Document:

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             Exhibit 10.1 - Exchange Agreement (Virginia Properties)

                               EXCHANGE AGREEMENT

                                     between

                 PRENTISS PROPERTIES ACQUISITION PARTNERS, L.P.,
                         a Delaware limited partnership

                                  ("Prentiss")

                                       and

                           BRANDYWINE GRANDE B, L.P.,
                         a Delaware limited partnership

                                  ("Grande B")

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                                TABLE OF CONTENTS
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                                                                                                               Page

<S>                                                                                                              <C>
ARTICLE I. DEFINITIONS............................................................................................1
   1.1   Definitions..............................................................................................1
ARTICLE II. EXCHANGE OF PROPERTY; DEPOSIT; EXCHANGE VALUE; STUDY PERIOD...........................................7
   2.1   Exchange Property........................................................................................7
   2.2   Exchange Value...........................................................................................7
   2.3   Deposit..................................................................................................7
   2.4   Study Period.............................................................................................7
ARTICLE III. GRANDE B'S REPRESENTATIONS AND WARRANTIES...........................................................12
   3.1   Organization and Power..................................................................................12
   3.2   Authorization, Execution and Disclosure.................................................................12
   3.3   Non-contravention.......................................................................................12
   3.4   No Special Taxes........................................................................................13
   3.5   Compliance with Existing Laws and Restrictive Covenants.................................................13
   3.6   Personal Property.......................................................................................13
   3.7   Operating Agreements....................................................................................13
   3.8   Condemnation Proceedings; Roadways......................................................................13
   3.9   Actions or Proceedings..................................................................................13
   3.10  Bankruptcy..............................................................................................14
   3.11  Hazardous Substances....................................................................................14
   3.12  Parties in Possession...................................................................................14
   3.13  Leases..................................................................................................14
   3.14  Leased Property.........................................................................................15
   3.15  No Unpaid Charges.......................................................................................15
   3.16  Condition of Improvements...............................................................................15
   3.17  Access..................................................................................................15
   3.18  No Commitments..........................................................................................15
   3.19  Grande B Is Not a "Foreign Person"......................................................................16
   3.20  Leasing Commissions.....................................................................................16
   3.21  Other Agreements........................................................................................16
   3.22  Existing Secured Indebtedness...........................................................................16
   3.23  Employment on "At-Will" Basis...........................................................................16
   3.24  LIMITATIONS ON REPRESENTATIONS AND WARRANTIES...........................................................16
ARTICLE IV. PRENTISS' REPRESENTATIONS AND WARRANTIES.............................................................18
   4.1   Organization and Power..................................................................................18
   4.2   Non-contravention.......................................................................................18
   4.3   Litigation..............................................................................................18
   4.4   Bankruptcy..............................................................................................18
   4.5   Authorization, Execution and Disclosure.................................................................18
ARTICLE V. CONDITIONS PRECEDENT..................................................................................18
   5.1   As to Prentiss' Obligations.............................................................................18
   5.2   As to Grande B's Obligations............................................................................20
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<S>                                                                                                             <C>
ARTICLE VI. COVENANTS OF GRANDE B................................................................................20
   6.1   Operating Agreements....................................................................................20
   6.2   Warranties and Guaranties...............................................................................21
   6.3   Insurance...............................................................................................21
   6.4   Operation of Property Prior to Closing..................................................................21
   6.5   No Marketing............................................................................................22
   6.6   Leased Property.........................................................................................22
ARTICLE VII. CLOSING.............................................................................................23
   7.1   Closing.................................................................................................23
   7.2   Grande B's Deliveries...................................................................................23
   7.3   Prentiss' Deliveries....................................................................................25
   7.4   Mutual Deliveries.......................................................................................26
   7.5   Closing Costs...........................................................................................26
   7.6   Revenue and Expense Allocations.........................................................................26
   7.7   Delinquent Rents........................................................................................27
   7.8   Costs Associated with Certain Leasing Activities........................................................28
ARTICLE VIII. GENERAL PROVISIONS.................................................................................28
   8.1   Condemnation............................................................................................28
   8.2   Risk of Loss............................................................................................29
   8.3   Broker..................................................................................................29
   8.4   Bulk Sale...............................................................................................29
ARTICLE IX. LIABILITY OF PRENTISS; INDEMNIFICATION BY GRANDE B; DEFAULT; TERMINATION RIGHTS......................30
   9.1   Liability of Prentiss...................................................................................30
   9.2   Indemnification by Grande B.............................................................................30
   9.3   Default by Grande B/Failure of Conditions Precedent.....................................................30
   9.4   Indemnification by Prentiss.............................................................................31
   9.5   Default by Prentiss/Failure of Conditions Precedent.....................................................32
   9.6   Costs and Attorneys' Fees...............................................................................32
   9.7   Limitation of Liability.................................................................................32
ARTICLE X. MISCELLANEOUS PROVISIONS..............................................................................32
   10.1  Completeness; Modification..............................................................................32
   10.2  Assignments.............................................................................................32
   10.3  Successors and Assigns..................................................................................33
   10.4  Days....................................................................................................33
   10.5  Governing Law...........................................................................................33
   10.6  Counterparts............................................................................................33
   10.7  Severability............................................................................................33
   10.8  Notices.................................................................................................33
   10.9  Escrow Agent............................................................................................34
   10.10 Incorporation by Reference..............................................................................35
   10.11 Survival................................................................................................35
   10.12 Further Assurances......................................................................................35
   10.13 No Partnership..........................................................................................35
   10.14 Time of Essence.........................................................................................35
   10.15 Signatory Exculpation...................................................................................35
   10.16 Rules of Construction...................................................................................35
   10.17 Like-Kind Exchange......................................................................................36
   10.18 SEC Reporting (8-K) Requirements........................................................................36
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   10.16 Rules of Construction................................................................................35
   10.17 Like-Kind Exchange...................................................................................36
   10.18 SEC Reporting (8-K) Requirements.....................................................................36
</TABLE>

EXHIBITS
Exhibit A -       Land
Exhibit B -       Exchange Property
Exhibit C -       Tenant's Estoppel Certificate
Exhibit D -       Excluded Tangible Personal Property

SCHEDULES
Schedule 3.7      Assumed Operating Agreements
Schedule 3.13     Rent Roll and Accounts Receivable Report
Schedule 3.20     Outstanding Leasing Commissions
Schedule 6.4(g)   Approved New Leases

                                      iii

<PAGE>

                               EXCHANGE AGREEMENT

         THIS EXCHANGE AGREEMENT (this "Agreement") is made as of this 14th day
of March, 2001, between PRENTISS PROPERTIES ACQUISITION PARTNERS, L.P., a
Delaware limited partnership and/or assigns (collectively, "Prentiss"), and
BRANDYWINE GRANDE B, L.P., a Delaware limited partnership ("Grande B").

                             R E C I T A T I O N S:

         A. Grande B is the owner of certain real properties located in Fairfax
County, Commonwealth of Virginia, as more particularly identified on Exhibit A,
attached hereto and made a part hereof for all purposes.

         B. Prentiss is desirous of acquiring such property from Grande B and
Grande B is desirous of conveying such property to Prentiss, upon the terms and
conditions hereinafter set forth, in exchange for the conveyance of certain
property by Prentiss to Grande B in accordance with an Exchange Agreement of
even date herewith between Grande B and Prentiss (the "Second Exchange
Agreement").

         NOW, THEREFORE, in consideration of the foregoing premises and in
consideration of the mutual covenants, promises and undertakings of the parties
hereinafter set forth, and for other good and valuable consideration, the
receipt and sufficiency of which is hereby acknowledged by the parties, it is
agreed:

                                   ARTICLE I.
                                   DEFINITIONS

1.1      Definitions.  The following terms shall have the indicated meanings:

                  "Act of Bankruptcy" shall mean if a party hereto or any
general partner thereof shall (a) apply for or consent to the appointment of, or
the taking of possession by, a receiver, custodian, trustee or liquidator of
itself or of all or a substantial part of its property, (b) admit in writing its
inability to pay its debts as they become due, (c) make a general assignment for
the benefit of its creditors, (d) file a voluntary petition or commence a
voluntary case or proceeding under the Federal Bankruptcy Code (as now or
hereafter in effect), (e) be adjudicated a bankrupt or insolvent, (f) file a
petition seeking to take advantage of any other law relating to bankruptcy,
insolvency, reorganization, winding-up or composition or adjustment of debts,
(g) fail to controvert in a timely and appropriate manner, or acquiesce in
writing to, any petition filed against it in an involuntary case or proceeding
under the Federal Bankruptcy Code (as now or hereafter in effect), or (h) take
any corporate or partnership action for the purpose of effecting any of the
foregoing; or if a proceeding or case shall be commenced, without the
application or consent of a party hereto or any general partner thereof, in any
court of competent jurisdiction seeking (1) the liquidation, reorganization,
dissolution or winding-up, or the composition or readjustment of debts, of such
party or general partner, (2) the appointment of a receiver, custodian, trustee
or liquidator for such party or general partner or all or any substantial part
of its assets, or (3) other similar relief under any law relating to bankruptcy,
insolvency, reorganization, winding-up or composition or adjustment of debts,
and such proceeding or case shall continue undismissed for a period of ninety
(90) consecutive days; or an order (including an order for relief entered in an
involuntary case under the Federal Bankruptcy Code, as now or hereafter in
effect) judgment or decree approving or ordering any of the foregoing shall be
entered and continue unstayed and in effect, for a period of ninety (90)
consecutive days.

                                       1
<PAGE>

                  "Applicable Laws" shall mean any applicable building, zoning,
subdivision, environmental, health, safety or other governmental laws, statutes,
ordinances, resolutions, rules, codes, regulations, orders or determinations of
any Governmental Authority or of any insurance boards of underwriters (or other
body exercising similar functions), or any restrictive covenants or deed
restrictions affecting the Property or the ownership, operation, use,
maintenance or condition thereof.

                  "Assignment and Assumption Agreement" shall mean one or more
assignment and assumption agreements whereby, subject to the allocation
provisions in Section 7.8 hereof, (a) Grande B (1) assigns and Prentiss assumes
the Assumed Operating Agreements, (2) assigns all of Grande B's right, title and
interest in and to the Intangible Personal Property, to the extent assignable,
and (3) indemnifies, defends and holds Prentiss and its agents, employees,
officers, directors, shareholders and contractors harmless with respect to all
defaults, liabilities, claims, costs and expenses (including, without
limitation, reasonable attorneys' fees) relating to acts or omissions accruing
under such Assumed Operating Agreements before the Closing Date; and (b)
Prentiss indemnifies, defends and holds Grande B harmless with respect to all
defaults, liabilities, claims, costs and expenses (including, without
limitation, reasonable attorneys' fees) relating to acts or omissions accruing
under such Assumed Operating Agreements after the Closing Date.

                  "Assignment of Leases" shall mean the assignment agreement, in
recordable form, whereby, subject to the allocation provisions in Section 7.8
hereof, (a) Grande B (1) assigns and Prentiss assumes all of Grande B's right,
title and interest in and to the Leases, and (2) indemnifies, defends and holds
Prentiss and its agents, employees, officers, directors, shareholders and
contractors harmless with respect to all defaults, liabilities, claims, costs
and expenses (including, without limitation, reasonable attorneys' fees)
relating to acts or omissions accruing under such Leases before the Closing
Date; and (b) Prentiss indemnifies, defends and holds Grande B harmless with
respect to all defaults, liabilities, claims, costs and expenses (including,
without limitation, reasonable attorneys' fees) relating to acts or omissions
accruing under such Leases after the Closing Date.

