly by the 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.  To the extent that any portion of
the Allowance to be contributed by the Landlord under this paragraph does not
apply to the initial construction of Tenant's improvements to the





                                       9
<PAGE>   20
Premises, the remaining funds shall be retained by Landlord.  It is hereby
agreed that all leasehold improvements shall immediately become the property of
Landlord upon completion unless otherwise agreed to in writing.

         Section 2.4.     Construction of Premises.

         (a)     The Landlord agrees to use due diligence to complete the
leasehold improvements including without limitation the Tenant improvements and
Base Building work as further described in Schedule C, Schedule D and Schedule
I attached hereto, and in accordance with the Schedule of Completion, on or
before March 15, 1996.  The leasehold improvements shall be completed by
Landlord in a good and workmanlike manner using new materials and in accordance
with all applicable laws and codes governing the same, including, however, not
limited to the ADA.  Upon approving Tenant's Plans, Landlord shall be required
to install all improvements set forth in Tenant's Plan; provided, however, that
Tenant's Plans shall (a) conform with all applicable laws, rules, regulations,
and ordinances; (b) conform with all Building and Project specifications and
plans; and (c) not adversely affect any Building system.  Landlord agrees that
it shall not effect change orders without the written approval of Tenant or
Tenant's construction coordinator.

         (b)     Landlord agrees that if the Premises are not substantially
complete and delivered to Tenant by March 15, 1996, then Rent shall be abated
until the Rent Commencement Date.

         (c)     (i)      If Landlord shall be hindered or delayed or prevented
from the performance of any act required in completing the leasehold
improvements to the Premises by any reason of force majeure, then the Rent
Commencement Date shall be extended for a period equivalent to the period of
delay.  "Force majeure" shall mean any delay by reasons of strikes, lockouts,
failure of power to the area to which the Project is located, restrictive
governmental laws or regulations, riots, insurrection, war, acts of God, fire
or other casualty, or other reason of as similar nature beyond the reasonable
control of Landlord or Tenant.

                 (ii)  If Landlord is unable to deliver possession of the
Premises to Tenant on the Scheduled Term Commencement Date for any reason,
based on information available to Landlord at that time, Landlord shall notify
Tenant at least fifteen (15) days prior to the Scheduled Term Commencement
Date.

         (d)     If anyof the following has not been satisfied by the date
listed below (subject in each instance except for clause (v) to any force
majeure), then Tenant shall be entitled, at Tenant's sole option, to terminate
this Lease by written notice thereof to






                                       10
<PAGE>   21





the Landlord given no later than five (5) business days after the date of such
occurrence:

                 (i) Landlord fails to deliver to Tenant a fully executed copy
of a termination agreement between Landlord and AT&T in form reasonably and
substantially similar to that approved by Tenant by the date hereof; or

                 (ii) AT&T fails to vacate the Premises by January 31, 1996; or

                 (iii) the demolition to be completed within the Premises has
not been completed by March 15, 1996; or

                 (iv) the leasehold improvements have not been Substantially
Completed by June 30, 1996; or

                 (v) notwithstanding any force majeure, the leasehold
improvements have not been Substantially Completed by September 30, 1996.

         (e)     (i)      The date by which Landlord shall use its due
diligence to deliver the Premises, Substantially Complete (the "Delivery Date,"
initially set at March 15, 1996), the date on which Tenant is entitled to
terminate the Lease for failure of the Landlord to meet the Delivery Date or
for other cause set forth in Section 2.4(d), above (each, a "Termination
Date"), and the date by which Tenant must elect to terminate, if so entitled
(the "Election Date") shall each be extended by one (1) day for each day of
Tenant Delay.  "Tenant Delay" shall mean any delay caused by or resulting from:
(1) failure of Tenant to deliver the Construction Documents to Landlord and
Landlord's architect by the Construction Document Delivery Date; (2) failure of
Tenant to timely or properly arrange its furnishings or be present for any
scheduled walk-through of the Premises in order to obtain the certificate of
occupancy once the Premises are otherwise Substantially Complete, or (3)
failure of Tenant's construction coordinator or Tenant's architect to appear at
the site within four (4) hours after request by Landlord or the General
Contractor (provided, if request is made after 2:00 p.m., or on a weekend or
legal holiday, the Tenant's construction coordinator shall respond by 12:00
p.m. noon on the next business day), and respond within two (2) business days
with a revision to the design, if necessary, upon request due to design
discrepancies.  In addition:

                 (i)      each business day of delay due to a Tenant Delay
shall add one (1) business day to the Delivery Date, the Termination Date and
the Election Date.


                                       11
<PAGE>   22
              (ii)        the dates of March 15, 1996, June 30, 1996 and
September 30, 1996, as used in paragraph (d) of this Section 2.4, shall mean
such dates, plus any days by which each is extended due to a Tenant Delay.

             (iii)        additionally, all requests for revisions and for
appearance by the Tenant's construction coordinator shall be given by facsimile
(in addition to any oral notice provided), and no Tenant Delay or force majeure
shall exist unless and until Landlord notifies Tenant of the existence of
events giving rise to the claim by Landlord of a Tenant Delay or a force
majeure, which notice shall be given by hand delivery to Tenant's construction
coordinator (with copies by facsimile to Tenant), and which notice shall be
sent within two (2) business days after the discovery of the occurrence of such
events.

         (f)   (i)        If Landlord shall be hindered or delayed or prevented
from the performance of any act required in completing the leasehold
improvements to the Premises by any reason of force majeure, then the Delivery
Date, Termination Date, Election Date and the Rent Commencement Date shall be
extended for a period equivalent to the period of delay, except for the outside
termination date set forth in clause (v) of Section 2.4(d).  "Force majeure"
shall mean any delay by reasons of strikes, lockouts, failure of power to the
area to which the Project is located, restrictive governmental laws or
regulations, riots, insurrection, war, acts of God, fire or other casualty, or
other reason of as similar nature beyond the reasonable control of Landlord or
Tenant.

              (ii)        Upon any termination of this Lease pursuant to this
Section 2.4, and except as otherwise specified herein, neither Landlord nor
Tenant shall have any continuing liability to the other beyond the payment of
Tenant's reasonable architectural fees, which shall be paid from the Allowance.

         Section 2.5.     Substantial Completion and Occupancy.

         (a)     Landlord shall give Tenant at least thirty (30) days' prior
written notice of its estimated date on which the Premises will be
substantially complete and ready for occupancy by Tenant.  The Premises shall
be deemed ready for occupancy by the Tenant on that date on which the
Landlord's architect and Tenant's construction representative have certified
that "substantial completion" of the leasehold improvements to the Premises has
occurred.  "Substantial Completion" and "Substantially Complete" mean that date
on which (i) all leasehold improvements to the Premises have been completed in
accordance with Tenant's Plans and Schedules C and D to the Lease, subject only
to minor punch-list items of work which do not substantially interfere with
Tenant and Tenant's use of the Premises, (ii) when all






                                       12
<PAGE>   23

governmental or quasi-governmental requirements applicable to the construction
and occupancy of the Premises are satisfied (it being understood that the
obligation to obtain the certificate of occupancy shall be borne mutually by
Landlord and Tenant, provided that Tenant shall timely and properly arrange its
furnishings and be available for walk-throughs of the Premises and Landlord
shall initiate and maintain the necessary contacts with Fairfax County), (iii)
Tenant, its employees, agents and invitees, have ready access to and egress
from the Premises and the Common Areas and such areas are installed, clean,
free of construction equipment and materials, (iv) all major equipment and
mechanical systems are in good working order, and (v) the Premises are broom
clean.

         (b)     Prior to the Rent Commencement Date, Tenant, Landlord, and
Tenant's architect shall inspect the Premises and the Common Areas and the
Landlord, Tenant and Tenant's architect shall prepare and execute a punch list.
Landlord shall complete as soon as conditions practically permit, but in any
event within sixty (60) days of Substantial Completion, all punch-list items,
and Tenant shall reasonably cooperate with Landlord in connection therewith.
During the first two (2) Lease Years, Landlord shall also promptly commence and
use due diligence to remediate any latent defects as they become known to
Landlord or which Tenant notifies Landlord of, after Tenant becomes aware of
the same.

         Section 2.6.     Tenant's Occupancy of Premises.

         (a)     The Tenant shall complete its move into the Premises within
forty-five (45) days following Substantial Completion.  Tenant, upon commencing
its move into the Premises, shall diligently and without interruption complete
the move; provided, however, that Tenant may complete its move in two (2)
separate phases, each of which shall be uninterrupted and continuous.  The
Monday following Tenant's move into the Premises shall be "Tenant's Occupancy
Date."  Within fifteen (15) days following Tenant's Occupancy Date, Tenant
shall deliver to Landlord a fully executed "Term Commencement Letter" in the
form attached hereto as Schedule E.

         (b)     So long as Tenant does not unreasonably interfere with the
General Contractor's construction of the leasehold improvements to the Premises
and/or any other work of Landlord within the Building, Tenant may have access
to the Premises at least thirty (30) days prior to the projected Tenant's
Occupancy Date for the purpose of installing special equipment, millwork and
similar items.  Tenant may also have access to the Project at reasonable times
upon reasonable advance notice, during construction to install cabling and
wiring to the partitions being enclosed, as necessary for the same.  Tenant
shall use due diligence to complete, or cause to be completed, the installation



                                       13
<PAGE>   24
of Tenants fixtures, furnishing and equipment prior to the date Tenant moves
into the Premises.  If any of the work or installations to be carried out by
Tenant hereunder will or are likely to interfere with the work or the schedule
being conducted or overseen by the General Contractor, Tenant shall submit to
the construction manager a description of such work and coordinate its
installations and schedule with that of the General Contractor.

         (c)     If the Premises are Substantially Complete prior to the
Scheduled Term Commencement Date, Landlord shall notify Tenant, and Tenant
shall have the option of occupying the Premises prior to the Scheduled Term
Commencement Date.  Upon Tenant's response to Landlord that it intends to
occupy the Premises, prior to the Scheduled Term Commencement Date, for its
business use: (i) the Scheduled Term Commencement Date shall be the date which
Tenant first occupies the Premises for the normal conduct of its business, as
set forth above; and (ii) Tenant shall not be obligated to pay Landlord the
Base Rent until the Scheduled Term Commencement Date.

         (d)     Landlord, at its cost and expense, shall repair or replace all
materials, workmanship, fixtures, or equipment incorporated by Landlord in the
Premises (whether as leasehold improvements or otherwise) which shall prove to
be defective during a period of twelve (12) months after the Rent Commencement
Date (the "Warranty Period").  Landlord shall assign to Tenant all warranties
(if assignable) from subcontractors and material suppliers for such materials,
workmanship, fixtures, or equipment in effect after the expiration of the
Warranty period; provided, however, that if any such warranties are not
assignable, Landlord shall, at Tenant's request, use its commercially
reasonable efforts to enforce for the benefit of Tenant, at Tenant's expense,
such non-assignable warranties.  In performing any warranty work pursuant to
this Section 2.6(d), Landlord and its contractors and subcontractors shall
endeavor to perform any significant work during non-business hours, and shall
perform all work in such manner and at such times as will cause as little
inconvenience and disruption to Tenant as is practicable under the
circumstances.

         Section 2.7.     Right of First Offer (Recurring).

         (a)     Provided that Tenant is not in default under this Lease beyond
any applicable grace, notice or cure period or is diligently pursuing a good
faith cure of any default hereunder at the time that Tenant exercises such
option, and is not subletting more than fifty percent (50%) of the Premises or
assigned its interests under the Lease, Tenant shall have an ongoing right of
first offer (the "Recurring ROFO"), subject in all respects to the prior rights
of current tenants at the Project (which rights





                                       14
<PAGE>   25
are described on Schedule L), to lease any office space not initially leased by
Tenant within Floor 2 of the Building and/or approximately 8,436 square feet of
GLA on Floor 6 of the Building, as hereinafter provided.  This Recurring ROFO
may not be offered more than two (2) times in any twelve (12) month period, and
is not contingent upon Tenant's exercise of any other right or option under
this Lease except that Tenant shall not be entitled to exercise its ROFO during
the last twelve (12) months of the Main Term unless it has exercised its
renewal option under Section 3.4.

