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PURCHASE AND SALE AGREEMENT
   PURCHASE AND SALE
 Purchase and Sale
 Land
 Improvements
 Personal Property




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PURCHASE PRICE
   -2-




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DELIVERIES, INSPECTION, LOAN ASSUMPTION AND REPRESENTATIONS
 Delivery Obligations
 Inspection Period/Loan Assumption
   -3-




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Title and Survey
   -5-




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Purchasers Representations and Warranties
   -6-




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(1)
    
    is listed on the Specially Designated Nationals
and Blocked Persons List maintained by the Office of Foreign Asset
Control, Department of the Treasury (OFAC) pursuant to any enabling
legislation or other Executive Orders in respect thereof (the Order and
such other rules, regulations, legislation, or orders are collectively
called the Orders) and/or on any other list of terrorists or
terrorist organizations maintained pursuant to any of the rules and
regulations of OFAC or pursuant to any other applicable Orders (such
lists are collectively referred to as the Lists);(2)
    
    is owned or controlled by, nor acts for or on
behalf of, any Person on the Lists or any other Person who has been
determined by competent authority to be subject to the prohibitions
contained in the Orders;
   -7-




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Sellers Representations and Warranties
    Schedule 1
   Schedule 2
   -8-




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Schedule 3
    -9-




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3.5.5 Notwithstanding anything in this Agreement to the contrary, any liability of Seller to
Purchaser under or in respect of this Agreement after the Closing shall not exceed the Maximum
Amount
 Tenant Estoppel Certificates/ No Bankruptcy of Major Tenants
  -10-




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-11-




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ACCEPTANCE OF PROPERTY
 As Is
  -12-




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CLOSING
 Closing
 Possession
 Proration
  -13-




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New Letters of Credit
     -14-




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Closing Costs
 Sellers Obligations at the Closing
 Evidence of Authority
 Deed Exhibit B
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Assignment Exhibit C Exhibit
C-1
 FIRPTA Affidavit Exhibit D
 Tenant Notices Exhibit E
 Original Documents
 Transfer Tax Forms
 Rent Roll
 Escrow Direction
 Records and Files
 Purchasers Obligations at the Closing
 Purchase Price
 Evidence of Authority
 -16-




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Assignment
 Escrow Direction
 Transfer Tax Forms
 Property Management Agreement
 RISK OF LOSS
 Condemnation
 Casualty
 -17-




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Uniform Vendor and Purchaser Risk Act
 DEFAULT
 Breach by Seller
 Breach by Purchaser
 -18-




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FUTURE OPERATIONS
 Maintenance and Contracts
   Leasing
  -19-




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MISCELLANEOUS
 Notices
 If to Seller:
    
    c/o Sterling Advisors IV L.L.C.111 Great Neck RoadGreat Neck, NY 11021Attn: Richard A. WilponTelephone: (516) 504-2100Facsimile: (516) 504-2111with a copy to:
    
    Schiff Hardin LLP623 Fifth AvenueNew York, NY 10022Attn: Marina Rabinovich, Esq.Telephone: (212) 753-5000Facsimile: (212) 753-5044If to Purchaser:
    
    Columbia Equity Trust, Inc.1750 H Street, NWSuite 500Washington, DC 20006
 -20-




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Attn: Clint FischTelephone: (202) 303-3073Facsimile: (202) 303-3088with a copy to:
    
    Hunton & Williams LLP1900 K Street, NWSuite 1200Washington, DC 20006Attn: John M. RatinoTelephone: (202) 778-2221Facsimile: (202) 778-2201If to Escrow Agent:
    
    Fidelity National Title Insurance Company2 Park AvenueNew York, NY 10016Attn: Kenneth C. CohenTelephone: (212) 845-3135Facsimile: (646) 742-0733
  Real Estate Commissions
 Entire Agreement
 -21-




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Amendment
 Headings
 Time of Essence
 Successors and Assigns; Assignment
 Invalid Provision
 Attorneys Fees
 Multiple Counterparts
 -22-




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Exhibits
 Construction
 No Recordation
 Merger Provision
 Jury Waiver
 No Personal Liability of Officers, Directors, Etc. of Seller
 Choice of Law; Submission to Jurisdiction
 -23-




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Non-Solicitation of Employees
 Access
 ESCROW PROVISIONS
  -24-




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-25-




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SELLER:PATRICK HENRY ASSOCIATES L.P.By:
    
    SAP IV Patrick Henry NF GP L.L.C.,its sole general partnerBy: SAP IV manager, Inc.,its managerBy:
    
    /s/ Richard A. WilponIts:
    
    Senior Executive Vice
PresidentPURCHASER:COLUMBIA EQUITY TRUST, INC.,a Maryland corporationBy:
    
    /s/ Clinton FischIts:
    
    Director of
Acquisitions
  ESCROW AGENT:
    
    Fidelity National Title Insurance CompanyBy:Its:Date of Executionby Escrow Agent:_______, 2005
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SCHEDULE 1
 ITEMS TO BE DELIVERED  TO THE EXTENT IN SELLERS POSSESSION
 a)
    
    The last two years real estate tax bills;b)
    
    All utility invoices for the three (3) most current months (electric,
water, sewer and trash removal);c)
    
    The last three (3) years operating statements;d)
    
    Delinquencies Report (up to 90 days);e)
    
    Copies of the Leases (if too many, Purchaser may examine Leases at the
offices of the managing agent on prior notice);f)
    
    Copies of Operating Contracts;g)
    
    A rent roll (the Rent Roll) identifying all leases of space within the Property (the
Leases) current as of a date not earlier than thirty (30) days prior to the Effective Date;h)
    
    Existing Mortgage documents.