                  "Assumed Operating Agreements" shall mean the Operating
Agreements described in Section 3.7 hereto which are to be assigned pursuant to
the Assignment and Assumption Agreement.

                  "Authorizations" shall mean all licenses, permits and
approvals required by any governmental or quasi-governmental agency, body,
department, commission, board, bureau, instrumentality or officer, any owners
association created pursuant to deed restrictions affecting the Real Property or
otherwise appropriate with respect to the construction, ownership, operation,
leasing, maintenance, or use of the Property or any part thereof.

                                       2
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                  "Bill of Sale - Personal Property" shall mean one or more
bills of sale conveying title to the Tangible Personal Property and the
Intangible Personal Property from Grande B to Prentiss.

                  "Brandywine OP" shall mean Brandywine Operating Partnership,
L.P., a Delaware limited partnership, which is the owner, as a limited partner,
of a ninety-nine percent (99%) limited partnership interest in Grande B.

                  "Closing" shall mean the Closing of the conveyance of the
Property pursuant to this Agreement and shall be deemed to occur on the Closing
Date.

                  "Closing Date" shall mean the date on which the Closing
occurs.

                  "Closing Documents" shall mean the documents defined as such
in Section 7.1 hereof.

                  "Deeds" shall mean those certain special warranty deeds
conveying title to each of the Parcels and subject only to Permitted Title
Exceptions affecting each such Parcel. If there is any difference between the
description of any portion of the Land constituting a Parcel as shown on Exhibit
A attached hereto and the description of the applicable Parcel as shown on the
Survey, the description of the applicable Parcel to be contained in the
applicable Deed and the description of such Parcel set forth in the Title
Commitment shall conform to the description shown on the Survey.

                  "Deposit" shall mean all amounts deposited from time to time
with Escrow Agent by Prentiss pursuant to Section 2.3 hereof, plus all interest
or other earnings that may accrue thereon. All cash Deposits shall be invested
by Escrow Agent in a commercial bank or banks acceptable to Prentiss at money
market rates, or in such other investments as shall be approved in writing by
Grande B and Prentiss. The Deposit shall be held and disbursed by Escrow Agent
in strict accordance with the terms and provisions of this Agreement.

                  "Environmental Damages" shall mean all third-party claims,
judgments, damages, losses, penalties, fines, liabilities (including, without
limitation, punitive damages and strict liability), encumbrances, liens, costs
and expenses of investigation and defense of any claim, whether or not such is
ultimately defeated, and of any settlement or judgment, of whatever kind or
nature, contingent or otherwise, matured or unmatured, including, without
limitation, attorneys' fees and disbursements and consultants' fees, any of
which arise as a result of the existence of Hazardous Materials upon, about or
beneath the Property or migrating or threatening to migrate from the Property,
or as a result of the existence of a violation of Environmental Requirements
pertaining to the Property.

                  "Environmental Requirements" shall mean (i) all applicable
statutes, regulations, rules, policies, ordinances, codes, licenses, permits,
orders, approvals, plans, authorizations, and similar items, of all Governmental
Authorities, and (ii) all judicial, administrative and regulatory decrees,
judgments and orders, in each case of (i) and (ii) relating to the protection of
human health or the environment from Hazardous Materials and health and safety
of employees or the public from Hazardous Materials, including, without
limitation, all requirements thereof pertaining to reporting, licensing,
permitting, investigation and remediation of emissions, discharges, releases or
threatened releases of Hazardous Materials into the air, surface water,
groundwater or land, or relating to the manufacture, processing, distribution,
use, treatment, storage, disposal, transport or handling of Hazardous Materials.

                                       3
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                  "Escrow Agent" shall mean Chicago Title Insurance Company,
whose address is 2001 Bryan Street, Suite 1700, Dallas, Texas 75201, Attention:
Ellen Schwab.

                  "Exchange Property" shall mean the real property and
improvements thereon to be conveyed by Prentiss to Grande B pursuant to the
Second Exchange Agreement, which real property is described on Exhibit B hereto.

                  "Exchange Value" shall mean $107,200,000.00 to be allocated
among the Parcels as provided in Section 2.2 hereof.

                  "FIRPTA Certificate" shall mean the affidavit of Grande B
under Section 1445 of the Internal Revenue Code, as amended, certifying that
Grande B is not a foreign corporation, foreign partnership, foreign trust,
foreign estate or foreign person (as those terms are defined in the Internal
Revenue Code and regulations promulgated thereunder), in form and substance
satisfactory to Prentiss.

                  "Governmental Authority" shall mean any federal, state,
county, municipal or other government or any governmental or quasi-governmental
agency, department, commission, board, bureau, officer or instrumentality,
foreign or domestic, or any of them.

                  "Grande B's Organizational Documents" shall mean the
organizational documents and all amendments thereto of Grande B and Brandywine
OP.

                  "Hazardous Materials" shall mean any chemical substance: (i)
which is or becomes defined as a "hazardous substance," "hazardous waste,"
"hazardous material," "pollutant," "contaminant," or "toxic," "explosive,"
"corrosive," "flammable," "infectious," "radioactive," "carcinogenic," or
"mutagenic" material under any law, regulation, rule, order, or other authority
of the federal, state or local governments, or any agency, department,
commission, board, or instrumentality thereof, regarding the protection of human
health or the environment from such chemical substances including, but not
limited to, the following federal laws and their amendments, analogous state and
local laws, and any regulations promulgated thereunder: the Clean Air Act, the
Clean Water Act, the Oil Pollution Control Act, the Comprehensive Environmental
Response, Compensation, and Liability Act of 1986, the Emergency Planning and
Community Right to Know Act, the Solid Waste Disposal Act, the Resource
Conservation and Recovery Act, the Safe Drinking Water Act, the Federal
Insecticide, Fungicide and Rodenticide Act, and the Toxic Substances Control
Act, including, without limitation, asbestos and gasoline and other petroleum
products (including crude oil or any fraction thereof); (ii) without limitation,
which contains gasoline, diesel fuel or other petroleum hydrocarbons; (iii)
without limitation, which contains asbestos-containing materials or urea
formaldehyde foam insulation; or (iv) without limitation, radon gas; provided,
however, the term "Hazardous Materials" shall not include de minimis quantities
of substances of kinds and in amounts ordinarily and customarily used or stored
in properties similar to the Property for the purposes of cleaning or other
maintenance or operations and otherwise in compliance with Environmental
Requirements.

                                       4
<PAGE>

                  "Improvements" shall mean all buildings, improvements,
fixtures and other items of real estate located on the various Parcels of Real
Estate which constitute the Land.

                  "Insurance Policies" shall mean all policies of insurance
maintained by or on behalf of Grande B pertaining to the Property, its
operation, or any part thereof.

                  "Intangible Personal Property" shall mean all intangible
personal property owned or possessed by Grande B and used in connection with the
ownership, operation, leasing, occupancy or maintenance of the Property,
including, without limitation, (1) Grande B's exclusive right to use any trade
names associated with the Property and all variations thereof (other than
variants of Brandywine's legal name, all rights to which shall be retained by
Grande B), (2) the Authorizations, (3) escrow accounts (subject to the
provisions of Section 7.6 hereof), utility and development rights and
privileges, general intangibles, business records, plans and specifications
pertaining to the Real Property and the Personal Property, and (4) any unpaid
award for taking by condemnation or any damage to the Land by reason of a change
of grade or location of or access to any street or highway.

                  "Land" shall mean those certain parcels of real estate lying
and being in Fairfax County, Commonwealth of Virginia, as more particularly
described on Exhibit A attached hereto, together with all easements, rights,
privileges, remainders, reversions and appurtenances thereunto belonging or in
any way appertaining, and all of the estate, right, title, interest, claim or
demand whatsoever of Grande B therein, in the streets and ways adjacent thereto
and in the beds thereof, either at law or in equity, in possession or
expectancy, now or hereafter acquired.

                  "Leased Property" shall mean all leased items of personal
property.

                  "Leases" shall mean all leases, tenancies and other rights of
occupancy or use for any portion of the Real Property and leasehold estate,
together with any and all amendments thereto.

                  "Operating Agreements" shall mean all management, service,
supply and maintenance contracts, if any, in effect with respect to the Property
and all other contracts (other than the Leases) that affect the Property or are
otherwise related to the construction, ownership, operation, occupancy or
maintenance of the Property.

                  "Owner's Title Policy" shall mean an owner's policy of title
insurance issued to Prentiss by the Title Company, pursuant to which the Title
Company insures Prentiss' ownership of fee simple title to the Real Property
subject only to Permitted Title Exceptions. The Owner's Title Policy shall
insure Prentiss in the amount of $107,200,000.00 and shall be acceptable in form
and substance to Prentiss. Prentiss may require such deletions of standard
exceptions and such title endorsements as are legally available and customarily
required by institutional investors purchasing property comparable to the
Property in the State where the Property is situated. The description of the
Land in the Owner's Title Policy shall be by courses and distances or by
reference to a legal, subdivided lot and shall be identical to the description
shown on the Survey.

                                       5
<PAGE>

                  "Parcel" shall mean each individual tract of the Real Property
described on Exhibit A hereto.

                  "Permitted Title Exceptions" shall mean those exceptions to
title to the Real Property that are satisfactory to Prentiss as determined
pursuant to Section 2.4(d) hereof.

                  "Personal Property" shall mean collectively the Tangible
Personal Property and the Intangible Personal Property.

                  "Prentiss' Objections" shall mean the objections defined as
such in Section 2.4(d) hereof.

                  "Prentiss' Organizational Documents" shall mean the
organizational documents and all amendments thereto of Prentiss.

                  "Property" shall mean collectively the Real Property and the
Personal Property.

                  "Real Property" shall mean the Land and the Improvements.

                  "Rent Roll" shall have the meaning ascribed to such term in
Section 2.4(b)(2) of this Agreement.

                  "Second Exchange Agreement" shall have the meaning ascribed to
such term in Recital B above.

                  "Study Period" shall mean the period commencing on the date
this Agreement has been fully executed and delivered by all parties hereto, and
continuing through February 16, 2001. Except as expressly noted herein to the
contrary, time periods herein referred to shall mean the time periods as in
effect, from time to time, at Dallas, Texas.

                  "Submission Matters" shall mean all items Grande B is required
to deliver to Prentiss pursuant to Section 2.4(b) hereof.

                  "Survey" shall mean the survey defined as such in and prepared
pursuant to Section 2.4(d) hereof.

                  "Tangible Personal Property" shall mean the items of tangible
personal property consisting of all furniture, fixtures, equipment, machinery
and other personal property of every kind and nature located on or used or
useful in the ownership and operation of the Property and owned by Grande B,
including, without limitation, Grande B's interest as lessee with respect to any
such Tangible Personal Property, other than (a) the items of personal property
identified on Exhibit D hereto, and (b) the Leased Property, the title to which
personal property described in clauses (a) and (b) is not being transferred
pursuant to this Agreement.

                  "Title Commitment" shall mean the title commitment and
exception documents defined as such in Section 2.4(d) hereof.

                                       6
<PAGE>

                  "Title Company" shall mean Chicago Title Insurance Company or
other title insurance underwriter selected by Prentiss.

                  "UCC Reports" shall mean the reports defined as such in
Section 2.4(d) hereof.

                  "Utilities" shall mean public sanitary and storm sewers,
natural gas (if any), telephone, public water facilities, electrical facilities
and all other utility facilities and services (if any) necessary or appropriate
for the operation and occupancy of the Property as an office building.