         (b)     Landlord shall provide written notice to Tenant as early as
reasonably possible in advance of the date that any such space may become
available, and shall use its commercially reasonable efforts to provide notice
simultaneously with any notice provided to any tenants with prior rights.
Landlord's notice shall contain the rent and allowances that will apply to the
proposed ROFO space (both calculated as provided in paragraph (c) below).  If
Tenant elects to exercise its Recurring ROFO with respect to the proposed ROFO
space, it shall give written notice thereof within ten (10) business days after
receipt of Landlord's notice of availability.  If Landlord does not receive
Tenant's election to exercise its Recurring ROFO within such ten (10) business
day period, then Landlord shall be entitled to lease the proposed ROFO space to
another tenant.  If Tenant elects to exercise its Recurring ROFO, then in its
notice to Landlord of that election, Tenant shall inform Landlord as to whether
Tenant accepts or does not accept Landlord's calculation of Market Rent for the
ROFO space.  If Tenant does not accept Landlord's calculation of Market Rent,
then the parties shall proceed directly to a "three-broker" determination.
Immediately after Tenant initially rejects Landlord's determination of Market
Rent, then Landlord's broker and Tenant's broker together shall select a third
licensed real estate broker with at least five (5) years experience in the
Tysons Corner, Virginia office market.  The three brokers shall then, within
ten (10) days of Tenant's initial notice of rejection to Landlord, calculate
the Market Rent for the ROFO space by taking the average of those two (2) of
the three (3) brokers' rent calculations that are the closest together.  The
brokers' calculation of Market Rent shall be irrevocable and binding upon
Landlord and Tenant; provided, however, that Tenant's exercise of its Recurring
ROFO is conditioned upon, and shall be revocable by Tenant in its sole
discretion until, three (3) business days after the final determination (as set
forth in this Section 2.7(b)) of the Base Rent for the ROFO space.

       (c)       If Tenant exercises its Recurring ROFO, Tenant shall
thereafter enter into a lease of the proposed ROFO space on the terms and
conditions as are set forth in this Lease (except the Rent and the Allowance).
If Tenant exercises the Recurring ROFO





                                       15
<PAGE>   26
during the first two (2) Lease Years, Tenant shall pay the then-escalated Base
Rent for its occupancy of the proposed ROFO space.  If Tenant exercises the
Recurring ROFO during the remaining four (4) Lease Years, the Base Rent shall
be ninety-five percent (95%) of the then-current Market Rent (defined in the
first paragraph of Section 3.4(c)).  The Allowance applicable to the proposed
ROFO space shall be $26.10 multiplied by the GLA of the ROFO space, but reduced
on a pro-rata basis relative to Tenant's then-remaining Main Term.  Base Rent
shall commence ten (10) business days after the delivery of the ROFO space to
Tenant (the "ROFO Rent Commencement Date") with the leasehold improvements
Substantially Completed.  The leasehold improvements for the ROFO space shall
be completed by Landlord substantially in accordance with the provisions of
Article 2 of this Lease.

         (d)     Upon the ROFO Rent Commencement Date of any ROFO space, the
ROFO space shall be added to and constitute a part of the Premises, and the GLA
of the Premises shall be increased accordingly.  The term of the lease for any
ROFO space shall be coterminous with the Term of this Lease.  In addition,
Tenant shall be entitled to additional non-reserved parking spaces on the same
basis as described in Section 7.4.

         Section 2.8.     Right of First Offer (Secondary).

         (a)     Provided the Tenant is not in default under this Lease beyond
any applicable grace, notice or cure period or is diligently pursuing a good
faith cure of any default hereunder at the time that Tenant exercises such
option, and is not subletting more than fifty percent (50%) of the Premises or
assigned its interest under the Lease, Tenant shall have a one-time right of
first offer subject in all respects to the prior rights of current tenants at
the Project (which rights are described on Schedule L), to lease the entire 5th
floor of the Building (approximately 22,645 square feet of GLA), plus a
recurring right of first offer, not to exceed two times per year, on the entire
7th floor (14,537 square feet of GLA) and approximately 14,209 square feet of
GLA on the balance of the 6th floor, both spaces currently being occupied by
Informix, as the leases shall expire, but subject to the existing tenants'
renewal and expansion options (the "Secondary ROFO").  This Secondary ROFO is
not contingent upon Tenant's exercise of any other right or option under this
Lease, except the Tenant shall not be entitled to exercise its ROFO during the
last twelve (12) months of the Main Term unless it has exercised its renewal
option under Section 3.4 of this Lease.

         (b)     Landlord shall provide written notice to Tenant as early as
reasonably possible in advance of the date that any such space may become
available, and shall use its commercially reasonable efforts to provide notice
simultaneously with any





                                       16
<PAGE>   27
notice given to any tenant with prior rights.  Landlord's notice shall contain
the Rent and allowances that will apply to the proposed ROFO space (both
calculated as provided in paragraph (c), below).  If Tenant elects to exercise
its Secondary ROFO with respect to the proposed ROFO space, it shall give
written notice thereof within ten (10) business days after receipt of
Landlord's notice of availability.  If Landlord does not receive Tenant's
election to exercise its Secondary ROFO within such ten (10) business day
period, then Landlord shall be entitled to lease the proposed ROFO space to
another tenant.  If Tenant elects to exercise its Secondary ROFO, then in its
notice to Landlord of that election, Tenant shall inform Landlord as to whether
Tenant accepts or does not accept Landlord's calculation of Market Rent for the
ROFO space.  If Tenant does not accept Landlord's calculation of Market Rent,
then the parties shall proceed directly to a "three-broker" determination.
Immediately after Tenant initially rejects Landlord's determination of Market
Rent, then Landlord's broker and Tenant's broker together shall select a third
licensed real estate broker with at least five (5) years experience in the
Tysons Corner, Virginia office market.  The three brokers shall then, within
ten (10) days of Tenant's initial notice of rejection to Landlord, calculate
the Market Rent for the Premises, in accordance with the method set forth in
Section 2.7(b) above.  The brokers' calculation of Market Rent shall be
irrevocable and binding upon Landlord and Tenant; provided, however, that
Tenant's exercise of its Secondary ROFO is conditioned upon, and shall be
revocable by Tenant in its sole discretion until, three (3) business days after
the final determination (as set forth in this Section 2.8(b)) of the Base Rent
for the ROFO space.

         (c)     If Tenant exercises any one or more of its Secondary ROFOs,
Tenant shall thereafter enter into a lease of the proposed ROFO space on the
terms and conditions as are set forth in this Lease (except the Rent and the
Allowance).  If Tenant exercises a Secondary ROFO, the Base Rent shall be
ninety-five percent (95%) of the then current Market Rent (defined in the first
paragraph of Section 3.4(c)).  The Allowance applicable to the proposed ROFO
space shall be $26.10 multiplied by the GLA of the ROFO space, but shall be
reduced on a pro rata basis relative to Tenant's then remaining Main Term.
Base Rent shall commence on ten (10) business days after the delivery of the
ROFO space to Tenant with the leasehold improvements Substantially Completed.
The leasehold improvements for the ROFO space shall be completed by Landlord
substantially in accordance with the provisions of Article 2 of this Lease.

         (d)     Upon the ROFO Rent Commencement Date of any ROFO space, the
ROFO space shall be added to and constitute a part of the Premises, and the GLA
of the Premises shall be increased accordingly.  The term of the lease for any
ROFO space shall be





                                       17
<PAGE>   28

coterminous with the term of this Lease.  In addition, Tenant shall be entitled
to additional non-reserved parking spaces on the same basis as described in
Section 7.4.

         Section 2.9.     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 10.4, 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 a 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 and verification 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)     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





                                       18
<PAGE>   29
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
(defined below) of the foregoing provisions.

         (d)     To the extent permitted by law, Landlord shall have the right
to post such other notices as Landlord may reasonably deem to be appropriate
for the protection of its interests in the Premises.  The provisions of this
Section 2.9 shall apply with respect to any work performed by or on behalf of
Tenant in, on or about the Premises during the Term thereof.  Nothing contained
in this Section 2.9 shall be deemed to relieve Landlord from its responsibility
for any liens resulting from Landlord's (or its affiliate's or agent's)
performance of any construction at the Project.

         Section 2.10.    Tenant's Property; Landlord's Lien.

         (a)     All trade fixtures, furniture, equipment apparatus (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 Tenant shall repair to the reasonable 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.

         (c)     Landlord hereby waives any statutory or other lien Landlord
may have on any of Tenant's personal property located at the Premises.

                                   ARTICLE 3

                                      TERM

         Section 3.1.     Term.

         The term of this Lease ("Term") shall include the Preliminary Term and
the Main Term; provided, that if Tenant exercises its renewal option provided
in Section 3.4 of this Lease, then "Term" shall include (where the context is





                                       19
<PAGE>   30
appropriate) the Preliminary Term, the Main Term and the Renewal 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 Rent Commencement Date.

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

         (a)     "Main Term" means the period commencing on the Rent
Commencement Date and, subject to the provisions of Article 15 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 first (1st) day of the calendar month immediately
following the calendar month containing the Rent Commencement Date, as defined
in Section 4.2, unless the Rent Commencement Date shall be the first (1st) day
of the calendar month, in which event the Lease Year shall commence on the Rent
Commencement Date.

         (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      Renewal Term.

         (a)     Tenant shall have and is hereby granted one (1) option to
extend the Main Term, for an additional five (5) year term (the "Renewal
Term"), commencing at the expiration of the Main Term and terminating on the
fifth (5th) anniversary of the expiration of the Main Term.  At least nine (9)
months before the expiration of the Main Term, Tenant shall provide written
notice to the Landlord of its desire to renew the Lease; provided, that the
renewal option shall be exercisable only if the Tenant (i) is not in default
under the Lease beyond any applicable grace, notice or cure period or is
diligently pursuing a good faith cure of any outstanding default, and (ii) has
not sublet more than fifty percent (50%) of the Premises or assigned its
interests under the Lease.

         (b)     Except as provided as follows, the Renewal Term shall be upon
the same terms, covenants and conditions as are set forth





                                       20
<PAGE>   31
in this Lease, except for the provision of parking at no cost to Tenant (which
parking during any Renewal Term shall be at a rate not higher than the most
favorable rate [which may be zero] being given at that time to any office
tenant within the Project).  For the purposes of this Lease, no distinction is
made between the terms "extend" or "renew" or any variations thereof.

         (c)     The Base Rent for the first (1st) Lease Year of the Renewal
Term shall be ninety-five percent (95%) of Market Rent.

         "Market Rent" means the annual fair market rental for comparable
office premises in comparable buildings for a comparable term that would be
agreed upon by a landlord and a tenant located in the Tysons Corner, Virginia
area, taking into consideration the following: (a) the landlord and tenant are
well informed and well advised and each is acting in what it considers its own
best interests; (b) Landlord will not be providing to Tenant any market
concessions, including without limitation rental abatement, tenant improvement
allowance and additional tenant concessions, if any, being offered at
comparable buildings (which would serve to reduce what would otherwise be the
Market Rent); (c) the Premises are to be let substantially subject to the
provisions of this Lease for a five (5) year term; and (d) there is no broker's
or finder's fee or commission payable by either party, unless Tenant has
retained a broker, in which case Landlord shall pay Tenant's broker a market
rate commission or less if applicable, and the fact that Landlord is paying
such a commission shall be taken into account in determining Market Rent; and
(e) the Premises are being demised in their then "as-is" condition.  Any
determination of Market Rent shall also include the rent escalation applicable
during the Renewal Term.

         Within thirty (30) days of its receipt of Tenant's notice of its
desire to exercise a renewal option, the Landlord shall send to the Tenant a
written notice specifying its good faith determination of the Market Rent,
including rent escalations, for the Premises.  In its determination of Market
Rent, Landlord shall provide its estimate, in its commercial good faith, of the
Operating Costs and Taxes.  The Base Years for Building Operating Costs and for
Taxes shall also be updated to the twelve (12) month period following the
commencement date of the Renewal Term.  Within thirty (30) days of its receipt
of notice from Landlord, Tenant shall accept or challenge, in writing,
Landlord's determination of Market Rent.  If Tenant challenges Landlord's
determination of Market Rent, (i) the parties shall attempt to negotiate
mutually acceptable renewal terms, or Tenant may elect to proceed directly to a
"three-broker" determination and (ii) Tenant shall have the right to rescind
its exercise of said renewal option within five (5) business days following the
final determination of Market Rent.  If Landlord and Tenant are unable to agree
on Market Rent within ten (10) days after Tenant





                                       21
<PAGE>   32
initially rejects Landlord's determination of Market Rent, then Landlord and
Tenant shall each, within ten (10) days thereafter, select a licensed real
estate broker with at least five (5) years experience in the Tysons Corner,
Virginia area office market, who shall each determine the Market Rent for the
Premises in accordance with this paragraph.

         If the higher determination of the Market Rent submitted by one of the
brokers is equal to or less than one hundred ten percent (110%) of the
determination of the Market Rent submitted by the other broker, the Market Rent
shall be the average of the two determinations.  If the determination of the
Market Rent submitted by one of the brokers exceeds one hundred ten percent
(110%) of the determination of the Market Rent submitted by the other broker,
the two brokers shall jointly, within five (5) days after notice from either
Landlord or Tenant, appoint a third broker with similar qualifications to
determine the Market Rent.  If the two brokers cannot agree as to the selection
of a third broker within five (5) days after the request that they do so,
either party may request that any officer of the Board of Realtors for Fairfax
County appoint the third broker, which appointment shall be made within ten
(10) days thereafter.  The third broker shall complete its determination of the
Market Rent within thirty (30) days after its appointment.  The Market Rent
shall be that determination which provides for a net effective rental rate that
is neither highest or lowest of the three determinations, unless two
determinations are the same, in which event it shall be that amount.