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SCHEDULE 2




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SCHEDULE 3




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EXHIBIT A
 LEGAL DESCRIPTION OF LAND




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EXHIBIT B
 DEED




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EXHIBIT C
 FORM OF ASSIGNMENT
 ASSIGNMENT AND ASSUMPTION OF OPERATING CONTRACTS, WARRANTIES AND LEASES
 Exhibit A




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,aBy:Its:Assignee:
    
    
    ,
    


aBy:Its:




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EXHIBIT C-1
 BILL OF SALE
 ,
    
  IN WITNESS WHEREOF




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EXHIBIT D
 FORM OF FIRPTA AFFIDAVIT
 TRANSFERORS CERTIFICATION OF NON-FOREIGN STATUS
 
  
  
 
 
    
  By:Its:




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EXHIBIT E
 FORM OF TENANT NOTICE
 
 
 
  
   Very truly
yours,SELLER:aBy:Its:




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EXHIBIT F
 TENANTS ESTOPPEL CERTIFICATE




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TENANT:




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TABLE OF CONTENTS
 PageSECTION 1.
    
    PURCHASE AND SALE
    
    
    11.1
    
    Purchase and Sale
    
    
    11.2
    
    Land
    
    
    11.3
    
    Improvements
    
    
    11.4
    
    Personal Property
    
    
    1SECTION 2.
    
    PURCHASE PRICE
    
    
    22.1
    
    
    
    
    2SECTION 3.
    
    DELIVERIES, INSPECTION AND REPRESENTATIONS
    
    
    23.1
    
    Delivery Obligations
    
    
    33.2
    
    Inspection Period
    
    
    33.3
    
    Title and Survey
    
    
    53.4
    
    Purchasers Representations and Warranties
    
    
    63.5
    
    Sellers Representations and Warranties
    
    
    83.6
    
    Tenant Estoppel Certificates
    
    
    10SECTION 4.
    
    ACCEPTANCE OF PROPERTY
    
    
    114.1
    
    As Is
    
    
    114.2
    
    
    
    
    12SECTION 5.
    
    CLOSING
    
    
    125.1
    
    Closing
    
    
    125.2
    
    Possession
    
    
    125.3
    
    Proration
    
    
    135.4
    
    Closing Costs
    
    
    145.5
    
    Sellers Obligations at the Closing
    
    
    155.6
    
    Purchasers Obligations at the Closing
    
    
    165.7
    
    Property Management Agreement
    
    
    16SECTION 6.
    
    RISK OF LOSS
    
    
    176.1
    
    Condemnation
    
    
    176.2
    
    Casualty
    
    
    176.3
    
    Uniform Vendor and Purchaser Risk Act
    
    
    18SECTION 7.
    
    DEFAULT
    
    
    18




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Page7.1
    
    Breach by Seller
    
    
    187.2
    
    Breach by Purchaser
    
    
    18SECTION 8.
    
    FUTURE OPERATIONS
    
    
    188.1
    
    Maintenance and Contracts
    
    
    188.2
    
    Leasing
    
    
    19SECTION 9.
    
    MISCELLANEOUS
    
    
    199.1
    
    Notices
    
    
    199.2
    
    Real Estate Commissions
    
    
    219.3
    
    Entire Agreement
    
    
    219.4
    
    Amendment
    
    
    219.5
    
    Headings
    
    
    219.6
    
    Time of Essence
    
    
    219.7
    
    Successors and Assigns; Assignment
    
    
    229.8
    
    Invalid Provision
    
    
    229.9
    
    Attorneys Fees
    
    
    229.10
    
    Multiple Counterparts
    
    
    229.11
    
    Exhibits
    
    
    229.12
    
    Construction
    
    
    229.13
    
    No Recordation
    
    
    229.14
    
    Merger Provision
    
    
    239.15
    
    Jury Waiver
    
    
    239.16
    
    No Personal Liability of Officers, Directors, Etc. of Seller
    
    
    239.17
    
    Choice of Law; Submission to Jurisdiction
    
    
    239.18
    
    Non-Solicitation of Employees
    
    
    239.19
    
    Access
    
    
    23SECTION 10.
    
    ESCROW PROVISIONS
    
    
    2410.1
    
    
    
    
    2410.2
    
    
    
    
    2410.3
    
    
    
    
    2410.4
    
    
    
    
    25
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PURCHASE AND SALE AGREEMENT