                  "Warranties and Guaranties" shall mean all warranties and
guaranties relating to the Improvements, or the Tangible Personal Property or
any part thereof.

                                  ARTICLE II.
           EXCHANGE OF PROPERTY; DEPOSIT; EXCHANGE VALUE; STUDY PERIOD

         2.1 Exchange Property. On the Closing Date, Grande B agrees to transfer
the Property to Prentiss in accordance with and subject to the other terms and
conditions set forth herein, in exchange for the transfer of the Exchange
Property by Prentiss to Grande B in accordance with and subject to the terms and
conditions of the Second Exchange Agreement.

         2.2 Exchange Value. Prentiss and Grande B hereby agree that the
Exchange Value of the Property is $107,200,000.00, to be allocated among the
Parcels in a manner to be agreed upon by Prentiss and Grande B on or before the
Closing Date.

         2.3 Deposit. Within three (3) days after the execution hereof by both
Grande B and Prentiss and as a condition precedent to the effectiveness of this
Agreement, Prentiss shall deliver to Escrow Agent a wire transfer or check (a)
in the sum of Fifty Dollars ($50.00) (the "Independent Consideration"), payable
to the order of Grande B representing the Independent Consideration for Grande
B's execution of this Agreement and agreement to provide Prentiss with the Study
Period (which check or the proceeds of which wire transfer shall thereafter be
delivered by Escrow Agent to Grande B), and (b) in the sum of $700,000.00 (the
proceeds of which wire transfer or check Escrow Agent shall deposit and invest
in an interest bearing account at a financial institution acceptable to Prentiss
or as otherwise agreed to in writing by Grande B and Prentiss). The proceeds of
the wire transfer or check are referred to herein as the "Deposit" and Escrow
Agent shall hold and invest the Deposit pursuant to the terms, conditions and
provisions of this Agreement. All accrued interest on the Deposit shall become
part of the Deposit. The Deposit (regardless of whether it is the proceeds of a
wire transfer or check) shall be either (a) returned to Prentiss pursuant
hereto, or (b) paid to Grande B pursuant hereto. For purposes of reporting
earned interest with respect to the Deposit, Prentiss' Federal Tax
Identification Number is 75-2672997, and Grande B's Federal Tax Identification
Number is 23-2977952.

         2.4 Study Period.

             (a) Prentiss and its` agents, contractors and duly authorized
representatives shall have the right, until 5:00 p.m., Dallas, Texas time on the
last day of the Study Period, and thereafter unless, as provided below, Prentiss
notifies Grande B in writing prior to the expiration of the Study Period that

                                       7
<PAGE>

Prentiss has elected to terminate this Agreement, to enter upon the Real
Property and to perform, at Prentiss' expense, such economic, surveying,
engineering, topographic, environmental, marketing and other tests, studies and
investigations as Prentiss may deem appropriate. If such tests, studies and
investigations do not warrant, in Prentiss' sole, absolute and unreviewable
discretion, the acquisition of the Property for the purposes contemplated by
Prentiss, then Prentiss may elect not to proceed with this transaction and shall
notify Grande B and Escrow Agent, in writing prior to the expiration of the
Study Period, that Prentiss has elected to terminate this Agreement, in which
event this Agreement automatically shall terminate, the Deposit shall be
promptly returned to Prentiss and Prentiss and Grande B shall be released from
all further liability or obligation hereunder except those which expressly
survive a termination of this Agreement. If Prentiss does not so notify Grande B
of its determination to terminate this Agreement prior to the expiration of the
Study Period, then Prentiss shall be deemed to have waived its right to
terminate this Agreement pursuant to this Section 2.4.

             (b) Grande B has delivered or made available at the Property the
following to Prentiss:

                 (1) Copies of all Leases in effect as of the date of this
     Agreement, together with, to the extent in Grande B's possession or
     reasonably available to Grande B, copies of all correspondence received
     from or sent to tenants of the Property.

                 (2) a Rent Roll (herein so called) certificate (with current
     rent roll and accounts receivable report attached) for the Property
     containing the following information with respect to each Lease: (i) a
     description of the space occupied thereby (including square feet, type of
     space, floor and tenant's pro rata share of common elements), (ii) tenant's
     name, (iii) the commencement date and expiration date thereof, (iv) the
     rental rate per square foot, (v) the amount of fixed monthly rental, (vi)
     the amount of any percentage or other additional rental and/or common area
     maintenance, tax, insurance and operating expenses and any other charges
     payable thereunder and, if applicable, the base year used in each Lease,
     (vii) the amount of any prepayment in rental, (viii) the amount of the
     security deposit or any other deposit thereunder, (ix) any free rent,
     concessions, rebates, refunds, refurbishment allowances or other
     inducements which any tenant will be entitled to receive after December 31,
     2000 (including, without limitation, any of the foregoing that may be
     payable in connection with renewals, extensions or expansions expressly
     contemplated in any of such Leases), (x) any options provided thereunder,
     including, without limitation, any renewal options, expansion options,
     purchase options and rights of first refusal and (xi) delinquency in rental
     or other charges set forth in the attached accounts receivable report.

                 (3) To the extent in Grande B's possession or reasonably
     available to Grande B, copies of all Authorizations including, without
     limitation, all certificates of occupancy, permits, authorizations,
     approvals (including drawings and enacting ordinances, if any), special
     exceptions, variances, and licenses issued by Governmental Authorities
     having jurisdiction over the Property and copies of all certificates issued
     by the local board of fire underwriters (or other body exercising similar
     functions) relating to the Property. For the purpose of this Agreement any
     Submission Matters in the possession of Grande B or Grande B's management
     company shall be deemed to be "reasonably available to Grande B."

                                       8
<PAGE>

                 (4) To the extent in Grande B's possession or reasonably
     available to Grande B: (X) operating statements showing all income and
     expenses, profits and losses of the Property for the previous three (3)
     calendar years, which shall reflect (i) ad valorem taxes for the City,
     County and State or Commonwealth; (ii) expenses incurred for such period
     for water, electricity, natural gas and other utility charges; (iii) other
     operating expenses; (iv) total rents collected from tenants for such
     periods; and (v) other revenue collected and nature of such revenue; and
     (Y) financial statements for the Property for the previous three (3)
     calendar years, including, if available, the reports of accountants
     thereon.

                 (5) Operating and capital expenditure budgets for the current
     calendar year and, to the extent in Grande B's possession or reasonably
     available to Grande B, for the previous three (3) calendar years.

                 (6) All existing surveys and title policies for the Property
     that are reasonably available to Grande B.

                 (7) A complete list of all Assumed Operating Agreements and
     leasing commission agreements in effect as of the date of this Agreement
     and complete copies of all such Assumed Operating Agreements and leasing
     commission agreements.

                 (8) A complete list of all Tangible Personal Property.

                 (9) To the extent in Grande B's possession or reasonably
     available to Grande B, any information in Grande B's possession or
     reasonably available to Grande B regarding current renditions or
     assessments on the Property or notices relative to change in valuation for
     ad valorem taxes.

                 (10) A complete list of all Warranties and Guaranties in effect
     as of the date of this Agreement and complete copies of all such Warranties
     and Guaranties.

                 (11) Copies of all soil tests, structural engineering tests,
     inspection reports, asbestos surveys, masonry tests, percolation tests,
     water, oil, gas, mineral, radon, formaldehyde, PCB or other environmental
     tests, audits or reports, market studies and site plans related to the
     Property in Grande B's possession or reasonably available to Grande B,
     together with copies of any and all correspondence, reports and other
     written documentation regarding the environmental aspects of the property
     or any toxic substances or equipment affecting or related to the Property.

                 (12) If in Grande B's possession or reasonably available to
     Grande B, copies of complete sets of all architectural, mechanical,
     structural and/or electrical plans and specifications used in connection
     with the construction of or alterations or repairs to the Property.

                                       9
<PAGE>

                 (13) If in Grande B's possession or reasonably available to
     Grande B, copies of as-built plans and specifications for the Property.

                 (14) Parking, structural, mechanical or other engineering
     reports or studies related to the Property, if any, in Grande B's
     possession or reasonably available to Grande B.

                 (15) To the extent in the possession of Grande B or any
     affiliate of Grande B or Grande B's property manager, copies of credit
     reports and financial information on all tenants in possession of any of
     the Property and of any guarantors of such tenants' obligations.

                 (16) Copies of all approvals from any owners associations
     having jurisdiction over the Real Property and copies of all correspondence
     from any such owners association.

                 (17) Copies of all Insurance Policies in effect, together with
     the name and telephone number of either a contact person at each insurance
     company or the insurance broker involved with the issuance of the Insurance
     Policies.

         During the Study Period and thereafter until the Closing, Grande B
shall make available to Prentiss, copies of all materials, correspondence,
books, records, financial statements, operating statements and any and all other
materials or information relating to the Property which come into Grande B's
possession or control or are otherwise reasonably available to Grande B from and
after the date on which the Submission Matters were delivered to Prentiss.

         Notwithstanding anything herein to the contrary, although Prentiss has
not received all of the deliveries described in this Section 2.4(b), Prentiss
has completed its feasibility study pursuant to Section 2.4(a) but reserves the
right to require, and Grande B hereby agrees to deliver, to the extent available
to it, any item described in Section 2.4(b) not previously delivered at any time
during the period expiring six (6) months after the Closing Date, which
agreement shall survive the Closing Date for such six (6) month period.

             (c) Prentiss shall indemnify and defend Grande B against any loss,
damage or claim for personal injury or property damage (including reasonable
attorney's fees) arising from the entry upon the Property pursuant to this
Section 2.4 by Prentiss or any agents, contractors or employees of Prentiss.
Prentiss, at its own expense, shall restore any damage to the Property caused by
any of the tests or studies made by Prentiss. This provision shall survive any
termination of this Agreement and a closing of the transaction contemplated
hereby.