         Landlord and Tenant shall each bear the cost of their respective
brokers, and one-half (1/2) the cost of the third broker, if any.

         Section 3.5      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
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 six (6) months
prior to the expiration of the Term, upon reasonable prior notice to Tenant,
Landlord shall have the right to show the Premises and all parts thereof to
prospective tenants during normal business hours.





                                       22
<PAGE>   33
         Section 3.6.     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 or Tenant on thirty (30) days' prior written notice, at a monthly
rental equal to one hundred fifty percent (150%) of the sum of (i) the monthly
installment of Base Rent payable during the last calendar month of the Term and
(ii) one twelfth (1/12) of the average annual Operating Charge, Tenant's
Utility Charge and Tenant's Taxes payable thereunder for the last two (2) Lease
Years.  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; provided, however, that Tenant may assert all applicable defenses in
any such proceeding.

                                   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 accrued and payable during the Term shall survive the termination of this
Lease.

         Section 4.2.     Rent Commencement Date.  "Rent Commencement Date"
means the date that is ten (10) business days following the Substantial
Completion of the leasehold improvements.

         Section 4.3.     Base Rent.  Tenant shall pay Landlord the Base Rent
set forth in clause (g) of the Fundamental Lease Provisions, in twelve (12)
equal monthly installments, on the first (1st) day of each calendar month.  If
the Main Term should begin on a date other than the first (1st) day of a
calendar month, Tenant shall pay Landlord as Base Rent for such days remaining
in the partial month the product obtained by multiplying 1/365th of the Base
Rent for the first Lease Year by the number of days remaining in such partial
month.

         Section 4.4.     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





                                       23
<PAGE>   34
to Landlord pursuant to this Lease (collectively, "Additional Rent"), whether
or not the same are designated as Additional Rent.

         Section 4.5.     Payment of Rent.

         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 five (5) days after notice that the same is due, Tenant
shall be obligated to pay a late payment charge equal to five percent (5%) of
any Rent payment not paid when due, to reimburse Landlord for its additional
administrative costs.  Unless otherwise provided herein, any Additional Rent
which shall become due shall be payable with the next installment of Base Rent,
and if none is thereafter due, upon Landlord's demand therefor.  Rent and any
reports and statements required of Tenant shall be paid and delivered to
Landlord at the designated management office in the Building between the hours
of 8:00 a.m. and 6:00 p.m., Monday through Friday, or at such other place
reasonably acceptable to Tenant 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 from Tenant to Landlord shall be treated as a
payment on account. The acceptance by Landlord of a check for a lesser amount
with an endorsement  or statement 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 4.6.     Security Deposit.  INTENTIONALLY DELETED.

         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 which is not paid within five (5)
days after the same is 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; provided, however, that the terms of this Section 4.7 shall be waived the
first (1st) two (2) times in any twelve (12) month period that Tenant fails
timely to pay any Rent within such five (5) day period.





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<PAGE>   35
                                   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 vacates the Premises for a period exceeding three (3)
consecutive calendar months at any time during the Term, unless due to a
Casualty or approved Transfer, Landlord shall have the right (but not the
obligation) to terminate this Lease and recapture the Premises, but if Tenant
is not otherwise in default under this Lease, Landlord shall not be entitled to
recover damages or collect Rent (beyond the date of Landlord's termination) as
a result thereof.

         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
(excepting, however, Sundays and legal holidays).  If Tenant is operating
within the Premises for hours in excess of the stated operating hours and
requests additional HVAC service for such periods, then Tenant shall pay to
Landlord as Additional Rent, upon demand, any additional costs actually
incurred by Landlord in connection therewith.  The current costs to Landlord
for after hours HVAC is $48.00 per floor per hour.

         Section 5.3.  Operational Requirements.

         (a)  Landlord shall perform or provide certain standard building
services at, to or within the Building, a schedule of which is attached hereto
as Schedule B, in accordance with the standards of a modern, first-class office
building.  The cost of providing or performing the services are included within
the "Operating Costs" of the Building, a proportionate share of the increase to
which over those for calendar year 1996 shall be paid by Tenant in accordance
with the terms of this Lease.

         (b)  In regard to the use and occupancy of the Premises, Tenant shall,
at its expense: (i) keep the inside and outside of all glass doors of the
Premises clean; (ii) replace promptly any cracked or broken glass (except
exterior 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,





                                       25
<PAGE>   36
state, county and city laws, ordinances, codes, rules, regulations and
reasonable recommendations of Landlords's insurer or applicable fire insurance
rating organizations now or hereafter in effect; (vi) comply with and observe
all reasonable 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, provided the same are applied equally to all tenants of
the Building; 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.

         (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, except mail and packages, 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 will not place or maintain any matter on the glass of any
window, door or other portions of the Premises in such a manner as to be
visible from the exterior of the Premises, unless and to the extent approved by
Landlord as part of Tenant's Plans or as otherwise approved in writing by
Landlord.  Tenant shall, at its expense, maintain such sign, decoration,
lettering, advertising matter or other thing as may be permitted hereunder in
good condition and repair at all times.





                                       26
<PAGE>   37
         (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)  Tenant shall have the right, at its sole cost and expense (which
may be paid from the Allowance), to manufacture and affix and install (which,
again, may be paid from the Allowance) a sign on one side of the exterior of
the Building, which both parties agree shall be the Route 7 side of Leesburg
Pike at the approximate location of the current "AT&T" sign, which sign shall
be subject to the approval of any governmental or civic authority which has
jurisdiction thereover.  The existing AT&T sign shall be removed at Tenant's
sole cost and expense (which may be paid from the Allowance).  The design,
locations, materials, size and manner in which the name is attached to the
Building shall be acceptable in all respects to the Landlord in its reasonable
discretion.  Tenant shall at its sole cost and expense cause the sign to be
maintained, and the contractors or workmen responsible for maintaining the same
must perform their work in a manner which does not cause any damage to the
Building or unreasonably interfere with Landlord's maintenance of the Building.
Tenant shall obtain, at its cost, all permits and governmental consents
necessary for the sign.  Tenant shall be permitted to display the sign for so
long as Tenant occupies at least 43,398 square feet of GLA within the Building.

         (d) Tenant shall receive, at no charge to Tenant, up to eight (8)
strips for names and suite numbers on the directory in the lobby of the
Building; provided, however, that any subsequent changes to the names on the
directory shall be made at Tenant's  sole cost.

         (e) Landlord agrees that it shall not name the Building after Insignia
Financial Group, Inc., or any affiliate thereof.  

         Section 5.5.  Access Keys.

         If permitted by the Fairfax County Code, Tenant shall have the right,
at Tenant's cost (which cost may be paid from the Allowance), to install
security key locks and readers on the inside of both stairwells on the second
(2nd), third (3rd) and fourth (4th) floors so that Tenant's employees will be
able to use the stairs for internal access. If permitted, all such systems
shall be installed and maintained in compliance with applicable Fairfax County
and/or Virginia law; provided, however, that Tenant shall provide Landlord with
all keys or cards necessary to provide Landlord with access to the Premises.





                                       27
<PAGE>   38
                                   ARTICLE 6

                                     TAXES

         Section 6.1.  Real Estate Taxes.

         (a)  Beginning with the second (2nd) Lease Year during the Main Term,
and continuing for each successive Lease Year thereafter, Tenant shall pay in
each Tax Year, or portion thereof occurring during the Term, as Additional
Rent, Tenant's proportionate share of the increase to all Taxes over those
Taxes incurred by Landlord for the Project during calendar year 1996 (the "Tax
Base Year"), grossed up to reflect one hundred percent (100%) assessment at
full occupancy.  As used herein, "Taxes" shall mean amounts payable by Landlord
with respect to personal property taxes, 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 reasonable fees of
attorneys, consultants and appraisers in contesting any Taxes). Taxes shall not
include, nor shall Tenant be obligated to pay pursuant to this Section, such
taxes as capital gains, corporation, unincorporated business, income, profit,
excess profit, inheritance, transfer, recordation, estate, gift, or franchise
taxes, or license fees, or any taxes, fees, or charges imposed, assessed,
levied, or charged which are directly associated with construction of
improvements on the Project, or any vault rental or other vault charges, or any
fines, penalties, and interest on late payments of any taxes, or any personal
property taxes of Landlord for equipment or items not used directly in the
operation or maintenance of the Project or any withholding tax in the event the
Building is sold to a non-United States entity.

         (b)  The amount of Tenant's proportionate share of the increase in
Taxes ("Tenant's Taxes") for the second (2nd) and each successive Lease Year
shall be computed by multiplying the amount of such increase in Taxes over
those incurred in the Tax Base Year by the GLA Tax Fraction.  In the last Lease
Year of the Term the provisions of this Section shall apply, but Tenant's
liability for its proportionate share of any 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.





                                       28
<PAGE>   39
         (c) Landlord shall contest any Taxes imposed upon the Project if
requested to do so in writing by tenants occupying at least fifty percent (50%)
of the then-leased space within the Project.

         Section 6.2.  Payment of Tenant's Taxes.

         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 at the commencement of the second (2nd) Lease
Year during the Main Term.  Each installment is due on the first (1st) day of
each calendar month.  At any time or times during any Lease Year, Landlord may
reasonably revise its estimate of Tenant's Taxes and adjust Tenant's equal
monthly installments payable thereafter during such Lease Year to reflect such
revised estimate.  Any revised estimate shall include a reasonably detailed
explanation of the revision.  Within sixty (60) days after the date upon which
Landlord shall be obligated to pay any Tax, or such reasonable (in Landlord's
determination) time thereafter, Landlord shall certify to Tenant the amount of
Taxes allocated and assessed for the Lease Year in question and the amount of
Tenant's proportionate share thereof, which certification shall include a copy
of the tax bill at issue.  The proportionate share paid or payable for each
such Lease Year 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 for each such Lease Year.  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.  Notwithstanding anything herein to the
contrary, if it should thereafter be determined by a court of competent
jurisdiction that any abatement, waiver or release of any Taxes shall have been
invalid, the amount, if any, due from Tenant on account of Tenant's Taxes
during the then current and each prior Lease Year shall be redetermined for
purposes of this Lease as if such Taxes had been assessed and imposed without
regard to the effect of any such abatement, waiver or release thus determined
to be invalid, and any Additional Rent thereby determined to be due from Tenant
shall be paid to Landlord within thirty (30) days after receipt of notice from
Landlord.

         Section 6.3.     Refund of Taxes.

         Notwithstanding anything in Sections 6.1 or 6.2 to the contrary, if
any Taxes paid by Landlord and previously included





                                       29
<PAGE>   40
in payments made by Tenant pursuant to this Article are refunded, Landlord
shall promptly pay to Tenant Tenant's proportionate share of such refund (less
the reasonable expenses incurred by Landlord in obtaining such refund to the
extent not otherwise included in Taxes) based upon the proportion that the
Taxes paid by Tenant as part of Tenant's share of Taxes for the period to which
such refund relates bears to the total amount of Taxes paid by Tenant during
the calendar year to which such refund relates.

         Section 6.4.     Taxes on Rent and Other Taxes.

         In addition to Tenant's proportionate share of the increase in Taxes
over those paid by Landlord for the Tax Base Year and to the extent not
included in 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, levied, imposed or assessed by any governmental authority or other
taxing authority upon any Rent payable hereunder (collectively, "Rental Tax");
provided, that such Rental Tax is in addition to and not substitution of
existing Taxes.  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 its furniture, trade fixtures,
apparatus, equipment or 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 any other
property of Tenant; provided that Tenant shall have the right to contest any
such taxes.  Landlord may require that Tenant's leasehold improvements be
separately assessed by the taxing authority.

                                   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, which in no
way shall adversely or materially affect Tenant's use of the Common Areas.

         (b)     Landlord shall operate and maintain, or cause to be operated
and maintained, any areas designated by Landlord as Common Areas in a manner in
the best interests of the Project and





                                       30
<PAGE>   41
consistent with the highest standards of maintenance for a first-class office
building in Fairfax County, Virginia.  Landlord shall have the right from time
to time to take the following actions; provided, with respect to clauses (ii)
through (vi), that such changes do not adversely or materially affect Tenant's
use and occupancy of the Premises: (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 reasonably 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; (iii) to enter into, modify and
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 reasonable opinion
of Landlord, be necessary to prevent a dedication thereof or 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; provided, that if such closing
will adversely or materially affect Tenant's use and occupancy of the Premises,
Landlord may exercise this right if it provides Tenant with reasonable
alternative access or egress to and from the Premises; (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.