             (d) On or before 5:00 p.m. Dallas, Texas time on the date that is
five (5) days after the date of this Agreement, Grande B shall deliver to
Prentiss, at Grande B's sole cost and expense, the most recent Surveys of the
Land and the Improvements for all of the Land and Improvements which constitute
the Property, which are in the possession of Grande B. Such Surveys shall have
been prepared by a Surveyor(s) licensed to practice in the State where the
Property is located. During the Study Period, Prentiss shall have the right to
update such Surveys, at Prentiss' sole cost. On or before the Closing Date,
Prentiss shall cause the Title Company to furnish to Prentiss, at Grande B's
sole cost and expense, (i) a title insurance commitment bearing an effective
date subsequent to the date of this Agreement issued by the Title Company
covering the Real Property, binding the Title Company to issue a ALTA Form
Owner's Policy of Title Insurance, showing title to be held currently by Grande
B in a good, indefeasible and insurable condition, together with legible copies
of all documents identified in such title insurance commitment as exceptions to
title certified as true and complete by the Title Company (collectively, the
"Title Commitment"), and (ii) reports of searches of the Uniform Commercial Code
records of both the county and State in which the Property is located
(collectively, the "UCC Reports") with respect to the state of title to the

                                       10
<PAGE>

Property. Prior to the expiration of the Study Period, Prentiss shall notify
Grande B of any matters shown on the Survey or identified in the Title
Commitment or the UCC Reports that Prentiss is unwilling to accept
(collectively, "Prentiss' Objections"). If any of Prentiss' Objections consist
of delinquent taxes, mortgages, deeds of trust, security agreements,
construction or mechanics' liens, tax liens or other liens or charges in a fixed
sum or capable of computation as a fixed sum, then, to that extent,
notwithstanding anything herein to the contrary, Grande B shall be obligated to
pay and discharge (or bond against in a manner sufficient to cause the Title
Company to insure over such Prentiss' Objections) any such Prentiss' Objections
and Escrow Agent is authorized to pay and discharge at Closing such Prentiss'
Objections to the extent not paid and discharged or bonded against at Closing.
Grande B shall not be obligated to incur any expenses to cure any non-monetary
Prentiss' Objections (including, without limitation, any lis pendens filed
against the Property) unless Grande B agrees to cure such non-monetary Prentiss'
Objections as hereinafter provided. Grande B shall notify Prentiss on or before
the Closing Date whether Grande B agrees to cure such non-monetary Prentiss'
Objections. If Grande B notifies Prentiss in writing on or before the Closing
Date that Grande B agrees to cure such non-monetary Prentiss' Objections, Grande
B shall correct such non-monetary Prentiss' Objections on or before the Closing
Date to the reasonable satisfaction of Prentiss. If Grande B does not notify
Prentiss on or before the Closing Date of its agreement to cure such
non-monetary Prentiss' Objections, Grande B shall be deemed to have elected not
to cure such non-monetary Prentiss' Objections, and Prentiss shall elect (1) to
waive such non-monetary Prentiss' Objections or (2) to terminate this Agreement,
in which case the Deposit shall be promptly returned to Prentiss and the parties
hereto shall be released from all further obligations hereunder except those
which expressly survive a termination of this Agreement. Grande B shall not,
after the date of this Agreement, subject the Real Property to or permit or
suffer to exist any liens, encumbrances, covenants, conditions, restrictions,
easements or other title matters or seek any zoning changes or take any other
action which may affect or modify the status of title without Prentiss' prior
written consent. All title matters revealed by the Title Commitment, UCC Reports
and Survey and not objected to by Prentiss as provided above (other than those
rendering title defeasible and delinquent taxes, mortgages, deeds of trust,
security agreements and other liens and charges that are to be paid at Closing
or bonded against as provided above) shall be deemed Permitted Title Exceptions.
Notwithstanding the foregoing, Prentiss shall not be required to take title to
the Real Property subject to any matters which (i) may arise subsequent to the
effective date of the Title Commitment, UCC Reports and Survey examined by
Prentiss during the Study Period and (ii) impairs title to any portion of the
Property and will not be released or bonded against on or before the Closing
Date. If a title exception is disclosed by the Title Company which was not shown
in the Title Commitment or Survey and was not the result of Grande B's acts or
omissions, then, unless Grande B notifies Prentiss in writing by the Closing
Date that Grande B agrees to take such action as may be necessary to release
such title exception on or before the Closing Date, Prentiss may (i) terminate
this Agreement by written notice to Grande B, in which event the Deposit shall
be promptly returned to Prentiss and the parties hereto shall be released from
all further obligations hereunder except those which expressly survive a
termination of this Agreement, or (ii) waive its objections to such title
exception and consummate the transactions contemplated herein.

                                       11
<PAGE>

                                  ARTICLE III.
                    GRANDE B'S REPRESENTATIONS AND WARRANTIES

         To induce Prentiss to enter into this Agreement and to acquire the
Property, Grande B and Brandywine OP hereby, jointly and severally, make the
following representations and warranties with respect to the Property, upon each
of which Grande B and Brandywine OP acknowledge and agree that Prentiss is
entitled to rely and has relied:

         3.1 Organization and Power. Grande B and Brandywine OP are limited
partnerships duly formed, validly existing and in good standing under the laws
of the State of Delaware, are duly qualified to transact business in the
Commonwealth of Virginia, and have all requisite powers and all material
governmental licenses, authorizations, consents and approvals to carry on their
respective business as now conducted and to enter into and perform their
respective obligations hereunder and under any document or instrument required
to be executed and delivered on behalf of Grande B and/or Brandywine OP
hereunder.

         3.2 Authorization, Execution and Disclosure. This Agreement has been
duly authorized by all necessary action on the part of Grande B and Brandywine
OP, has been duly executed and delivered by Grande B and Brandywine OP,
constitutes the valid and binding agreement of Grande B and Brandywine OP and is
enforceable in accordance with its terms, subject to the effect of applicable
bankruptcy, insolvency, reorganization, arrangement, moratorium or other similar
laws affecting the rights of creditors generally. There is no other person or
entity who has an ownership interest in the Property or whose consent is
required in connection with Grande B's performance of its obligations hereunder
which has not been obtained. The person executing this Agreement on behalf of
Grande B and Brandywine OP have the authority to do so. Neither Grande B nor
Brandywine OP has or will intentionally conceal any information regarding the
Property.

         3.3 Non-contravention. The execution and delivery of, and the
performance by Grande B and Brandywine OP of their respective obligations under,
this Agreement do not and will not (a) contravene, or constitute a default
under, any provision of (i) Grande B's Organizational Documents, (ii) applicable
law or regulation or any agreement, judgment, injunction, order, decree or other
instrument binding upon Grande B or Brandywine OP or to which the Property is
subject, the result of which could have a material adverse effect on the value
of the Property or Grande B's ability to convey the Property to Prentiss and/or
Grande B's or Brandywine OP's ability to perform its respective obligations
under this Agreement, or (iii) result in the creation of any lien or other
encumbrance on any asset of Grande B. There are no outstanding agreements
(written or oral) pursuant to which Grande B (or any predecessor to or
representative of Grande B) has agreed to sell or has granted an option or right
of first refusal to purchase the Property or any part thereof.

                                       12
<PAGE>

         3.4 No Special Taxes. Grande B has no knowledge of, nor has it received
any notice of, any special taxes or assessments relating to the Property or any
part thereof or any planned public improvements that may result in a special tax
or assessment against the Property.

         3.5 Compliance with Existing Laws and Restrictive Covenants. To Grande
B's knowledge, Grande B possesses all Authorizations, each of which is valid and
in full force and effect, and no provision, condition or limitation of any of
the Authorizations has been breached or violated. Grande B has received no
notice within the past three years, of any existing or threatened violation of
any provision of any (a) Applicable Laws including, but not limited to, those of
environmental agencies or insurance boards of underwriters with respect to the
ownership, operation, use, maintenance or condition of the Property or any part
thereof, or requiring any repairs or alterations to the Property other than
those that have been made prior to the date hereof, and (b) restrictive
covenants or deed restrictions affecting the Real Property.

         3.6 Personal Property. All of the Personal Property being conveyed by
Grande B hereunder is free and clear of all liens and encumbrances except for
those which will be discharged by Grande B at Closing, and Grande B has good and
merchantable title thereto and the right to convey same in accordance with the
terms of this Agreement.

         3.7 Operating Agreements. There are no management, service, supply,
maintenance, employment or other contracts in effect with respect to the
Property of any nature whatsoever, written or oral, other than the Assumed
Operating Agreements listed on Schedule 3.7 hereof and the Operating Agreements
to be terminated pursuant to the last sentence of this Section 3.7. To Grande
B's knowledge, Grande B has performed all of its obligations under each of the
Assumed Operating Agreements in all material respects and no fact or
circumstance has occurred which, by itself or with the passage of time or the
giving of notice or both, would constitute a default under any of the Assumed
Operating Agreements. To Grande B's knowledge, all other parties to the Assumed
Operating Agreements have performed all of their obligations thereunder in all
material respects, and are not in default thereunder in any material respect.
Grande B has received no notice of any intention by any of the parties to any of
the Assumed Operating Agreements to cancel the same, nor has Grande B canceled
any of same. Grande B shall cause any Operating Agreements which are terminable
without penalty to be terminated as of the Closing Date, which obligation shall
not include the Assumed Operating Agreements.

         3.8 Condemnation Proceedings; Roadways. Grande B has received no notice
of any condemnation or eminent domain proceeding pending or, to Grande B's
knowledge, no such action is threatened, against the Property or any part
thereof. Grande B has no knowledge of any change or proposed change in the
route, grade or width of, or otherwise affecting, any street, creek or road
adjacent to or serving the Real Property.

         3.9 Actions or Proceedings. There is no action, suit or proceeding
pending or known to Grande B to be threatened against or affecting Grande B or
Brandywine OP in any court, before any arbitrator or before or by any
Governmental Authority which (a) in any manner raises any question affecting the
validity or enforceability of this Agreement or any other agreement or
instrument to which Grande B is a party or by which it is bound and that is or
is to be used in connection with, or is contemplated by, this Agreement, (b) is
reasonably likely to materially and adversely affect the business, financial
position or results of operations of Grande B or Brandywine OP or the Property,
(c) is reasonably likely to materially and adversely affect the ability of
Grande B or Brandywine OP to perform its respective obligations hereunder, or
under any document to be delivered pursuant hereto, (d) is reasonably likely to
create a lien on the Property, any part thereof or any interest therein or (e)
is reasonably likely to otherwise materially and adversely affect the Property,
any part thereof or any interest therein or the use, operation, condition or
occupancy thereof.

                                       13
<PAGE>

         3.10 Bankruptcy. No Act of Bankruptcy has occurred with respect to
Grande B or Brandywine OP.

         3.11 Hazardous Substances. To Grande B's knowledge, neither Grande B
nor any previous owner, tenant, occupant or user of the Property, nor any other
person, has engaged in or permitted any operations or activities upon, or any
use or occupancy of the Property or any portion thereof, for the purpose of or
in any way involving the handling, manufacture, treatment, storage, use,
generation, release, discharge, refining, dumping or disposal of any Hazardous
Materials on, under, in or about the Property in violation of any Applicable
Laws. To Grande B's knowledge, no Hazardous Materials have migrated from or to
the Property upon, about, or beneath other properties in violation of any
Environmental Requirements. To Grande B's knowledge, neither the Property nor
its existing or prior uses fail or failed to materially comply with
Environmental Requirements. Grande B has no knowledge of any permits, licenses
or other authorizations which are required under any Environmental Requirements
with regard to the current uses of the Property which have not been obtained and
complied with. To Grande B's knowledge, neither Grande B nor any prior owner,
occupant or user of the Property has received any written notice concerning any
alleged violation of Environmental Requirements in connection with the Property
or any liability for Environmental Damages in connection with the Property for
which Grande B (or Prentiss after Closing) may be liable. To Grande B's
knowledge, no Hazardous Materials are constructed, deposited, stored or
otherwise located on, under, in or about the Property in violation of any
Environmental Requirements. To Grande B's knowledge, there exists no writ,
injunction, decree, order or judgment outstanding, nor any lawsuit, claim,
proceeding, citation, summons or investigation, pending or threatened, relating
to any alleged violation of Environmental Requirements on the Property, or from
the suspected presence of Hazardous Materials thereon, or relating to any
Environmental Damages. To Grande B's knowledge, there are no underground or
above ground chemical treatment or storage tanks, or gas or oil wells are
located on the Property. The representations and warranties made by Grande B in
this Section 3.11 shall be subject to the matters disclosed in the environmental
reports delivered by Grande B to Prentiss pursuant to Section 2.4(b)(12) hereof.

         3.12 Parties in Possession. There are no parties in possession of the
Property except for tenants under written leases, copies of which will be
delivered to Prentiss pursuant to the terms hereof.

                                       14
<PAGE>

         3.13 Leases. There are no leases, concessions or occupancy agreements
in effect with respect to the Real Property other than the Leases listed on the
Rent Roll attached as Schedule 3.13; and Schedule 3.13 attached hereto is a
complete and correct list of all Leases in effect on the date of this Agreement.
Grande B has not sent out any written notice of any default to any tenant under
any Lease which has not been cured, except as set forth on Schedule 3.13. To
Grande B's knowledge, Grande B has performed all obligations required of it
under all of the Leases and there remain no unfulfilled obligations of Grande B
under the Leases, the nonperformance of which could entitle a tenant to damages
under such Lease or could cause Grande B to be in default under such Lease.
Except as shown on Schedule 3.13, no tenant has given written notice to Grande B
of its intention to institute litigation with respect to any Lease that has not
been dismissed, and Grande B has not been served with a citation notifying
Grande B of any litigation with respect to any Lease that has not been
dismissed. None of the Leases and none of the rents or other amounts payable
thereunder have been assigned, pledged or encumbered except for any assignments,
pledges or encumbrances which will be fully released on or before the Closing
Date. The Rent Roll is true, correct and complete in all material respects as of
the date shown in the Rent Roll and, to Grande B's knowledge, there has been no
material adverse change with respect to any of the items shown on the Rent Roll
during the period from the date thereof to the date of this Agreement, except as
shown thereon.

         3.14 Leased Property. To Grande B's knowledge, all leases of the Leased
Property, if any, are in good standing and free from default.

         3.15 No Unpaid Charges. Subject to Section 7.8 hereof, there are no
unpaid charges, debts, liabilities, claims or obligations arising from the
construction, occupancy, ownership, use or operation of the Property which could
give rise to any mechanic's or materialmen's or other statutory lien against the
Property, or any part thereof, or for which Prentiss will be responsible or
which will be due upon the initial occupancy of vacant space (such as a water or
sewer connection or tap-in fee).

         3.16 Condition of Improvements. Grande B has not received any written
notice, from any third party alleging that (a) any of the Improvements (i) are
defective in design or construction, (ii) are not in operating condition and a
satisfactory state of repair, or (iii) have roof leaks, (b) any mechanical
systems are not in reasonable working order and repair, or (c) Grande B has
failed to operate the Property in a commercially reasonable manner consistent
with a modern office building; provided, however, the foregoing representation
and warranty as to notices received shall not include any representation or
warranty as to notices concerning the aesthetic or other subjective quality of
the design of the Property or any system, element or component thereof and no
representation or warranty shall be deemed made as to any defect disclosed in
any property condition report obtained by Prentiss in connection with the
Property.

         3.17 Access. Grande B has no knowledge of any pending or threatened
governmental proceeding or any other fact or condition which would limit or
result in the termination of the Property's existing access to and from public
streets or roads.

         3.18 No Commitments. No commitments have been made to any Governmental
Authority, utility company, school board, church or other religious body, or any
homeowners' association or any other organization, group or individual, relating
to the Property which would impose an obligation upon Prentiss to make any
contribution or dedication of money or land or to construct, install or maintain
any improvements of a public or private nature on or off the Property. Without
limiting the generality of the foregoing, Grande B is not a party to any paving
agreements or undertakings, payback agreements, revenue bonds, utility debt
service expenses or other charges or expenses upon or relating to any of the
Property or applicable thereto.

                                       15
<PAGE>

         3.19 Grande B Is Not a "Foreign Person". Grande B is not a "foreign
person" within the meaning of Section 1445 of the Internal Revenue Code, as
amended (i.e., Grande B is not a foreign corporation, foreign partnership,
foreign trust, foreign estate or foreign person as those terms are defined in
the Internal Revenue Code and regulations promulgated thereunder).

         3.20 Leasing Commissions. No brokerage or leasing commissions or other
fees or compensation are due or payable, or will become due and payable as a
result of agreements in place, to any person, firm, corporation or other entity
with respect to or on account of any of the Leases or any extension or renewals
thereof, except as set forth on Schedule 3.20 or 6.4(g) hereof.

         3.21 Other Agreements. There are no options, contracts or other
obligations outstanding for the sale, exchange or transfer of any of the
Property or any interest therein which would be superior to the rights of
Prentiss under this Agreement or which would survive Closing.

         3.22 Existing Secured Indebtedness. There is no debt secured by liens
on the Real Property, or any portion thereof, which will not be released and
discharged as of the Closing.

         3.23 Employment on "At-Will" Basis. All persons and entities presently
employed in connection with the operation and maintenance of the Property are
employed on an "at will" basis, are dischargeable upon thirty (30) days' notice
and, unless otherwise directed by Prentiss, shall be terminated by Grande B as
of Closing. There are no labor disputes pending, nor to the best of Grande B's
knowledge, contemplated pertaining to the operation or maintenance of the
Property, or any part thereof. Grande B has no employment agreements, either
written or oral, with any person which would require Prentiss to employ any
person after the date hereof or the Closing Date.

         3.24 LIMITATIONS ON REPRESENTATIONS AND WARRANTIES. PRENTISS HEREBY
AGREES AND ACKNOWLEDGES THAT, EXCEPT AS SET FORTH IN THIS ARTICLE III, OR AS
OTHERWISE EXPRESSLY STATED HEREIN OR IN THE DEED OR IN ANY DOCUMENTS EXECUTED IN
CONNECTION HEREWITH, NEITHER GRANDE B NOR ANY AGENT, ATTORNEY, EMPLOYEE OR
REPRESENTATIVE OF GRANDE B HAS MADE ANY REPRESENTATION WHATSOEVER REGARDING THE
SUBJECT MATTER OF THIS AGREEMENT, OR ANY PART HEREOF, INCLUDING (WITHOUT
LIMITING THE GENERALITY OF THE FOREGOING) REPRESENTATIONS OR WARRANTIES AS TO
THE PHYSICAL NATURE OR CONDITION OF THE PROPERTY OR THE CAPABILITIES THEREOF,
AND THAT PRENTISS, IN EXECUTING, DELIVERING AND/OR PERFORMING THIS AGREEMENT,
DOES NOT RELY UPON ANY STATEMENT AND/OR INFORMATION TO WHOMEVER MADE OR GIVEN,
DIRECTLY OR INDIRECTLY, ORALLY OR IN WRITING, BY ANY INDIVIDUAL, FIRM OR
CORPORATION EXCEPT THOSE EXPRESSLY CONTAINED HEREIN OR DELIVERED PURSUANT
THERETO OR IN ANY DOCUMENTS EXECUTED IN CONNECTION HEREWITH. EXCEPT AS OTHERWISE
PROVIDED HEREIN, PRENTISS AGREES TO TAKE THE PROPERTY "AS IS," AS OF THE DATE
HEREOF, REASONABLE WEAR AND TEAR EXCEPTED. IN ADDITION, EXCEPT AS SET FORTH
HEREIN, GRANDE B MAKES NO REPRESENTATIONS OR WARRANTIES REGARDING THE COMPLIANCE
WITH ANY ENVIRONMENTAL REQUIREMENTS, INCLUDING THE EXISTENCE IN OR ON THE
PROPERTY OF HAZARDOUS MATERIALS. THE PROVISIONS OF THIS PARAGRAPH SHALL SURVIVE
THE CLOSING OR ANY TERMINATION HEREOF.

                                       16
<PAGE>

Each of the representations and warranties contained in this Article III and its
various subparagraphs are intended for the benefit of Prentiss and may be waived
in whole or in part by Prentiss. All rights and remedies arising in connection
with the untruth or inaccuracy of any such representations and warranties shall
survive the Closing of the transaction contemplated hereby as provided in
Section 10.11 hereof, except to the extent that Grande B gives Prentiss written
notice prior to Closing of the untruth or inaccuracy of any representation or
warranty, Prentiss otherwise obtains actual knowledge prior to Closing of the
untruth or inaccuracy of any representation or warranty, and Prentiss
nevertheless elects to close this transaction. Prentiss shall be deemed to have
actual knowledge of the untruth or inaccuracy of any representation or warranty
only if (i) Prentiss receives written notice from Grande B satisfying the
foregoing requirements, or (ii) Thomas F. August, Robert K. Wiberg, Michael
Cooper or J. Kevan Dilbeck has actual knowledge of any such untruth or
inaccuracy. Except to the extent otherwise expressly provided in the immediately
preceding sentence, no investigation, audit, inspection, review or the like
conducted by or on behalf of Prentiss shall be deemed to terminate the effect of
any such representations, warranties and covenants, it being understood that
Prentiss has the right to rely thereon and that each such representation and
warranty constitutes a material inducement to Prentiss to execute this Agreement
and to close the transaction contemplated hereby and to pay the Purchase Price
to Grande B.

If any of Grande B's representations and warranties made hereunder are found by
Prentiss to be incorrect prior to Closing to the extent they affect the Property
or its operation in any material respect, Prentiss shall inform Grande B in
writing and Prentiss' sole remedy, except as otherwise expressly provided in
clause (a)(ii) of the first sentence of Section 9.3 hereof or the last sentence
of Section 9.3 hereof, shall be termination of this Agreement on account thereof
and refund of the Deposit. If Prentiss elects not to so terminate this
Agreement, any remedy of Prentiss for breach of such warranties and
representations made prior to the Closing shall be deemed to be irrevocably
waived. Notwithstanding anything to the contrary contained in this Article, if
Grande B breaches any representation or warranty made by Grande B and if prior
to Closing Prentiss notifies Grande B that it elects to terminate this Agreement
on account of such breach, Grande B may by written notice to Prentiss given or
before the Closing Date agree to cure the breach (which breach must be cured on
or before the Closing Date), and Prentiss shall thereupon be obligated to close
the transaction and accept such cure as Prentiss' sole remedy for such breach.

The term "to Grande B's knowledge" or similar phrase shall mean the knowledge of
Grande B's and Brandywine OP's chief executive officer, general counsel, chief
financial officer and the current building engineer, property manager and
leasing agent (collectively, "Grande B's Personnel with Knowledge") for the
Property and such inquiry shall include the direction by Grande B to such
persons to review all files in their possession relating to the operation,
ownership, maintenance and management of the Property. Grande B covenants that
if prior to Closing Grande B obtains actual knowledge that any of the facts
represented and warranted by Grande B under this Agreement are or become untrue
or inaccurate in any material respect, it will promptly inform Prentiss in
writing of its discovery.

                                       17
<PAGE>

Grande B's Personnel with Knowledge shall not have any personal liability under
this Agreement in their respective capacities as officers and/or directors of
Grande B.

                                  ARTICLE IV.
                    PRENTISS' REPRESENTATIONS AND WARRANTIES

         To induce Grande B to enter into this Agreement and to convey the
Property, Prentiss hereby makes the following representations and warranties,
upon each of which Prentiss acknowledges and agrees that Grande B is entitled to
rely and has relied:

         4.1 Organization and Power. Prentiss is a limited partnership, duly
formed, validly existing and in good standing under the laws of the State of
Delaware, and has all requisite partnership powers and all material governmental
licenses, authorizations, consents and approvals required to carry on its
business as now conducted and to enter into and perform its obligations under
this Agreement and any document or instrument required to be executed and
delivered on behalf of Prentiss hereunder. Prentiss has the financial capability
to acquire the Property pursuant to this Agreement.

         4.2 Non-contravention. The execution and delivery of this Agreement and
the performance by Prentiss of its obligations hereunder do not and will not
contravene, or constitute a default under, any provisions of Prentiss'
Organizational Documents or applicable law or regulation, or any agreement,
judgment, injunction, order, decree or other instrument binding upon Prentiss.