         "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 Building (including the
Premises) and the Common Areas located therein or within the Building and
serving or allocable to the Building, determined in accordance with generally
accepted accounting principles consistently applied from year to year,
including, without limitation, except as specifically set forth herein, all
costs and expenses of:

                 (a)  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);

                 (b)  purchasing and maintaining in full force insurance for
the Building (including, without limitation, liability insurance for personal
injury, death and property damage, rent





                                       31
<PAGE>   42
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 Building, and plate glass insurance)
(excluding, however, any costs for all insurance purchased by Landlord on
leasehold improvements in the premises of other tenants);

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

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

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

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

                 (g)      providing, electricity and heating, ventilation and
air conditioning to the Building and operating, maintaining and repairing any
equipment used in connection therewith (to the extent not specifically excluded
from Operating Costs); no replacement costs for major components of the
heating, ventilating or air conditioning system or energy costs are included in
this category;

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

                 (i)      enforcing any operating agreements pertaining to the
Building 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
Building, or any arbitration or judicial actions undertaken with respect to the
same;

                 (j)      maintaining and repairing the Building, 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

                 (k)      management fees (not to exceed four percent (4%) of
gross receipts generated from the operation of the Building;





                                       32
<PAGE>   43
provided, however, that if the management fee is increased, then the Base Year
Operating Costs shall be recalculated to include the amount of such increase)
and expenses and payroll and employee benefits of on-site personnel, (below the
level of property manager).

Notwithstanding anything contained herein to the contrary, and by way of
illustration and not limitation, Operating Costs (for the Building, Common
Areas or the Building, 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:

         (a)     Capital Expenditures, including any capital replacement,
capital repair or capital improvement 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.  Replacement of an item or of a major component of an
item and major repairs to such items in lieu of replacement shall each be
considered a Capital Expenditure if the original item or a subsequent
improvement to such item was, or could have been capitalized.

                 Capital Expenditures of $1,000 or less may be included in
Operating Costs.  For purposes of this clause, a group of expenditures related
to the same capital project shall be considered a single expenditure;

         (b)     Depreciation or amortization of the Building or its contents
or components;

         (c)     Expenses for the preparation of space or other work which
Landlord performs for any tenant or prospective tenant of the Building.

         (d)     Expenses incurred in leasing or obtaining new tenants or
retaining existing tenants, including leasing commissions, legal expenses,
advertising or promotion;

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

         (f)     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, other than Tenant, whether
or not Landlord is reimbursed by such other tenant(s);





                                       33
<PAGE>   44
         (g)     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 or for which Landlord is
reimbursed by other tenants or third parties, including insurance proceeds;

         (h)     The cost of correcting defects in the construction of the
Building, the Common Areas or the land; repairs resulting from ordinary wear
and tear shall not be deemed to be defects;

         (i)     Any costs of complying with any governmental laws, rules,
regulations, or other requirements applicable to the Land, the Building, the
Common Areas or the Premises;

         (j)     The cost of correcting any applicable building or fire code
violation(s) or violations of any other applicable law relating to the
Building, the Common Areas or the land; or the cost of any penalty or fine
incurred for non-compliance with the same;

         (k)     Any costs incurred to test, survey, cleanup, contain abate,
remove or otherwise remedy Hazardous Materials, as defined herein or asbestos
containing materials from the Building, the Common Areas, the Project or the
land (provided, that this exclusion from Operating Costs shall not affect the
provisions of this Lease or any other space lease at the Building with respect
to Tenant's or any other tenant's possible liability for all or a portion of
such costs);

         (l)     Any personal property taxes of Landlord for equipment or items
not used directly in the operation or maintenance of the Building;

         (m)     Contributions to Operating Costs reserves;

         (n)     All bad debt loss, rent loss, or reserve for bad debt or rent
loss;

         (o)     Costs incurred in connection with the sale, financing,
refinancing, mortgaging, selling, or change of ownership of the Building;

         (p)     Rentals and other related expenses incurred in leasing air
conditioning systems, elevators, or other equipment ordinarily considered to be
of a capital nature, except equipment not affixed to the Building which is used
in providing janitorial or similar services;

         (q)     Costs, other than those incurred in ordinary maintenance (for
such objects as may be located within the Common Areas), for sculpture,
paintings, or other objects of art;





                                       34
<PAGE>   45
         (r)     Taxes;

         (s)     Costs of repairs, restoration, replacements or other work
occasioned by (A) fire, windstorm or other casualty (whether such destruction
be total or partial) and (B) the exercise by governmental authorities of the
right of eminent domain (whether such taking be total or partial);

         (t)     Costs incurred in connection with disputes with tenants, other
occupants, or prospective tenants, or costs and expenses incurred in connection
with negotiations or disputes with employees, consultants, management agents,
purchasers or mortgagees of the Building;

         (u)     Costs incurred by Landlord which are associated with the
operation of the business of the legal entity which constitutes Landlord as the
same is separate and apart from the cost of the operation of the Building,
including legal entity formation and legal entity accounting (including the
incremental accounting fees relating to the operation of the Building to the
extent incurred separately in reporting operating results to the Building's
owners or lenders);

         (v)     Any compensation paid to clerks, attendants or other persons
in commercial concessions operated for profit by Landlord;

         (w)     Fees or expenses for management of the Building in excess of
the management fees provided for in Section 7.2(k);

         (x)     Costs incurred for any items to the extent covered by a
manufacturer's, materialman's, vendor's or contractor's warranty (a "Warranty")
and the costs of any items that are not covered by a Warranty but for which a
reasonable, prudent landlord would have obtained a Warranty;

         (y)     Any costs associated with retail space, unless such space is
not separately metered, including without limitation, electricity, HVAC and
other utilities; and

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

         Section 7.3.     Tenant's Operating Costs Charge.

         (a)     Beginning with the second Lease Year during the Main Term and
continuing for each successive Lease Year thereafter, 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 calendar year





                                       35
<PAGE>   46
1996 (the "Costs 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 Costs Base Year by the GLA Fraction.  Tenant's Operating Costs Charge
shall be paid by Tenant in monthly installments in such amounts as are
reasonably estimated and billed by Landlord at the beginning of each applicable
Lease Year, each installment being due with the monthly rent installment.
Landlord's bill to Tenant shall specify those Operating Costs that are
determined on a Project basis and those that are determined on a Building
basis.  Those Operating Costs that are determined on a Project basis shall be
allocated to the individual buildings comprising the Project on a fair and
reasonable basis.  The estimates provided at the beginning of each Lease Year
shall not exceed one hundred eight percent (108%) of the previous Lease Year's
allowable Operating Costs Charge, unless extraordinary events cause an excess
increase in a costs category, and evidence supporting the excess increase is
provided with such estimate.  From time to time during each Lease Year,
Landlord may reasonably revise its estimate of Tenant's Operating Costs Charge
and adjust Tenant's monthly installments payable thereafter during such Lease
Year to reflect such revised estimate.

         (b)     Notwithstanding any provisions of this Lease to the contrary,
Tenant shall not be obligated for pay for any annual increase in controllable
Operating Costs over the Base Year that exceeds one hundred eight percent
(108%) of the controllable Operating Costs for the previous year.
"Controllable" Operating Costs are all Operating Costs except for Taxes,
insurance and utilities.

         (c)     If at any time during the Lease Term, including calendar year
1996, less than 95% of the total rentable area of the Building is occupied by
tenants, or the Landlord is not supplying services to 95% of the total rentable
area of the Building at any time during any calendar year, the Operating Costs
for such calendar year shall 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 Building and had Landlord been supplying services to 95%
of the total rentable area of the Building 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 Expense statement.

         (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





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<PAGE>   47
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)     Upon at least ten (10) days' prior notice to Landlord and as
further described herein, Landlord shall permit Tenant's certified public
accountant or other representative to inspect, at Landlord's designated
management office during normal business hours, Landlord's records in regard to
Operating Costs for such preceding Lease Year; provided, however, that if
Tenant shall not have requested such inspection by written notice within three
(3) years following Tenant's receipt of the statement of Operating Costs for
such billing period, Tenant shall be conclusively deemed to have accepted such
statement and to have waived any further right to inspection.  If such records
relating to Operating Costs for the second or third preceding Lease Year are
not located within the Washington, D.C. metropolitan area, Landlord, at
Tenant's sole cost and expense, shall cause such records to be available
therein within ten (10) days after Tenant's request therefor, at Tenant's cost.
If Tenant's audit of the Operating Costs indicates that Tenant was overcharged
for the same, Landlord shall promptly repay all such overpayments to Tenant,
and adjust Tenant's Cost Base Year, if necessary.  If any Tenant's audit of the
Operating Costs indicates that Tenant was overcharged for the Operating Cost
Charge, by an amount which exceeds $4,500.00, Landlord shall promptly reimburse
Tenant for all of Tenant's expenses incurred for the audit.

         (f)     Provided that no uncured monetary or material non-monetary
Event of Default exists and is continuing, and further provided that space is
available in the Building and is not the subject of bona fide lease
negotiations or tenant construction, upon prior written notice to Landlord
received at least sixty (60) days prior to December 20, Landlord shall use
reasonable efforts to provide Tenant with approximately 5,000 to 10,000
rentable area of additional space in the Building for use and occupancy by
Tenant's auditors (the "Auditor's Space") for approximately 115 days during the
period between December 20 and April 30 of the following year during each Lease
Year during the Term (the "Audit Period").  Tenant shall pay the then-escalated
Base Rent, plus any Additional Rent applicable to the Auditor's Space, as Rent
for the Auditor's Space, payable under the same





                                       37
<PAGE>   48
conditions as Rent for the Premises prorated for any month of partial
occupancy.  The Auditor's Space shall be accepted in "AS-IS" condition, and
Landlord shall have no obligation to make alterations or improvements thereto.
Building services shall be provided to the Auditor's Space during regular
business hours.  Tenant acknowledges that Landlord reserves the right to
continue marketing any space occupied by Tenant's auditors, and to enter into
leases which would allow other occupied by Tenant's auditors, and to enter into
leases which would allow other tenants to occupy the Auditor's Space during the
Audit Period and require the removal of Tenant's auditors; provided, however,
that Tenant shall receive at least thirty (30) days notice from Landlord before
being required to vacate the Auditor's Space.  The Auditor's Space shall be
governed by the then current terms and conditions governing the Tenant's use
and enjoyment of the Premises including but not limited to compliance with the
Rules and Regulations.  During the time Landlord makes the Auditor's Space
available to the Tenant, it shall be conclusively deemed for all purposes
hereunder that Tenant's auditors are "Agents" for purposes of this Lease and
Tenant shall be responsible for the Auditor's Space and said Agents the same as
if the Auditor's Space was part of the Premises and the auditors were employees
of the Tenant.

         Section 7.4.     Parking Validation System.

         (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 Term, Landlord shall cause the parking garage operator
to provide to Tenant (at no additional cost to Tenant during the Main Term),
parking spaces based on the parking ratio of 3.5 spaces per 1,000 square feet
of GLA.  The parking spaces shall be located within the Parking Garage as for
Tenant's exclusive (with respect to the six (6) reserved spaces) or
non-exclusive (with respect to the remainder of the spaces) 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. The cost of striping and
designating the reserved spaces shall be paid from the Allowance, as described
in Section 2.3(a) above.  Landlord shall use its commercially reasonable
efforts to cause the Parking Garage operator to charge competitive hourly rates
for paid parking within the Parking Garage; provided, that Tenant's visitors
and invitees shall never be required to pay rates higher than the most
favorable rates charged to visitors and invitees of any other tenant within the
Project.

         (c)     Landlord hereby reserves the right, but shall have no
obligation, to establish a parking validation system ("the





                                       38
<PAGE>   49
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.  If a Parking Validation System is established,
then the Operating Costs for the Costs Base Year shall be recalculated as
though the costs of such Parking Validation System were imposed during the
Costs Base Year.


                                   ARTICLE 8

                             ENVIRONMENTAL COVENANT

         Section 8.1.  Environmental Covenant.

         In its use of the Premises and the remainder of the Building, the
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 Property, other than in accordance with
applicable law.

         Section 8.2.     Environmental Laws.

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

         (b)     The Landlord has not caused or explicitly consented to the
unlawful storage or disposal of any hazardous substances or materials within
the Project.  The Landlord has not received notice of any decree, judgment, or
order of an actual or alleged environmental contamination within the Project.
If the Premises become contaminated by any hazardous materials, which
contamination shall not have resulted from any action or cause of Tenant, then
Landlord shall pay for the cost of any required decontamination, removal and
replacement of such items.





                                       39
<PAGE>   50
         Section 8.3.     Indemnity.