         4.3 Litigation. There is no action, suit or proceeding, pending or
known to be threatened, against or affecting Prentiss in any court or before any
arbitrator or before any Governmental Authority which (a) in any manner raises
any question affecting the validity or enforceability of this Agreement or any
other agreement or instrument to which Prentiss is a party or by which it is
bound and that is to be used in connection with, or is contemplated by, this
Agreement, (b) could materially and adversely affect the business, financial
position or results of operations of Prentiss, or (c) could materially and
adversely affect the ability of Prentiss to perform its obligations hereunder,
or under any document to be delivered pursuant hereto.

         4.4 Bankruptcy. No Act of Bankruptcy has occurred with respect to
Prentiss.

         4.5 Authorization, Execution and Disclosure. This Agreement has been
duly authorized by all necessary action on the part of Prentiss, has been duly
executed and delivered by Prentiss, constitutes the valid and binding agreement
of Prentiss and is enforceable in accordance with its terms, subject to the
effect of applicable bankruptcy, insolvency, reorganization, arrangement,
moratorium or other similar laws affecting the rights of creditors generally.

                                   ARTICLE V.
                              CONDITIONS PRECEDENT

         5.1 As to Prentiss' Obligations. Prentiss' obligations hereunder are
subject to the satisfaction of the following conditions precedent:

                                       18
<PAGE>

             (a) Grande B's Deliveries. Grande B shall have delivered to or for
the benefit of Prentiss, on or before the Closing Date, all of the documents and
other information required of Grande B pursuant to Sections 7.2 and 7.4 hereof.

             (b) Representations, Warranties and Covenants; Obligations of
Grande B; Certificate. All of Grande B's representations and warranties made in
this Agreement shall be true and correct in all material respects as of the date
hereof and as of the date of Closing as if then made; Grande B shall have
performed in all material respects all of its covenants and other obligations
under this Agreement; and Grande B shall have executed and delivered to Prentiss
at Closing a certificate to the foregoing effect.

             (c) Title Insurance. Good and indefeasible fee simple title to the
Real Property shall be insurable as such by the Title Company, subject only to
Permitted Title Exceptions as determined in accordance with Section 2.4 hereof
and including, without limitation, all applicable deletions of standard
exceptions and endorsements permitted under applicable state law which are
customarily required by institutional investors purchasing property comparable
to the Property.

             (d) Simultaneous Closings. There shall occur, simultaneously with
Closing hereunder, closing under the Second Exchange Agreement.

             (e) Condition of Improvements. The Improvements and the Tangible
Personal Property (including but not limited to the mechanical systems,
plumbing, electrical, wiring, fixtures, heating, air conditioning and
ventilating equipment, elevators, boilers, equipment, roofs, structural members
and furnaces) shall be in the same condition at Closing as they are as of the
date hereof, reasonable wear and tear excepted. Grande B shall not have removed
or caused or permitted to be removed any part or portion of the Real Property or
the Tangible Personal Property without Prentiss' prior written consent unless
the same is replaced, prior to Closing, with a similar item of at least equal
suitability, quality and value, free and clear of any lien or security interest.

             (f) Utilities. All of the Utilities shall be installed in and
operating at the Property, and service shall be available for the removal of
garbage and other waste from the Property.

             (g) Due Diligence Materials. All rent rolls, lists, schedules and
other documents furnished by Grande B to Prentiss under this Agreement shall be
true and correct in all material respects, except for inaccuracies as to which
Prentiss was given written notice by Grande B or otherwise had actual knowledge
prior to the end of the Study Period.

             (h) No Additional Proceedings; Tenant Defaults. Except for matters
as to which Prentiss was given written notice by Grande B or otherwise had
actual knowledge prior to the end of the Study Period, on the Closing Date,
there shall be no (a) litigation pending or threatened, seeking (i) to enjoin
the consummation of the transactions contemplated hereunder, (ii) to recover
title to the Property, or any part thereof or any interest therein, (iii) to
increase substantially ad valorem taxes theretofore assessed against any of the
Property, (iv) to enjoin the violation of any law, rule, regulation, restrictive
covenant or zoning ordinance that may be applicable to the Property, or (v)
claiming defaults or other liability of Grande B under Leases by tenants leasing
five percent (5%) or more of the rentable square feet of the Improvements, in
the aggregate or (b) monetary default in excess of thirty (30) days for which a
written notice of default has been given to a tenant and which constitutes an
event of default under, and as defined in, the applicable Lease, other material
default or any threatened or reasonably anticipated material default by tenants
leasing five percent (5%) or more of the rentable square feet of the
Improvements, in the aggregate.

                                       19
<PAGE>

             (i) Estoppel Letters. The estoppel letters to be delivered at
Closing pursuant to Section 7.2(g) hereof shall have been obtained and delivered
and shall reflect no facts at material variance with the facts disclosed on the
Rent Roll and records provided to Prentiss during the Study Period.

             (j) Other Estoppel Letters. Estoppel letters described in Section
7.2(w) hereof.

Each of the conditions contained in this Section 5.1 are intended for the
benefit of Prentiss and may be waived in whole or in part, by Prentiss, but only
by an instrument in writing signed by Prentiss.

         5.2 As to Grande B's Obligations. Grande B's obligations hereunder are
subject to the satisfaction of the following conditions precedent:

             (a) Prentiss' Deliveries. Prentiss shall have delivered to or for
the benefit of Grande B, on or before the Closing Date, all of the documents and
payments required of Prentiss pursuant to Sections 7.3 and 7.4 hereof.

             (b) Representations, Warranties and Covenants; Obligations of
Prentiss. All of Prentiss' representations and warranties made in this Agreement
shall be true and correct in all material respects as of the date hereof and as
of the date of Closing as if then made and Prentiss shall have performed in all
material respects all of its covenants and other obligations under this
Agreement.

             (c) Simultaneous Closings. There shall occur, simultaneously with
Closing hereunder, closing under the Second Exchange Agreement.

Each of the conditions contained in this Section are intended for the benefit of
Grande B and may be waived in whole or in part, by Grande B, but only by an
instrument in writing signed by Grande B.

                                  ARTICLE VI.
                              COVENANTS OF GRANDE B

         To induce Prentiss to enter into this Agreement and to acquire the
Property in exchange for the Exchange Property, Grande B covenants and agrees to
the following:

         6.1 Operating Agreements. Prior to the Closing Date, Grande B shall not
enter into any new management agreement, maintenance or repair contract, supply
contract, lease in which it is lessee or other agreements with respect to the
Property which cannot be terminated on or before the Closing Date, nor shall
Grande B enter into any agreements modifying the Operating Agreements in any
material respect, unless (a) any such agreement or modification will not bind
Prentiss or the Property after the date of Closing or (b) Grande B has obtained
Prentiss' prior written consent to such agreement or modification. Grande B
agrees to cancel and terminate effective as of the Closing Date all property
management agreements affecting the Property or any portion thereof.

                                       20
<PAGE>

         6.2 Warranties and Guaranties. Grande B shall not before or after
Closing release or modify any Warranties and Guaranties, if any, except with the
prior written consent of Prentiss.

         6.3 Insurance. Prior to the Closing Date, Grande B shall pay all
premiums on, and shall not cancel or voluntarily allow to expire, any of Grande
B's Insurance Policies unless such policy is replaced, without any lapse of
coverage, by another policy or policies providing coverage at least as extensive
as the policy or policies being replaced. Grande B hereby indemnifies and holds
Prentiss harmless from and against all losses, costs, damages and expenses
resulting from actions involving bodily or personal injury or property damage in
or about any of the Property that occurred prior to the Closing Date, regardless
of when the claim was made, but only to the extent coverage under the applicable
Insurance Policy or Policies is not sufficient and paid, and this indemnity
shall survive the Closing Date.

         6.4 Operation of Property Prior to Closing. Grande B and Brandywine OP
represent, warrant, covenant and agree with Prentiss that, between the date of
this Agreement and the date of Closing:

             (a) Subject to the restrictions contained herein, Grande B shall
operate the Property in the same manner in which Grande B operated the Property
prior to the execution of this Agreement, so as to keep the Property in good
condition, reasonable wear and tear excepted.

             (b) Grande B shall maintain its books of account and records in the
usual, regular and ordinary manner, in accordance with sound accounting
principles applied on a basis consistent with the basis used in keeping its
books in prior years.

             (c) Grande B shall maintain in full force and effect all Insurance
Policies.

             (d) Grande B shall punctually perform and discharge all obligations
and undertakings of Grande B under the Leases and shall not permit a default by
Grande B to occur thereunder.

             (e) Grande B shall use and operate the Property in compliance with
Applicable Laws and the requirements of any mortgage, ground lease, Lease,
Operating Agreement and Insurance Policy affecting the Property.

             (f) Grande B shall cause to be paid prior to delinquency all ad
valorem and other taxes due and payable with respect to the Property or its
operation.

                                       21
<PAGE>

             (g) Without the express prior written consent of Prentiss (which
consent shall not be unreasonably withheld and shall be deemed to have been
given if Prentiss fails to respond to a written request from Grande B for such
consent within two (2) business days following Prentiss' receipt of any such
request), Grande B shall not: (i) enter into new Leases of any kind or nature
affecting the Property; or (ii) grant a renewal or extension of any existing
Lease, or consent to any assignment, sublease or expansion of any existing lease
or portion thereof which, by the terms of any such Lease, requires Grande B's
prior consent as a condition to any such renewal, extension, assignment,
sublease or expansion. Grande B shall not, without the express written consent
of Prentiss, in any manner change, modify, extend, renew or terminate any Lease
except as required by the terms thereof, or waive in any material respect any of
the tenant's obligations under any Lease. Grande B shall not apply all or any
part of the security or damage deposit of a tenant under any Lease to
obligations of such tenant, unless such tenant has vacated its portion of the
Property as of the Closing Date. Notwithstanding the foregoing, Prentiss hereby
approves the new Leases which have been entered into by Grande B and costs
associated therewith, as more particularly described in Schedule 6.4(g) hereto.

             (h) Grande B shall cause all debts and liabilities for labor,
materials, services and equipment incurred in the construction, operation and
development of the Property, including leasehold improvements, to be promptly
paid.

             (i) Neither Grande B nor Grande B's managing agent shall (1) make
any agreements which shall be binding upon Prentiss with respect to the
Property, or (2) reduce, or cause to be reduced any rents or any other revenues
over which Grande B has operational control.

             (j) Grande B shall promptly deliver to Prentiss upon Prentiss'
request such reports showing the revenue and expenses of the Property as Grande
B customarily keeps or receives internally for its own use.

             (k) Except as required by the terms thereof or hereof, Grande B
shall not in any manner change, modify, extend, renew or terminate any Operating
Agreement which would be binding on Prentiss with respect to the Property
without the express written consent of Prentiss.

             (l) Grande B shall promptly advise Prentiss of any litigation,
arbitration or administrative hearing concerning or affecting the Property of
which Grande B obtains actual knowledge.

             (m) Grande B shall keep all existing indebtedness, if any, current,
shall comply with the terms and provisions of all debt instruments, not modify
any such debt instruments and shall immediately send Prentiss copies of all
correspondence received from the holder(s) of such debt.

         6.5 No Marketing. Grande B shall not market the Property for sale or
enter into discussions or negotiations with potential purchasers of the Property
unless this Agreement has been terminated pursuant to its terms.

         6.6 Leased Property. Grande B shall be solely responsible for all
obligations relating to the Leased Property, and Prentiss shall have no
obligations with respect thereto. The provisions of this Section 6.6 shall
survive the Closing.