         If any governmental agency ever requires testing to ascertain whether
or not there has been any release of hazardous materials within the Premises
during the term of this Lease, then Tenant's proportional share of the
reasonable costs thereof shall be reimbursed by the Tenant to the Landlord upon
ten (10) days' demand as additional charges if such requirement applies to the
Premises.  The Tenant shall execute affidavits, representations and the like
from time to time at the Landlord's request concerning the Tenant's best
knowledge and belief regarding the presence of hazardous substances or
materials on the Premises.  Landlord and Tenant shall each defend, indemnify
and hold harmless the other against and from any liability, claim of liability
or expense arising out of any release of hazardous materials on the Premises or
Building occurring while each is in possession thereof, or if incurred by
Landlord elsewhere in the Project if caused by the Tenant.

         Section 8.4.     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 and Building
Systems.

         Landlord shall maintain or cause to be maintained the structure of the
Building and shall be responsible for:  (a) repairs to any mechanical,
electrical, plumbing, sprinkler system or other life saving systems or HVAC
system installed by or on behalf of Landlord and serving the Premises and
Common Areas, 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 Tenant shall give Landlord notice of, or Landlord has
actual knowledge of, the necessity for such repairs (which notice may be given
telephonically to Landlord's on-site management agent).  If the necessity for
such repairs shall have arisen, in whole or in part, from the willful acts or
omissions of Tenant or entities for which Tenant is responsible and the
insurance that Landlord is required to carry excludes from coverage any
casualty willfully caused by Tenant or entities for which Tenant is
responsible, then Tenant shall pay any amount not covered by Landlord's
insurance.





                                       40
<PAGE>   51
         Section 9.2.     Tenant's Duty to Maintain Premises.

         (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 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 and
Article 12 and subject to the terms of Section 10.8).  Without limiting the
generality of the foregoing, Tenant shall: (i) keep the interior of the
Premises, together with all of its specialized systems and its 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;
and (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 as
provided in the last sentence of Section 9.1 above, or condemnation, 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.
Landlord acknowledges, after due inquiry, that if used in the normal course of
business, the electrical equipment installed as part of Tenant's Plans for the
initial improvements to the Premises will not overload the electrical wiring
system.  If the necessity for such repairs shall have arisen, in whole or in
part, from the willful acts or omissions of Landlord or entities for which
Landlord is responsible and the insurance that Tenant is required to carry
excludes from coverage any casualty willfully caused by Landlord or entities
for which Landlord is responsible, then Landlord shall pay any amount not
covered by Tenant's insurance.

         (b)  Any damage or injury sustained by any person because of any
equipment or installation, the maintenance and repair of which is the
responsibility of Tenant pursuant to this Section, shall be paid for by Tenant.

         (c)  Notwithstanding anything contained in this Article 9 to the
contrary, Tenant's duties under this Section 9.2 and Section 9.3, below, are
subject to Landlord's maintenance and repair obligations under this Article 9,
the terms of Section 10.8, below, and Landlord's obligations under Articles 11
and 12, below.





                                       41
<PAGE>   52
         Section 9.3.     Tenant's Duty to Repair Damage.

         Any repairs or alterations to the Premises which may affect the
structure or external appearance of the Premises, any Common Areas or any
portion of the Building, shall require the prior written consent thereto by
Landlord.  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 or the Building outside of the Premises.  In default of the making
of such repairs by Tenant, at the expiration of thirty (30) days after notice
to Tenant (which notice shall not be required in emergency situations),
Landlord may make such repairs or cause the same to be made, and Tenant agrees
to pay to Landlord promptly upon Landlord's demand, as Additional Rent, with
interest at the Default Rate until paid, the reasonable amount incurred by
Landlord.  Any repairs made by Landlord, without notice due to an emergency
situation shall not incur interest at the Default Rate.

         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.  All such work shall comply with all applicable
governmental codes, rules, regulations and ordinances.  Notwithstanding the
foregoing, Tenant shall have the right, without Landlord's consent (Tenant
must, however, provide notice to Landlord in accordance with the terms of this
Section), to repaint and/or recarpet all or any portion of the Premises at any
time or from time to time or to make any non-structural alteration the cost of
which does not exceed $10,000 for any alteration project.

         Section 9.5.     Landlord's Right of Access.

         Except in case of an emergency (in which case Landlord may enter the
Premises at any time without notice) and provided





                                       42
<PAGE>   53
Landlord provides Tenant with reasonable prior notice, minimizes the
interference of Tenant's business, and is accompanied by a representative of
Tenant, if requested, 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 or the Building; (b) use
exclusively all or any part of the roof, if any, of the Premises for any
purpose, including, without limitation, the erecting of temporary scaffolds and
other aids to construction on the exterior of the Premises, 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, 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.


                                   ARTICLE 10

                            INDEMNITY AND INSURANCE

         Section 10.1.    Tenant's Insurance.

         At all times from and after entry by the Tenant into the Premises 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:

                 (a)  Commercial general liability insurance, including Blanket
Contractual Liability, Broad Form Property Damage, Completed
Operations/Products Liability, Coverage for Employees as insureds, and Broad
Form General Liability Endorsement, with a combined single limit of not less
than Three Million Dollars ($3,000,000) per occurrence and Four Million Dollars
($4,000,000) in the aggregate;

                 (b)  All-risk casualty insurance (including but not limited to
burglary and theft insurance) written at full replacement cost value and with
replacement cost endorsement covering (i) all of Tenant's Property, including,
without limitation, inventory, trade fixtures, floor covering, 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





                                       43
<PAGE>   54
behalf of Tenant pursuant to Schedule C or otherwise, regardless of the source
of funding thereof;

                 (c)  Worker's compensation or similar insurance to the extent
and in the amounts required by law;

                 (d)  Employer's Liability insurance, including All States
Endorsement in an amount not less than Five Hundred Thousand Dollars
($500,000); and

                 (e)  Comprehensive automobile liability coverage 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).

         Section 10.2.    Tenant's Contractor's Insurance.

         Tenant shall require any contractor of Tenant performing physical
improvements and/or changes 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, including
Contractor's Liability coverage, Blanket Contractual Liability coverage, Broad
Form Property Damage Endorsement, Contractor's Protective Liability, Completed
Operations/Products Liability Interest of Employees as insureds, and Broad Form
General Liability Endorsement, in an amount not less than One Million Dollars
($1,000,000) Endorsement, in an amount not less than One Million Dollars
($1,000,000) combined single limit per occurrence and One Million Dollars
($1,000,000) in the aggregate;

                 (b)  Comprehensive automobile liability insurance, with a
combined single limit of not less than One Million Dollars ($1,000,000)
covering all owned, non-owned or hired automobiles to be used by the
contractor;

                 (c)  Worker's compensation or similar insurance in form and
amounts required by law; and

                 (d)  Employers liability coverage, including All States
Endorsement in an amount not less than One Million Dollars ($1,000,000).

         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, shall be written by companies licensed to
do business in the Commonwealth of Virginia and have a Best rating of at least
A-VII with respect to Tenant or A-VI with respect to contractors or
subcontractors.  Public liability and all-risk casualty insurance policies





                                       44
<PAGE>   55
evidencing such insurance shall name Landlord and/or its designees (including,
without limitation, any Mortgagee) as additional insureds, and shall also
contain a provision by which the insurer agrees that such policy shall not be
cancelled, materially changed, terminated or not renewed except after thirty
(30) days' advance written notice to Landlord and/or such designees.  All such
policies, or certificates thereof, 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, unless approved in writing in advance by Landlord.  If
Tenant shall fail to perform any of its obligations pursuant to this Section
10.1, 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 of the second (2nd)
full Lease Year and on January 1 of every second (2nd) Lease Year thereafter,
Landlord will have the right to request a reasonable 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, the Tenant shall comply with the
requested change in character and/or amount within sixty (60) days of
Landlord's request therefor.

         Section 10.4.    Indemnities by Tenant and Landlord.

         (a)  Notwithstanding any policy or 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,
Landlord's Management Agent, and any Mortgagee against and from any and all
liability or claims of liability asserted against or incurred by Landlord in
connection with (i) the use, occupancy, conduct, operation 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, concessionaires, 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 unless caused by the negligence or willful misconduct of
Landlord, its agents or employees.





                                       45
<PAGE>   56
         (b)  Notwithstanding any policy or policies of insurance required of
Landlord, Landlord, for itself, and its successors and assigns, to the extent
permitted by law, shall defend, indemnify and hold harmless Tenant against and
from any and all liability or claims of liability asserted against or incurred
by Tenant in connection with (i) the use, occupancy, conduct, operation or
management of the Project by Landlord 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
Landlord or any of its agents, contractors, servants, employees, licensees,
concessionaires, suppliers or materialmen during the Term; or (iii) any
negligent, intentionally tortious or other act or omission by Landlord or any
of its agents, contractors, servants, employees, licensees, concessionaires,
suppliers, materialmen or invitees during the Term, unless caused by the
negligence or willful misconduct of Tenant, its agents or employees.

         (c)  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.

         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 for any loss
or damage resulting to Tenant (or those claiming by, through or under Tenant),
or 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 as Tenant is herein given the
right to use, at Tenant's own risk (provided, that this sentence shall not be
deemed to negate Landlord's indemnification contained in Section 10.4(b)).





                                       46
<PAGE>   57
         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 against loss or caused by all risks perils on a replacement cost
valuation basis in an amount deemed reasonable by Landlord, (b) commercial
liability insurance including property damage insurance against claims for
personal injury or death, or property damage suffered by others occurring in,
on or about the Building, such public liability insurance to afford protection
in limits deemed reasonable by Landlord but in no event less than $10,000,000
in the aggregate for this location, 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 for up to
twelve (12) months in each instance, theft insurance and worker's compensation,
flood and earthquake, and boiler and machinery insurance.  Landlord's insurance
shall be written with companies licensed to do business in the Commonwealth of
Virginia having a Best rate of at least A-VII.  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 to be increased
beyond the average 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.    Mutual Waiver.

         All policies covering real or personal property which either party
obtains affecting the Premises or the Building 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





                                       47
<PAGE>   58
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.

                                   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 unless Tenant cannot use the Premises
during such repair period, or if the Premises are not reasonably accessible, in
which event Rent shall be abated retroactive to the date of the occurrence.  If
as the result of Casualty, the Premises shall be rendered wholly or partially
untenantable or not reasonably accessible, or the parking area was damaged to
the extent that Tenant could not use the same (and no proximate comparable
alternate facility in the Fairfax County, Virginia area was offered), then,
subject to the provisions of Section 11.2, Landlord shall cause such damage to
be repaired to the condition which existed immediately prior to such Casualty,
provided that Tenant provides Landlord with all insurance proceeds applicable
to Tenant's improvements within the Premises received by Tenant as a result of
such Casualty, 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.  In performing its rebuilding obligations
hereunder, Landlord shall have the right to make modifications to the
structures comprising the Building and the Premises provided that such
modifications do not materially adversely affect Tenant's use and occupancy of
the same.  Landlord shall not be liable for interruption to Tenant's business
or for damage to or replacement or repair of Tenant's Property, all of which
damage, replacement or repair shall be undertaken and completed promptly by
Tenant at Tenant's expense.

         In addition to the foregoing, if the Premises or the Building are
totally destroyed by fire or any other casualty, this Lease shall automatically
terminate as of the date of such destruction.  If the Building or any portion
of the Common Areas or Premises are damaged by fire, casualty, or any other
cause, and such damage is repairable, then Landlord, at Landlord's sole





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cost and expense (except for Tenant's personal property), shall commence
repairs within sixty (60) days of the date of the casualty, and shall
thereafter diligently complete the repairs in accordance with the requirements
of this Article 11.  Until such repairs and restoration are completed, the
Rent, as defined herein, and any other sums due to Landlord, shall be abated.
If the damage cannot be repaired, or if such damage is in fact not repaired,
within nine (9) months from the date of such casualty (in the reasonable
judgment of an independent architect), due to any reason within or outside of
the Landlord's control, then Tenant shall have the option to terminate this
Lease, without penalty or default, by giving Landlord written notice of such
termination; provided, however, that if Landlord, within thirty (30) days of
the expiration of the nine (9) month period, shall notify Tenant that the
repairs and restoration shall be complete within thirty (30) days after the
expiration of the nine (9) month period and the repairs and restoration are, in
fact, so completed, Tenant shall have no termination right under this section.
Tenant shall vacate the Premises within thirty (30) days after the date of such
termination.

         Section 11.2.    Landlord's Option to Terminate Lease.

         If (a) the Premises or Building or Project are rendered wholly
untenantable and cannot be repaired within nine (9) months, or (b) the Premises
are damaged as a result of any cause which is not covered by Landlord's
insurance and the cost to repair the Premises would reasonably exceed $500,000,
or (c) the Premises are damaged or destroyed in whole or in part during the
last twelve (12) months of the Term (unless Tenant exercises its renewal
option, if applicable), or (d) 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 may elect to terminate this Lease by
giving Tenant notice of such election within sixty (60) 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.  Tenant shall vacate the Premises within thirty (30) days after
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





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<PAGE>   60
payable to Tenant pursuant to Section 10.1), shall belong to and shall be
payable to Landlord.