                                       22
<PAGE>

The foregoing covenants of Grande B are for the benefit of Prentiss or its
assignee of its rights under this Agreement.

                                  ARTICLE VII.
                                     CLOSING

         7.1 Closing. The Closing shall occur within five (5) days after the
conditions precedent set forth in Sections 5.1 and 5.2 have been satisfied. As
more particularly described below, at the Closing the parties hereto will meet
to (i) execute all of the documents required to be delivered in connection with
the transactions contemplated hereby (the "Closing Documents"), (ii) deliver the
same to Escrow Agent, and (iii) take all other action required to be taken in
respect of the transactions contemplated hereby. The Closing will occur at the
offices of the Escrow Agent. At the Closing, Prentiss shall deliver all title
instruments transferring title to the Exchange Property in accordance with the
Second Exchange Agreement to Escrow Agent, the Title Company shall update the
title to the Property and, provided there has been no change in the status of
title as reflected in the Title Commitment and Survey which has not been waived
by Prentiss pursuant to Section 2.4(d) hereof, and Escrow Agent shall record the
Deeds, release and date, where appropriate, the Closing Documents in accordance
with the joint instructions of Grande B and Prentiss and shall send, by wire
transfer, all sums, if any, owing to Grande B or Prentiss hereunder to Grande B
or Prentiss, as applicable. At Closing, the Escrow Agent shall additionally
send, by wire transfer, the Deposit, less the Independent Consideration, to
Prentiss. As provided herein, the parties hereto will agree upon adjustments and
prorations to certain items which cannot be exactly determined at the Closing
and will make the appropriate adjustments with respect thereto. Possession of
the Property shall be delivered to Prentiss on the Closing Date, subject only to
Permitted Title Exceptions and the rights of tenants under the Leases.
Notwithstanding anything herein to the contrary, if the Closing Date does not
occur by April 30, 2001, and the provisions of Section 9.3 or 9.5 are not
applicable, then either party may terminate this Agreement by notice to the
other party hereto, in which event neither party shall have any further
obligation to the other except for the indemnities and other provisions of this
Agreement which expressly survive a termination of this Agreement, and the
Deposit, less the Independent Consideration, shall be promptly refunded to
Prentiss.

         7.2 Grande B's Deliveries. At the Closing, Grande B shall deliver to
Escrow Agent all of the following instruments, each of which shall have been
duly executed and, where applicable, acknowledged and/or sworn on behalf of
Grande B and shall be dated as of the Closing Date:

             (a) The certificate required by Section 5.1(b) hereof.

             (b) The Deeds.

             (c) The Bill of Sale - Personal Property.

             (d) The Assignment and Assumption Agreement.

             (e) The Assignment of Leases.

                                       23
<PAGE>

             (f) An updated certified Rent Roll dated as of the date preceding
the Closing Date.

             (g) Either (i) an estoppel letter in the form of Exhibit C hereto
dated not more than thirty (30) days prior to the Closing Date (a) from each of
the tenants under the Leases covering 7,500 square feet or more, and (b) from
tenants leasing, in the aggregate, at least seventy-five percent (75%) of the
remainder of the Improvements, or (ii) an estoppel letter executed by Grande B
certifying to the matters specified in Exhibit C hereto for any tenant which
does not execute an estoppel letter. Any estoppel letter provided by Grande B
for a Lease pursuant to clause (ii) above shall state that Grande B shall have
no liability thereunder if Grande B subsequently provides to Prentiss an
estoppel letter in the form of Exhibit C from the tenant under such Lease.

             (h) Such agreements, affidavits or other documents as may be
required by the Title Company to issue the Owner's Title Policy subject only to
the Permitted Title Exceptions and to eliminate such standard exceptions and to
issue the endorsements thereto which are customarily required by institutional
investors purchasing property comparable to the Property.

             (i) An updated Title Commitment issued by the Title Company, dated
as of the date and time of Closing, subject only to the Permitted Title
Exceptions.

             (j) The FIRPTA Certificate.

             (k) All original Warranties and Guaranties in Grande B's possession
or reasonably available to Grande B.

             (l) To the extent in Grande B's possession or reasonably available
to Grande B, a valid, final and unconditional certificate of occupancy for the
Real Property and Improvements, issued by the appropriate Governmental Authority
and, if required by Applicable Laws, transferred to Prentiss.

             (m) The originals of the Assumed Operating Agreements, duly
assigned to Prentiss and with such assignment acknowledged and approved by the
other parties to such Assumed Operating Agreements to the extent required by
such Assumed Operating Agreements.

             (n) An assignment of each of the leases of the Leased Property to
Prentiss, together with (i) the written consent of the lessors of such leases to
such assignment, if required by such leases, and (ii) executed originals of all
such leases in Grande B's possession or reasonably available to Grande B.

             (o) Executed originals of all Leases, leases of Leased Property,
permits and, to the extent in Grande B's possession or control, Authorizations
transferred or assigned to Prentiss at Closing as required hereunder and any
other documents or instruments affecting the Property or the ownership and
operation thereof.

             (p) All current real estate and personal property tax bills in
Grande B's possession or under its control.

                                       24
<PAGE>

             (q) All books, records, operating reports, appraisal reports, files
and other materials in Grande B's possession or control which are necessary in
Prentiss' reasonable discretion to maintain continuity of operation of the
Property. Prentiss covenants to permit Grande B to photocopy any of the matters
described in this Subparagraph 7.2(q) for a period of three (3) years following
the Closing Date, which covenant of Prentiss shall survive for such three (3)
year period.

             (r) Written notice executed by Grande B notifying all interested
parties, including, without limitation, all tenants under any Leases, that the
Property has been conveyed to Prentiss effective as of the Closing Date and
directing that all payments, inquiries and the like be forwarded to Prentiss at
the address to be provided by Prentiss (or as otherwise directed by Prentiss).

             (s) A current UCC Report showing no financing statements by Grande
B as Debtor covering the Property.

             (t) All keys to all locks on the Property in the possession of
Grande B, together with an accounting for such keys in the possession of others.

             (u) Possession of the Property subject only to the Permitted Title
Exceptions.

             (v) Certified copies of a incumbency certificate and resolutions
authorizing the execution by Grande B of this Agreement and all documents to be
executed by Grande B on the Closing Date.

             (w) Estoppel letters from each owners association created pursuant
to restrictive covenants or deed restrictions affecting the Real Property
certifying that (i) the Real Property complies with such restrictive covenants
or deed restrictions, and (ii) no assessments are due and owing with respect to
the Real Property, and estoppel letters from adjoining property owners who are
parties to adjoining landowner agreements binding on any portion of the Real
Property; provided, Grande B may execute an estoppel letter certifying to the
foregoing matters for an owners association or property owner that does not
execute any such estoppel letter, which estoppel letter shall continue in effect
unless and until the applicable estoppel letter is subsequently provided from
any such owners association or property owner.

             (x) Any other document or instrument reasonably requested by
Prentiss in connection with the transactions contemplated hereby.

         7.3 Prentiss' Deliveries.

             (a) At the Closing, Prentiss shall deliver to Escrow Agent all
title instruments transferring title to the Exchange Property, as set forth on
Exhibit B hereof, in accordance with Section 2.1 hereof and as required by the
terms and conditions of the Second Exchange Agreement.

             (b) At the Closing, Prentiss shall deliver to Grande B the
Assignment and Assumption Agreement and the Assignment of Leases, duly executed
by Prentiss.

                                       25
<PAGE>

             (c) At the Closing, Prentiss shall deliver to Grande B any other
document or instrument reasonably requested by Grande B in connection with the
transactions contemplated hereby.

         7.4 Mutual Deliveries. At the Closing, Prentiss and Grande B shall
mutually execute and deliver each to the other:

             (a) A final closing statement reflecting the adjustments and
prorations required hereunder and the allocation of income and expenses required
hereby.

             (b) Such other and further documents, papers and instruments as may
be reasonably required by the parties hereto in connection with the transactions
contemplated hereby or their respective counsel.

         7.5 Closing Costs. Except as is explicitly provided in this Agreement,
each party hereto shall pay its own legal fees and expenses. Grande B shall pay
for the costs associated with the releases of any deeds of trust, mortgages and
other financing encumbering the Property that Grande B is to cause to be
released pursuant to this Agreement and for any costs associated with any
corrective instruments. Grande B shall pay all costs for title searches, tax
certificates and all premiums for the issuance of the Title Policy; all costs of
providing the matters described in Sections 2.4(b) and (d) to Prentiss; the
grantor tax payable by a seller of real property in Virginia; and one-half (1/2)
of any escrow fees or similar charges of the Escrow Agent. Prentiss shall pay
the grantee tax payable by a purchaser of real property in Virginia and one-half
(1/2) of any escrow fees or similar charges of the Escrow Agent. Grande B shall
pay all prepayment penalties and other costs and expenses payable in connection
with debt which Grande B is required to prepay on the Closing Date. Grande B
shall pay all assessments levied or pending against the Property as of the
Closing Date. All other expenses, including transfer taxes, surtaxes, and
documentary transfer stamps, incurred by Grande B or Prentiss with respect to
the Closing shall be borne and paid for exclusively by the party incurring same,
without reimbursement, except to the extent otherwise specifically provided
herein.

         7.6 Revenue and Expense Allocations. All revenues (including operating
expense escalations) and expenses with respect to the Property, and applicable
to the period of time before and after Closing, determined in accordance with
sound accounting principles consistently applied, shall be allocated between
Grande B and Prentiss as provided herein. Grande B shall be entitled to all
revenue and shall be responsible for all expenses for the period of time up to
but not including the Closing Date, and Prentiss shall be entitled to all
revenue and shall be responsible for all expenses for the period of time from,
after and including the date of Closing. Such adjustments shall be shown on the
closing statements (with such supporting documentation as the parties hereto may
require being attached as exhibits to the closing statements) and shall increase
or decrease (as the case may be) the cash amount payable by the parties hereto.
Without limiting the generality of the foregoing, the following items of revenue
and expense shall be allocated at Closing:

             (a) Current rents.

                                       26
<PAGE>

             (b) Real estate and personal property taxes for the Property for
the current calendar year 2001.

             (c) Revenue and expenses under the Assumed Operating Agreements to
be assigned to and assumed by Prentiss.

             (d) Utility charges (including, but not limited to, charges for
water, sewer and electricity).

             (e) Municipal or other governmental improvement liens, which shall
be paid by Grande B at Closing where the work has physically commenced, and
which shall be assumed by Prentiss at Closing where the work has been
authorized, but not physically commenced.

             (f) All other revenues (including CAM charges) and expenses of the
Property.

Prentiss shall receive a credit for purposes of calculating closing prorations
for the total of (i) prepaid rents and (ii) unforfeited security deposits
together with interest thereon held by Grande B under Leases.

Grande B shall pay or cause to be paid all real estate taxes and installments
for special assessments (prorated to the Closing Date) for the Property due and
payable in, or deferred with respect to the years prior to, the year in which
the Closing occurs. All installments for special assessments (prorated to the
Closing Date) pending, levied or due and payable on or prior to the Closing Date
shall be paid by Grande B on or before the Closing Date. All subdivision and
platting costs and expenses heretofore incurred by Grande B, including, without
limitation, all subdivision exactions, fees and costs and all dedication of land
for parks and other public uses or payment of fees in lieu thereof, shall be
paid by Grande B on or prior to the Closing Date.