                                   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.  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 twenty-five
percent (25%) or more of the Premises is taken (and in Tenant's good faith
judgment the balance is not suitable for Tenant's business operations), Tenant
may elect to terminate this Lease as of the date of such taking by giving
notice of that election to Landlord within ninety (90) days after the date of
the taking.  If any notice of termination is given pursuant to this Section,
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, expenses for
removal of Tenant's Property or loss of Tenant's business good will, but if and
only if such action shall not reduce the amount of the award or other
compensation





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<PAGE>   61
otherwise recoverable from the condemning authority by Landlord or any
Mortgagee.

                                   ARTICLE 13

                           ASSIGNMENT AND SUBLETTING

         Section 13.1.    Landlord's Consent Required.

         (a)     Tenant shall not assign this Lease, in whole or in part, nor
sublet all or any part of the Premises, nor license concessions or lease
departments therein, 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.  This prohibition includes any
subletting or assignment to or by a receiver or trustee in any Federal or State
bankruptcy, insolvency, or other similar proceedings.  Consent by Landlord to
any assignment, subletting, licensing or other transfer shall not constitute a
waiver of the requirement for consent to any subsequent assignment, subletting,
licensing or other Transfer or relieve Tenant from its duties, responsibilities
and obligations under this Lease.

         (b)     Notwithstanding any provision herein to the contrary, Tenant
shall have the right, without Landlord's consent, to assign the Lease or to
sublet all or any part of the Premises to an entity which controls, is
controlled by, or is under common control with, Tenant or to an entity with
which Tenant merges or consolidates or which acquires all or substantially all
of Tenant's assets.  In addition, Tenant shall have the right without the
consent of Landlord to allow any affiliate of Tenant to use or occupy any
portion of the Premises, provided that such use or occupancy is pursuant to a
written agreement between Tenant and its applicable affiliate.

         Section 13.2.    Transfer; Issuance of Corporate Shares.
INTENTIONALLY DELETED.

         Section 13.3.    Acceptance of Rent from Transferee.

         The acceptance by Landlord of the payment of Rent from any person
following any act, assignment or other Transfer prohibited by this Article
other 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 other than a sublet
under Section 13.1 above, then, in addition to any other





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<PAGE>   62
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 agreeing 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 therein;
acknowledging and agreeing that there shall be no subsequent Transfer other
than a sublet of this Lease or of the Premises or of any interest therein
without the prior consent of Landlord pursuant to Section 13.1 above;
acknowledging that Tenant as originally named herein shall remain fully liable
for all obligations of Tenant hereunder, jointly and severally with the
transferee; and such other provisions as Landlord shall reasonably require.

         (b)     All reasonable costs incurred by Landlord in connection with
any request for consent to a Transfer, including costs of investigation and the
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.

         (a)     Neither the Tenant nor by any other person having an interest
in the use, occupancy or other utilization of space in the Premises shall enter
into any lease, sublease, license, concession or other Transfer which provides
for rent or other payment for such use, occupancy or utilization based in whole
or in part on the net income or profits derived from the Premises (other than
an amount based on a fixed percentage of receipts or sales), and any such
purported lease, sublease, license, concession or other Transfer shall be
absolutely void and ineffective as a conveyance or creation of any right or
interest in the possession, use, occupancy or utilization of any part of the
Premises.

         (b)     Tenant agrees that in the event of a Transfer, Tenant shall
pay Landlord thirty percent (30%) of any and all consideration, money or thing
of value received by Tenant or payable to Tenant in connection with such
Transfer and in excess of the rent payable by Tenant under the Lease (but not
including any consideration for the sale of any personal property of Tenant).





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<PAGE>   63
                                   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 five (5) days after
written notice that the same is due;

                 (b)  sale of Tenant's interest in the Premises under
attachment, execution or similar legal process;

                 (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 or any such guarantor and is withdrawn or dismissed
within ninety (90) 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 written notice thereof by
Landlord, unless such 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 the thirty (30) day
period and thereafter diligently and continuously prosecutes the same until
completion.

         Notwithstanding the foregoing, if Tenant shall default in the
performance of any covenant or agreement two (2) or more times in any twelve
(12) month period, then, unless such default(s) shall have been cured within
the applicable notice and grace period, any further similar defaults shall be
deemed an Event of Default without the ability to cure.





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         Section 14.2.    Remedies.

         Upon the occurrence of an Event of Default, Landlord, without
additional 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 as more particularly
described in Section 14.3(a) below; and/or

                 (b)  Landlord may elect to terminate this Lease and the
tenancy created hereby by giving notice of such election 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, term, agreement or covenant broken.
Landlord may also elect to terminate Tenant's possessory rights and all other
rights of Tenant without thereby terminating this Lease, and 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, for the purpose of exercising
Landlord's lien against Tenant's property, 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; and/or

                 (c)  When this Lease shall be terminated by covenant or
condition broken, either during the original Term or any renewal or extension
thereof, and, also when and after the Term shall have 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 by Landlord of
possession of the Premises.  If for any reason after such action shall have
been commenced, it shall be cancelled 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, or any renewal or extension hereof, to bring one or more actions to
recover possession of the Premises; and/or

                 (d)  If a true copy of this Lease (and of the truth of the
copy, an affidavit shall be sufficient proof) is required to be filed in any
action for possession or enforcement or monetary damages, it shall not be
necessary to file the original,





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<PAGE>   65
notwithstanding any law, rule of court, custom or practice to the contrary.
Tenant hereby waives all procedural errors in any proceedings taken by
Landlord, other than service of process, whether by virtue of the powers of
attorney contained in this Lease or not, and all liability therefor; and/or

                 (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.  Notwithstanding anything
to the contrary contained herein, regardless of whether an Event of Default
shall have occurred, Landlord may exercise the remedy described in this clause
(f) without any notice to Tenant if Landlord, in its good faith judgment,
believes it would be materially injured by failure to take rapid action or if
the unperformed obligation of Tenant constitutes an emergency.

                 (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 nevertheless shall remain liable for any Rent and damages which may be
due or sustained prior to such termination, and all reasonable costs, fees and
expenses, including, without limitation, sheriffs' or other officers
commissions whether chargeable to Landlord or Tenant, watchmen's wages,
brokers' and reasonable 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 (which costs and expenses shall be
prorated based on the term of the new lease and the then remaining term of this
Lease) (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 or
amounts 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





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<PAGE>   66
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 amount, if any, by which (i) 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, exceeds
(ii) the present worth (as of the date of such termination) of the fair rental
value of the Premises, as reasonably 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.

         (b)  If this Lease is terminated pursuant to Section 14.2, Landlord
shall make reasonable efforts to relet the Premises or any part thereof
(provided that Landlord shall not be obligated to relet the Premises in
preference to any other available space within the Project or within other
projects owned by Landlord's shareholder), 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 sole discretion,
but, so long as Landlord makes reasonable efforts to relet the Premises,
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
subsection 14.3, in the event following and during the continuance of an Event
of Default, (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, any
guarantor of Tenant, their successors or assigns, or





                                       56
<PAGE>   67
(B) in connection with any bankruptcy proceeding of Tenant or any guarantor 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 any and 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, NONDISTURBANCE AND ATTORNMENT

         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 or noteholder, being referred to hereinafter
collectively as a "Mortgagee").  Landlord and all existing Mortgagees shall
execute and deliver the Subordination, Non-Disturbance and Attornment Agreement
in the form attached as Schedule G at the time of the execution of this Lease.
For any future Mortgage, as a condition to Tenant's obligation to subordinate
the Lease to any future Mortgage, such Mortgagee shall execute, acknowledge and
deliver to Tenant a similar non-disturbance agreement as part of such
subordination.  Upon receipt of such non-disturbance agreement for such future
Mortgage, Tenant's acknowledgment and agreement of subordination as provided
for in this Section shall be self-operative and no further instrument of
subordination shall be required.  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.  On the
date hereof, the only Mortgagee is Teachers Insurance and Annuity Association
of America.

         (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





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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.

         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 as is reasonably
acceptable to such successor-in-interest.  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, except as otherwise
provided in this Lease, upon the continuing compliance by Tenant with all of
the terms, covenants and provisions of this Lease to be performed by Tenant,
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.





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                                   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 (i) 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 (ii) the next day if sent by national overnight
courier service with receipt acknowledged in writing, or (iii) on the day
received if sent by facsimile with printed confirmation of receipt (and with a
hard copy sent by U.S. mail) 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.

         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 default notice or demand thereafter sent by Tenant to
Landlord shall 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.  Landlord agrees to
provide a similar certificate to Tenant on the same terms.





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                                   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 on 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.    Memorandum of Lease.

         (a)     Landlord and Tenant shall, at the request of either party,
execute, acknowledge and deliver to the other party a memorandum of this Lease
(the "Lease Memorandum") in recordable form, setting forth the date of this
Lease, the names of the parties hereto, the Rent Commencement Date and
describing the Premises and Tenant's expansion options, Tenant's rights to
renew this Lease and the Project.  Said Lease Memorandum shall not in any
circumstances be deemed to modify or to change any of the provisions of this
Lease.  Tenant may elect, at its sole expense, to record the Lease Memorandum.

         (b)     In the event that Landlord and Tenant execute such Lease
Memorandum, each party shall after the expiration or termination of the Term,
at the request of the other party, execute, acknowledge and deliver a
memorandum in recordable form evidencing the expiration or termination of this
Lease, and if such party fails to execute such memorandum within fifteen (15)
days after the date of such request, such party hereby irrevocably appoints the
requesting party as its attorney-in-fact to execute and deliver such memorandum
on behalf of such party.  The memorandum of termination shall be recorded at
Tenant's expense.

         Section 18.3.    Remedies Cumulative.

         No reference to any specified right or remedy shall preclude either
party 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 either party to insist upon the strict performance of
any agreement, term, covenant or condition hereof, or to exercise any right
remedy consequent upon a breach hereof, and no acceptance of full





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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 either party any breach by the other party under this Lease (or any waiver
by Landlord of any breach by any other tenant under any other lease of any
portion of the Building) 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 13,
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.

         (a)     Tenant, at its expense, shall comply with and shall cause the
Premises to comply with all federal, state, municipal and other governmental
statutes, laws, rules, orders, regulations and ordinances (including, without
limitation, environmental laws, rules, orders, regulations and ordinances)
relating to Tenant's particular use and occupancy of 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.
Tenant's construction and design of the improvements (as described in Article
2) shall be in compliance with, inter alia the ADA.  Tenant shall also, at its
expense, comply and cause the Premises to comply with 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, subject to Section
2.5(a) above, 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.

         (b)     Landlord, at its expense, shall comply with and shall cause
the Common Areas to comply with all federal, state,





                                       61
<PAGE>   72
municipal and other governmental statutes, laws, rules, orders, regulations and
ordinances (including, without limitation, environmental laws, rules, orders,
regulations and ordinances) affecting the Common Areas 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.  Landlord shall
also, at its expense, comply with all rules, orders and regulations of the
National Board of Fire Underwriters or the Landlord's fire insurance rating
organization or other bodies exercising similar functions in connection with
the prevention of fire or correction of hazardous conditions, which apply to
the Building.

         Section 18.6.    Captions and Headings.

         The Table of Contents, the Table of Defined Terms 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.    Broker's Commissions.

         Tenant represents and warrants to Landlord that it has dealt directly
with and only with Grubb & Ellis of Metropolitan Washington, D.C. ("G&E") as
Tenant's authorized representative, and Landlord and Landlord's leasing agent
recognize G&E as Tenant's authorized representative.  Landlord shall pay G&E
for its services in connection with this Lease pursuant to a separate
agreement.  Landlord represents that Landlord has dealt directly with and only
with Faison & Associates, Inc. ("Faison") as its authorized representative, and
Tenant and G&E recognize Faison as





                                       62
<PAGE>   73
Landlord's authorized representative.  Landlord shall pay Faison 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.

         Section 18.11.   Schedules.

         Any documents attached hereto as Schedules, together with all drawings
and documents prepared pursuant thereto or referred to therein are hereby
incorporated herein and made a part hereof.

         Section 18.12.   Severability.

         If any term or provisions, 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.





                                       63
<PAGE>   74
         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.

         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 hereto and other persons
have been joined.

         Section 18.17    Limitation of Liability.

         (a)     Anything contained in any provisions 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 (and with respect to items (ii) through
(vii), except in each instance for any act or omission taken by any below-named
person in an individual capacity, acting outside of the scope of such person's
corporate authority where such act or omission would subject such person to
personal liability under applicable law):





                                       64
<PAGE>   75
             (i)          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;

             (ii)         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 (except when required for procedural purposes);

            (iii)         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 (except when required for procedural purposes);

             (iv)         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 (except when required for procedural purposes);

             (v)          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;

             (vi)         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;

            (vii)         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 (i) of this Section 18.17(a); and

         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.





                                       65
<PAGE>   76
         (b)     Anything contained in any provision of this Lease to the
contrary notwithstanding, in consideration of the benefits accruing hereunder,
Landlord, 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
Tenant, its successors or assigns (and except in each instance for any act or
omission taken by any below-named person in an individual capacity, acting
outside of the scope of such person's corporate authority where such act or
omission would subject such person to personal liability under applicable law):

              (i)         no partner, officer, director, or stockholder of
Tenant or partner, trustee, officer, director, or stockholder of any entity
having a direct or indirect financial interest in Tenant, and no employees or
agents of any such entities, shall be sued or named as a party in any suit or
action (except when required for procedural purposes);

             (ii)         no service of process shall be made against any
partner, officer, director, or stockHolder of Tenant or against any partner,
trustee, officer, director, or stockholder of any entity having a direct or
indirect financial interest in Tenant (except when required for procedural
purposes);

            (iii)         no partner, officer, director, or stockholder of
Tenant or partner, trustee, officer, director, or stockholder of any entity
having a direct or indirect financial interest in Tenant, and no employees or
agents of any such entities, shall be required to answer or otherwise plead to
any service of process (except when required for procedural purposes);

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

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

             (vi)         no writ of execution shall ever be levied against the
assets of any partner, officer, director, or stockholder of Tenant, or against
the assets of any partner, trustee, officer, director, or stockholder of any
entity having a direct or indirect financial interest in Tenant, or against the
assets of any trustee, employee, or agent of any such entities.





                                       66
<PAGE>   77
         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    Net Lease.  INTENTIONALLY DELETED.

         Section 18.22    Consents.  In any instance in which either Landlord
or Tenant shall be requested to consent or approve any matter with respect to
which such party's consent or approval is required by any of the provisions of
this Lease, such consent or approval shall not be unreasonably withheld,
conditioned, delayed, or exercised except as may otherwise be expressly set
forth to the contrary in this Lease.

         Section 18.23    Unilateral Amendment.

         Landlord shall have the right at any time, and from time to time,
during the Term of this Lease, to unilaterally amend the provisions of this
Lease if Landlord is advised by its counsel that all or any portion of the
monies paid by Tenant to Landlord hereunder are, or may be deemed to be,
unrelated business income within the meaning of the United States Internal
Revenue Code or regulations issued thereunder, and Tenant agrees that it will
execute all documents or instruments necessary to effect such amendment or
amendments, provided that no such amendment shall result in Tenant having to
pay in the aggregate a larger sum of money on account of its occupancy of the
Premises under the terms of this Lease as so amended, and provided further that
no such amendment or amendments shall result in Tenant receiving under the
provisions of this Lease less services than it is entitled to receive, nor
services of a lesser quality; provided, however,





                                       67
<PAGE>   78
that Tenant shall suffer no material or adverse effect as a result of any such
amendment.

         Section 18.24  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 19.14.  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.





                            [SIGNATURE PAGE FOLLOWS]





                                       68
<PAGE>   79
         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:

                                           FAIRFAX SQUARE ASSOCIATES II,
                                           A VIRGINIA GENERAL PARTNERSHIP

                                           By: MAV Properties, Inc., a
                                               general partner


          [SIG]                            By:/s/ JAMES M. FITZPATRICK (SEAL)
---------------------------                   ------------------------
                                                  JAMES M. FITZPATRICK
                                                  VICE-PRESIDENT



ATTEST OR WITNESS:                         TENANT:

                                           NHP INCORPORATED, A DELAWARE
                                           CORPORATION


          [SIG]                            By:         [SIG]              (SEAL)
-----------------------------                 -----------------------------
SECRETARY                                     PRESIDENT AND CHIEF EXECUTIVE
                                              OFFICER


APPROVED, THIS 8th DAY OF December, 1995, AS MORTGAGEE HEREUNDER, PURSUANT
TO SECTION 18.1 OF THIS LEASE.

TEACHERS INSURANCE AND ANNUITY
   ASSOCIATION OF AMERICA


By:       [SIG]            (SEAL)
   ------------------------
         DIRECTOR




                         [ACKNOWLEDGMENTS ON NEXT PAGE]





                                       69
<PAGE>   80
                                ACKNOWLEDGMENTS

STATE OF ___________________      )
                                  )        TO WIT:
CITY/COUNTY OF _____________      )

         I HEREBY CERTIFY that on this 8th day of December, 1995, before me,
the subscriber, a Notary Public in and for the State referenced above,
personally appeared JAMES FITZPATRICK, who acknowledged himself to be the
Vice-President of MAV Properties, Inc., a general partner of Fairfax Square
Associates II, a Virginia general partnership, and did acknowledge that he as
such Vice-President of MAV Properties, Inc., a general partner of Fairfax
Square Associates II, executed the foregoing Office Lease Agreement for the
purposes therein contained, and further acknowledged the foregoing Office Lease
Agreement to be the act of the said MAV Properties, Inc., a general partner of
Fairfax Square Associates II.

         AS WITNESS my hand and notarial seal.

                                             /s/ Carmen Lowmark
                                             -----------------------------------
                                             Notary Public

My Commission Expires:    CARMEN LOWMARK
                        -----------------------
                        Notary Public, State of N.Y.
                              No. 43-5011109
                        Qualified in Richmond County
                        Comm. Expires April 12, 1997

City of Washington           )
                             )        TO WIT:
District of Columbia         )

         I HEREBY CERTIFY that on this 6th day of December, 1995, before me, the
subscriber, a Notary Public in and for the jurisdiction referenced above,
personally appeared J. Roderick Heller, III, who acknowledged himself/herself to
be the President and CEO of NHP Incorporated, a Delaware corporation, and did
acknowledge that he as such President and CEO of NHP Incorporated executed the
foregoing Office Lease Agreement for the purposes therein contained, and further
acknowledged the foregoing Office Lease Agreement to be the act of the said NHP
Incorporated.         

         AS WITNESS my hand and notarial seal.

                                                        [SIG]
                                             -----------------------------------
                                             Notary Public

My Commission Expires:  September 30, 1997      
                        -----------------------




                                       70
<PAGE>   81
                                  SCHEDULE A
                                      
                         DRAWING SHOWING APPROXIMATE
                           LOCATION OF THE PREMISES
                                      
                                  [FIGURE 1]
<PAGE>   82
                                 FAIRFAX SQUARE

                                  SCHEDULE A-1

                          LEGAL DESCRIPTION OF PROJECT


         ALL of that certain property located in Fairfax County, Virginia,
described as follows, subject to a Deed of Trust:

         Beginning at a point on the Southeasterly side of Aline Avenue (Route
3402) said point marking the P.C. of a return at the Southeasterly corner of
the intersection of Aline Avenue and Leesburg Pike (Route #7) as recorded among
the land records of Fairfax County, Virginia, in Deed Book 3578 at page 478;
thence with the Southwesterly side of Leesburg Pike the following courses: with
a curve to the right whose radius is 25.00 feet (and whose chord is N 88
degrees 58'57" E, 36.27 feet) an arc distance of 40.58 feet; S 44 degrees
30'41" E, 111.47 feet; with a curve to the left whose radius is 1945.08 feet
(and whose chord is S 46 degrees 17'41"E, 121.06 feet) an arc distance of
121.08 feet and S 48 degrees 04'41" E, 316.79 feet to a point on the Westerly
line of Builder of Northern Virginia, Inc.; thence with the Westerly and
Southerly lines of Builders of Northern Virginia, Inc., S 30 degrees 57'53" W,
431.98 feet and S 56 degrees 22'15" E, 20.74 feet to a point; thence running
through the property Freedom Hill Limited Partnership S 42 degrees 28'33" W,
295.93 feet N 47 degrees 31' 27" W, 682.15 feet to a point on the
aforementioned Southeasterly side of Aline Avenue; thence with the
Southeasterly side of Aline Avenue N 42 degrees 28'33" E, 696.46 feet to the
point of beginning, containing 10.58441 acres of land.
<PAGE>   83
                                 FAIRFAX SQUARE

                                   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 ash trays 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.
<PAGE>   84
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.

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.





                                       2
<PAGE>   85
         9.      Spot clean walls, partitions and entry doors.

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

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





                                       3
<PAGE>   86
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.

         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 ont 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

         A.      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.





                                       4
<PAGE>   87
IV.      ELEVATORS

         A.      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

         A.      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

         A.      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,
                 three hundred and sixty-five days per year.  The cost for
                 security entry cards shall be paid for by Tenant.

VII.     COMMON AREAS; LANDSCAPING

         A. Landlord shall:

                 (i)      keep the sidewalks, plazas and landscaped areas
adjoining the Building and any other horizontal structural surfaces adjoining
or forming any part of the Project (other than horizontal surfaces above the
ground floor) free of accumulation of snow and ice, direct, refuse, rubbish and
unlawful obstructions:

                 (ii)     keep the lobbies and the common and public areas of
the Building clean and presentable;

                 (iii)    care for and maintain the shrubbery, planting and
landscaping if any, on the plaza or plazas adjacent to the Building or other
public areas of the Property.





                                       5
<PAGE>   88
                                 FAIRFAX SQUARE

                                   SCHEDULE C

                            TENANT PLAN REQUIREMENTS

1.       Floor plan indicating location of partitions and doors (details
         required of partition and door types).

2.       Location of standard electrical convenience outlets
         and telephone outlets.

3.       Location and details of all special electrical outlets; e.g., Xerox,
         word processing, computer, including voltage, amperage, phase, and
         NEMA outlet configuration.

4.       Reflected ceiling plan showing layout of standard ceiling and lighting
         fixtures fully coordinated with mechanical.  Partitions to be shown
         with switches located indicating fixtures to be controlled.

5.       Locations and details of special ceiling conditions, lighting
         fixtures, speakers, exit signs, etc.

6.       Location and details of all plumbing fixtures, sinks drinking
         fountains, etc.

7.       Location and specifications of floorcovering, paint or     paneling
         with paint colors referenced to standard color system.

8.       Finish schedule plan indicating wallcovering, paint, or paneling with
         paint colors referenced to standard color system.

9.       Details and specifications of special millwork, glass partitions,
         rolling doors, blackboards, shelves, etc.

10.      Hardware schedule indicating door number keyed to plan, size, hardware
         required including butts, latchsets or locksets, closures, stops, and
         any special items such as thresholds, soundproofing, etc.  Keying
         schedule is required.

11.      Verified dimensions of all built-in equipment (file cabinets, kitchen
         equipment, plan files, etc.)

12.      Location and weights of storage files.

13.      Location and details of any special soundproofing
         requirements.
<PAGE>   89
14.      Location and details of special floor areas exceeding 80 pounds of
         live load per square foot.

15.      Location and details of special air conditioning requirements such as
         kitchens computer rooms, specifying the number of persons using the
         room and the BTU/Hr heat rejection into the room for kitchen
         equipment, computers, and other heat generating equipment.

16.      All specific dimensions shall be from established reference points.

17.      All drawings to be uniform size (30" x 42") and shall incorporate the
         standard project electrical and plumbing symbols and be at a scale of
         1/8" - 1' or larger.

18.      Drawing submittal shall include one sepia and three blue
         line prints of each drawing.

19.      Specifications.
<PAGE>   90
                                 FAIRFAX SQUARE

                                   SCHEDULE D

                             TENANT INTERIOR FINISH
                               BUILDING STANDARDS


Drywall:         5/8" gypsum board either side of 2-2-1/2' wide 25
                 gauge metal studs spaces 24" on center.  Partition is
                 to the underside of suspended ceiling tile.  Taped
                 and bedded at drywall joints, ready for painted
                 finish.

Doors:           Second floor corridor doors will match building standard only:
                 3'-0" x full height x 1-3/4" thick solid core doors with
                 premium grade, cherry hardwood veneer finish (both sides).

Frames:          Second floor corridor doors will match building standard only:
                 3'-0" full height extruded aluminum frame to accommodate 3'-0"
                 full height door.  Full length door silencer strips included.
                 Factory prefinished.

Hardware:        Building standard keyway will be used at all doors
                 and frames.

Lockset:         To be compatible with the Building's key system.

Ceiling Tile:    Flush mounted 2'x2'x 5/8" Minatone by Armstrong acoustical
                 ceiling tile and Donn Fineline exposed stylized narrow
                 suspended ceiling grid.

Lighting:        2'x4' parabolic fixtures with three 40-watt lamps.
                 Energy saving ballast with air handling (return air) 
                 capability.

Perimeter HVAC   Flush mounted 4'-0" long, combination supply and Diffusers:
                 return air slot diffusers, as required per design.

Interior         24" x 24" perforated supply diffusers with flex
Diffusers:       connections as required per design.

Thermostats:     One thermostat for each HVAC zone per floor.  Brushed metal
finish cover.

Sprinklers:      Concealed sprinkler head with white cover plate to match
ceiling finish.

Fire Extin-      Recessed with painted metal finish in color to 
quisher          match surrounding wall, equipped as required by 
Cabinet:         Code.
<PAGE>   91
Exit Lights:     Ceiling mounted exit sign.

Fire Alarm       Round 12" diameter white speaker mounted flush Speakers:
                 with ceiling tile, located as required by Code.

Smoke            White 6" diameter ion detector, as required by
Detectors:       Code.

Any deviation from the building standard items outlined herein must be
specifically approved in advance by Landlord.  Landlord's approval of any plans
shall be deemed to evidence Landlord's approval.
<PAGE>   92
                                 FAIRFAX SQUARE

                                   SCHEDULE E


                        FORM OF COMMENCEMENT DATE NOTICE

         THIS COMMENCEMENT DATE NOTICE is entered into this _______ day of
____________________ 199__, by FAIRFAX SQUARE ASSOCIATES II, a Virginia general
partnership ("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 Fairfax
Square ("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.

         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 _________________________ 199__.

         4.      The total GLA 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>   93
         IN WITNESS THEREOF, Landlord and Tenant have executed and sealed this
Commencement Date Notice as of the day and year first above-written.

                                           LANDLORD:
                                           
                                           FAIRFAX SQUARE ASSOCIATES II
                                           A VIRGINIA GENERAL PARTNERSHIP
                                           
                                           By: MAV Properties, Inc.
                                               its general partner
                                             
                                           
                                              By:                            
                                                  ---------------------------
                                                  Name:                    
                                                  Title:                    
                                           
                                           
                                           TENANT:
                                           
                                                                              
                                           -----------------------------------
                                           
                                           
                                           By:                                
                                               -------------------------------
                                               Name:
                                               Title:                        
                                                





                                      2
<PAGE>   94
                                 FAIRFAX SQUARE

                                   SCHEDULE F

                         CURRENT RULES AND REGULATIONS


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

         2.      The toilet rooms, water closets, sinks, faucets, plumbing and
other service apparatus of any kind shall not be used by the 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 the Tenant, or left by the
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 the 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 the
Landlord.  If the Landlord has installed or hereafter installs any shade, blind
or curtain in the Premises, the Tenant shall not remove it without first
obtaining the Landlord's written approval thereto.

         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 the Landlord.  Names on suite entrances shall be
provided by and only by the 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 the Landlord.  The
Tenant shall/will not erect any stand, booth or showcase or other article or
matter in or upon the Premises and/or the Building without first obtaining the
Landlord's written approval thereto.
<PAGE>   95
         5.      The Tenant shall not place any additional lock, security
devises, or graphics upon any door or wall within or outside the Premises or
elsewhere upon the Property without Landlord's approval, and shall surrender
all keys for all such locks at the end of the Term.  The Landlord shall provide
the Tenant with one set of keys to the Premises when the Tenant assumes
possession thereof.

         6.      The Tenant shall not do or permit to be done anything which
obstructs or interferes with the rights of any other tenant of the Property.
The Tenant shall not keep anywhere within the Property 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.

         7.      So that the Premises may be kept in a good state of
preservation and cleanliness, the Tenant shall, while in the possession of the
Premises, permit only the Landlord's employees and contractors to clean the
Premises unless prior thereto the Landlord otherwise consents in writing.  The
Landlord shall not be responsible to the Tenant for any damage done to any
furniture or other property of the Tenant or any other person caused by any of
the 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.  The
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 the Tenant desires to install signalling, telegraphic,
telephonic, protective alarm or other wires, apparatus or devices within the
Premises, the Landlord shall approve where and how they are to be installed
and, except as so directed, no installation, boring or cutting shall be
permitted.  The Landlord shall have the right (a) to prevent or interrupt the
transmission of excessive, dangerous current of electricity or otherwise into
or through the Building or the Premises, (b) to require the changing of wiring
connections or layout, at the Tenant's expense, to the extent that the Landlord
may reasonably deem necessary, (c) to require compliance with such reasonable
rules as the Landlord may establish relating thereto, and (d) in the event of
noncompliance with such requirements or rules, immediately to cut wiring to do
whatever else it considers necessary to remove the danger, annoyance or
electrical interference with apparatus





                                      2
<PAGE>   96
in any part of the Building.  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 the Tenant or other concern, if
any, operating or using it.

         9.      A main lobby directory will be provided by the Landlord at
Landlord's expense on which the Tenant's name may 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 the
Landlord, and only after Tenant gives notice thereof to the Landlord.  The
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.  The 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 Property 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, shall be borne by the Tenant as Additional Rent.

         11.     Without the 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, (c)
no switchboard or telephone wiring or equipment shall be placed anywhere other
than were designated by the Landlord, and (d) 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 the Landlord, unless approved in writing by
Landlord.

         12.     The 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, the Landlord shall have the right to bar or
limit access to the Building to protect the safety of occupants of the
Property, or any property within the Property.





                                      3
<PAGE>   97
         13.     The 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 the Landlord's reasonable judgment, are from
time to time needed for the safety, care, maintenance, operation and
cleanliness of the Building, or for the preservation of good order therein.
Upon the 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 the
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 as sleeping quarters
is strictly prohibited at all times.

         15.     The 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.  The Tenant shall comply with all reasonable
Rules and Regulations from time to time promulgated by the landlord with
respect to such system or their use.

         16.     Nothing in these Rules and Regulations shall give Tenant any
right or claim against the Landlord or any other person if the Landlord does
not enforce any of them against any other tenant or person (whether or not the
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 the Tenant or any other tenant or person.





                                      4
<PAGE>   98
                                 FAIRFAX SQUARE
                                   SCHEDULE G

                           AGREEMENT OF SUBORDINATION
                         NON-DISTURBANCE AND ATTORNMENT

           Attached to and made part of Lease dated December 8, 1995
                                    Between
                     FAIRFAX SQUARE ASSOCIATES II, Landlord
                                      and
                            NHP INCORPORATED, Tenant

         THIS AGREEMENT MADE AS OF THE 8th day of December, 1995, 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 NHP INCORPORATED, having its principle
office and post office address at 1225 Eye Street, N.W., Suite 601, Washington,
D.C. 20005 ("Tenant"),

                              W I T N E S S E T H:

         WHEREAS, FAIRFAX SQUARE ASSOCIATES II, a Virginia general partnership
("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 certain promissory
notes dated September 29, 1989, April 3, 1991, and February 18, 1992, secured
by a Deed of Trust of even date therewith, recorded in Book 7439 at Page 524,
in the Office of the Land Records, Fairfax County, Virginia, with amendments
recorded therein in Book 7781 at Page 547, and in Book 8025 at Page 1836 (as
amended, the "Deed of Trust") constituting a first lien upon the fee simple
estate of Landlord;

         WHEREAS under the terms of a certain lease dated December 8, 1995
("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.

         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:





<PAGE>   99
                 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, and

                 (b)      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.





                                      2
<PAGE>   100
         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:

                 (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,





                                      3
<PAGE>   101
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.

         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: 
                                        -------------------------------
                                     Name:                              
                                          ------------------------------
                                     Title:                             
                                           -----------------------------

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

         I HEREBY CERTIFY that on this ______ day of _______________ 1995,
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:

----------------------------





                                      4
<PAGE>   102
                               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.

                                  NHP INCORPORATED
                                  
                                  By:                         [SEAL]
                                     -------------------------------
                                  Name:                             
                                       -----------------------------
                                  Title:                            
                                        ----------------------------


CITY OF WASHINGTON                )
                                  )  To Wit:
DISTRICT OF COLUMBIA              )

         I HEREBY CERTIFY that on this _____ day of ___________ 1995, 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:

----------------------------





                                      5
<PAGE>   103
                                 FAIRFAX SQUARE

                                   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 FAIRFAX SQUARE ASSOCIATES II, 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





<PAGE>   104
         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,

         10.     norental 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>   105
                                 FAIRFAX SQUARE

                                   SCHEDULE I

                           BASE BUILDING DESCRIPTION


"Base Building" shall mean the condition of the Building with the following
improvements completed and substantially in accordance with Base Building
Plans:

1.       Complete building and site, including all public spaces, main building
         lobbies (first floor only), parking garage, and elevators;

2.       All central engineering systems (such as life safety, HVAC, electrical
         and plumbing), including those components required for vertical and
         horizontal distribution of the central engineering systems sized for
         normal office occupancy;

3.       Men's and ladies' bathroom facilities, with doors, lighting, fixtures,
         and finishes located on each office floor;

4.       Drinking fountains installed and operational;

5.       Fire extinguisher as required by county codes for an open floor plan,
         installed in stairways or core;

6.       Building fire stairs installed, and surrounding walls installed,
         taped, and floated;

7.       Building core installed, with walls installed, taped, and floated, and
         with elevator shaft doors and frames completed;

8.       Electrical and telephone distribution rooms installed on each level;

9.       Unfinished interior of exterior walls (with wall board portions of
         exterior walls taped and floated ready for surface treatments) and
         glass windows and frames installed;

10.      Broom-cleaned unfinished concrete floors; leveled and smoothed
         according to base building specifications;

11.      120-volt power for typical office receptacle use supplied to the
         electrical closet on each floor of the leased premises;

12.      Main heating, ventilating and air-conditioning duct work completed to
         the mixing boxes;





<PAGE>   106
13.      277/480 volt power for typical office fluorescent lighting supplied to
         the electrical closet on each floor of the leased premises;

14.      Sprinkler risers and main loop installed on each floor with capacity
         based on an open floor plan with runouts and heads as required by
         county codes.




                                               2
<PAGE>   107
                                     NHP


                                  [FIGURE 2]





<PAGE>   108
                                 FAIRFAX SQUARE
                                   SCHEDULE K

                         DUTIES OF CONSTRUCTION MANAGER

As Construction Manager, Landlord (or its affiliate) will:

PRECONSTRUCTION

    1.   Identify the responsibilities of each of the team members and 
         participate in the development and execution of these responsibilities.

    2.   Establish a schedule of critical dates and coordinate the 
         implementation of all tasks required for maintaining the
         project schedule.

    3.   Develop and maintain a project schedule for design and construction 
         based on the executed Lease.

    4.   Review the development of the Tenant's Plans and the Construction
         Documents for Lease compliance as well as adherence to Project schedule
         and budget.

    5.   Develop budget pricing and/or obtain pricing from contractors for
         construction costs.

    6.   Assist in pre-qualifying potential contractors for bid with Tenant.

    7.   Prepare bid analysis and make recommendations as to award of 
         contract(s).

    8.   Negotiate and administrate contracts for construction.

    9.   Assist General Contractor in obtaining building permit and special 
         permits  as may be required, except for permits to be obtained
         directly by contractors.

    10.  Develop and maintain job cost system for tracking Project costs.

    11.  Provide regular status reports as to the progress of the Project.


CONSTRUCTION

    1.   Provide administration of the contract(s) for construction.

    2.   Revise and refine Project budget and schedule to reflect contractor,
         Tenant and Tenant's architect input.
<PAGE>   109

    3.   Collect necessary documentation from contractor(s) prior to 
         commencement of construction, i.e., insurance certificates, bonds, etc.

    4.   Schedule, conduct, and record regular progress meetings with Tenant,
         contractor(s), and architect to review and resolve potential 
         outstanding items.

    5.   Monitor Project cost control system identifying variances between 
         actual and budget costs.  This system will also track Allowance 
         expenditures.

    6.   Identify costs recoverable from Tenant and Landlord under the Lease.
  
    7.   Obtain Tenant's approvals and issue Tenant notifications as they relate
         to the design and construction.

    8.   Review and approve in conjunction with the architect the contractor's
         Certificates for Payment.

    9.   Review request for changes, assist in negotiating contractor's 
         proposals, and submit recommendations as to their acceptability.

    10.  Assist the architect in the review, evaluation and documentation of
         claims.

    11.  Assist Tenant and architect in conducting inspections to determine
         whether the work is substantially complete.

    12.  Obtain the Certificates of Occupancy.

    13.  Assist the Tenant and Tenant's architect in the preparation of a
         punchlist of incomplete or unsatisfactory items and obtain from the
         contractor a schedule for their completion.  Assist in determining 
         value of punchlist items to be held as retainage.

    14.  Monitor completion of punchlist items and schedule final inspection.

    15.  Coordinate turnover of Premises and Storage Space to Tenant with
         delivery of warranties, keys, manuals, record drawings, balance 
         reports, etc.

    16.  Review final application for payment, and assure all required
         documentation has been submitted including final lien waivers.




                                     - 2 -
<PAGE>   110
                                 FAIRFAX SQUARE

                                   SCHEDULE L

                           PRIOR RIGHTS OF CURRENT TENANTS


As to both the Recurring ROFO and the Secondary ROFO, Informix Software, Inc.
has a right of first refusal on the sixth floor, and a right of first offer on
the balance of the Building.