If accurate allocations cannot be made at Closing because current bills are not
obtainable (as, for example, in the case of utility bills and/or real estate or
personal property taxes), the parties shall allocate such revenue or expenses at
Closing on the best available information, subject to adjustment upon receipt of
the final bill or other evidence of the applicable revenue or expense. The
obligation to make the adjustment shall survive the closing of the transaction
contemplated by this Agreement. Any revenue received or expense incurred by
Grande B or Prentiss with respect to the Property after the Closing Date shall
be promptly allocated in the manner described herein and the parties shall
promptly pay or reimburse any amount due. Grande B shall calculate and deliver
to Prentiss for its approval and its transmittal to tenants under Leases,
reconciliations of operating costs for the calendar year 2000, and Prentiss
shall inform the tenants that Grande B prepared such reconciliations and can be
contacted to discuss any questions concerning such reconciliations. The
proration provisions of this Agreement shall survive the closing of the
transaction contemplated hereby for a period of eighteen (18) months.

         7.7 Delinquent Rents. Any rents or other amounts which are delinquent
as of the Closing shall not be adjusted or prorated at Closing, but Prentiss
shall make a reasonable attempt to collect such amounts for the benefit of
Grande B after the Closing; provided, however, that nothing contained herein
shall be construed to require Prentiss to institute any lawsuit or other
proceedings to collect such delinquent amounts. In this connection, the first
monies collected by Prentiss from tenants or other persons owing delinquent
rents or other amounts shall be applied to Prentiss' costs of collection, then
to the current rents or obligations of such person to Prentiss, and the balance,
if any, shall be delivered to Grande B, to the extent of the delinquency. Grande
B shall be permitted to bring collection suits against tenants owing rent to
Grande B that is more than thirty (30) days in arrears; however, Grande B may
not bring eviction actions against any tenants under any of the Leases.

                                       27
<PAGE>

         7.8 Costs Associated with Certain Leasing Activities. Except as
otherwise expressly set forth in this Section 7.8, all refurbishment allowances,
tenant improvement costs and leasing commissions owing or which could become due
and owing with respect to Leases entered into on or before the Closing Date
shall be paid by Grande B when due, and Grande B shall indemnify and hold
harmless Prentiss for claims brought against the Property or Prentiss arising
therefrom, which indemnity shall survive the Closing. Notwithstanding the
foregoing: (i) Prentiss shall pay to Grande B at the Closing an amount equal to
the cost of all (x) leasing commissions paid by Grande B, prior to the Closing
Date, to brokers other than affiliates of Grande B and (y) capital improvement
costs incurred and paid by Grande B prior to the Closing Date in completing
tenant improvements pursuant to (in the case of both (x) and (y)) (a) Leases
entered into by Grande B on or after January 1, 2001 and other Leases, which are
described on Schedule 6.4(g) or which have been approved or deemed approved by
Prentiss pursuant to Section 6.4(g); (b) renewals, extensions or expansions of
existing Leases expressly requiring the approval of Grande B as a condition to
the exercise of such options which are exercised on or after January 1, 2001,
which either are described on Schedule 6.4(g) or have been approved or deemed
approved by Prentiss pursuant to Section 6.4(g); and (c) renewals, extensions or
expansions of existing Leases not requiring the approval of Grande B as a
condition to the exercise of such options which have been exercised on or after
January 1, 2001; and (ii) Prentiss shall be responsible for refurbishment
allowances, tenant improvement costs and leasing commissions shown in the Rent
Roll or contained in Leases delivered pursuant to Section 2.4(b)(1) hereof that
have not previously been paid by Grande B but are payable following the Closing
Date under existing Leases on or after January 1, 2001 or which are contained in
Leases entered into between January 1, 2001 and the Closing Date which are
described on Schedule 6.4(g) or which have been approved or deemed approved
pursuant to Section 6.4(g) hereof. The provisions of this Section 7.8 shall
survive the Closing Date.

                                 ARTICLE VIII.
                               GENERAL PROVISIONS

         8.1 Condemnation. In the event of any actual or threatened taking,
pursuant to the power of eminent domain, of all or any portion of the Real
Property, or any proposed sale in lieu thereof, Grande B shall give written
notice thereof to Prentiss promptly after Grande B learns or receives notice
thereof. If all or any part of the Real Property is, or is to be, so condemned
or sold, Prentiss shall have the right to terminate this Agreement pursuant to
Section 9.3 hereof. If Prentiss elects not to terminate this Agreement, all
proceeds, awards and other payments arising out of such condemnation or sale
(actual or threatened) shall be paid or assigned, as applicable, to Prentiss at
Closing. Grande B shall not settle or compromise any such proceeding without
Prentiss' written consent. If Prentiss elects to terminate this Agreement by
giving Grande B written notice thereof prior to the Closing, the Deposit shall
be promptly returned to Prentiss and all rights and obligations of Grande B and
Prentiss hereunder (except those set forth herein which expressly survive a
termination of this Agreement) shall terminate immediately.

                                       28
<PAGE>

         8.2 Risk of Loss. The risk of any loss or damage to the Property prior
to the recordation of the Deed shall remain upon Grande B. If any such loss or
damage occurs prior to Closing which exceeds an amount equal to five percent
(5%) of the Exchange Value, Prentiss shall have the right to terminate this
Agreement pursuant to Section 9.3 hereof. If Prentiss elects not to terminate
this Agreement pursuant to the immediately preceding sentence or a loss or
damage occurs prior to Closing which does not exceed five percent (5%) of the
Exchange Value, all insurance proceeds and rights to proceeds arising out of
such loss or damage, less the reasonable expenses incurred in collecting such
proceeds and, to the extent payable from insurance proceeds, reasonable expenses
incurred in securing the Property following a casualty, shall be paid or
assigned, as applicable, to Prentiss at Closing and Grande B shall pay Prentiss
at the Closing the amount of any deductibles under the policies of insurance
covering such loss or damage. Grande B shall be entitled to retain rent loss
insurance proceeds received that are attributable to periods prior to the
Closing Date. If Prentiss elects to terminate this Agreement pursuant to this
Section 8.2 by giving Grande B written notice thereof prior to the Closing, the
Deposit shall be promptly returned to Prentiss and all rights and obligations of
Grande B and Prentiss hereunder (except those set forth herein which expressly
survive a termination of this Agreement) shall terminate immediately.

         8.3 Broker. There is no real estate broker involved in this
transaction. Prentiss warrants and represents to Grande B that Prentiss has not
dealt with any real estate broker in connection with this transaction, nor has
Prentiss been introduced to the Property or to Grande B by any real estate
broker, and Prentiss shall indemnify Grande B and hold Grande B harmless from
and against any claims, suits, demands or liabilities of any kind or nature
whatsoever arising on account of the claim of any other person, firm or
corporation to a real estate brokerage commission or a finder's fee or a
financial advisory fee as a result of having dealt with Prentiss, or as a result
of having introduced Prentiss to Grande B or to the Property. In like manner,
Grande B warrants and represents to Prentiss that Grande B has not dealt with
any real estate broker in connection with this transaction, nor has Grande B
been introduced to Prentiss by any real estate broker, and Grande B shall
indemnify Prentiss and save and hold Prentiss harmless from and against any
claims, suits, demands or liabilities of any kind or nature whatsoever arising
on account of the claim of any person, firm or corporation to a real estate
brokerage commission or a finder's fee or a financial advisory fee as a result
of having dealt with Grande B in connection with this transaction. This
provision shall survive any termination of this Agreement and a closing of the
transaction contemplated hereby.

         8.4 Bulk Sale. It shall be the obligation of Grande B to comply with
any bulk sale requirements, statutes, laws, ordinances and regulations
promulgated with respect thereto, if any, in the State in which the Property is
located, or in or by any governmental entity having jurisdiction with respect
thereto, and to provide proof of such compliance or proof that no such
compliance is required, to Prentiss, at or prior to Closing. In any event,
Grande B shall indemnify Prentiss and save and hold Prentiss harmless from and
against any claims, suits, demands, liabilities or obligations of any kind or
nature whatsoever, including all costs of defending same, and reasonable
attorneys' fees paid or incurred in connection therewith, arising out of or
relating to any claim made by any third party or any liability asserted by any
third party that any applicable bulk sales law or like statute has not been
complied with. The provisions of this Section shall survive the Closing of the
transaction contemplated hereby.

                                       29
<PAGE>

                                  ARTICLE IX.
               LIABILITY OF PRENTISS; INDEMNIFICATION BY GRANDE B;
                           DEFAULT; TERMINATION RIGHTS

         9.1 Liability of Prentiss. Except for obligations expressly assumed or
agreed to be assumed by Prentiss hereunder, Prentiss is not assuming any
obligations of Grande B or any liability for claims arising out of any act,
omission or occurrence which occurs, accrues or arises prior to the Closing
Date, and Grande B hereby indemnifies and holds Prentiss harmless from and
against any and all claims, costs, penalties, damages, losses, liabilities and
expenses (including reasonable attorneys' fees) that may at any time be incurred
by Prentiss as a result of (a) obligations of Grande B not expressly assumed or
agreed to be assumed by Prentiss hereunder, or (b) acts, omissions or
occurrences which occur, accrue or arise prior to the Closing Date. Prentiss
hereby indemnifies and holds Grande B harmless from and against any and all
claims, costs, penalties, damages, losses, liabilities and expenses (including
reasonable attorneys' fees) that may at any time be incurred by Grande B as a
result of acts, omissions or occurrences relating to the Property arising and
accruing from and after the Closing Date. The provisions of this Section shall
survive the Closing of the transaction contemplated hereby.

         9.2 Indemnification by Grande B. Grande B hereby indemnifies and holds
Prentiss and Prentiss' officers, partners, directors, shareholders, agents and
employees (collectively, the "Indemnified Parties") harmless from and against
any and all claims, costs, penalties, damages, losses, liabilities and expenses
(including reasonable attorneys' fees) that may at any time be incurred by
Prentiss, whether incurred before or after Closing, as a result of any
inaccuracy or breach by Grande B of any of its representations, warranties,
covenants or obligations set forth herein or in any other document delivered by
Grande B pursuant hereto except for any breach or inaccuracy of any
representation or warranty as to which Grande B has given Prentiss written
notice prior to Closing of the untruth or inaccuracy or of which Prentiss
otherwise had actual knowledge prior to the Closing and nevertheless elected to
consummate the Closing; provided, however, the foregoing knowledge limitation on
Grande B's indemnity shall not limit Prentiss' remedy described in Section
9.3(a)(ii) hereof or in the last sentence of Section 9.3 hereof. The provisions
of this Section shall survive the Closing of the transaction contemplated hereby
as provided in Section 10.11 hereof, and shall, following any assignment of this
Agreement by Prentiss, continue in favor of the Indemnified Parties of the
original Prentiss hereunder as well the Indemnified Parties of any assignee
during said survival period.

         9.3 Default by Grande B/Failure of Conditions Precedent. If any
condition set forth herein for the benefit of Prentiss cannot or will not be
satisfied prior to Closing, or upon the occurrence of any other event that would
entitle Prentiss to terminate this Agreement and its obligations hereunder, and
if Grande B fails to cure any such matter or satisfy that condition within ten
(10) business days after notice thereof from Prentiss (or such other time period
as may be explicitly provided for herein), Prentiss, at its option, may elect
(a) to terminate this Agreement, in which event (i) the Deposit, less the
Independent Consideration, shall be promptly returned to Prentiss, (ii) if the
condition which has not been satisfied is a breach of a representation, warranty
or covenant known by Grande B to have been inaccurate or misleading when made,

                                       30

<PAGE>

then Grande B shall be obligated upon demand to reimburse Prentiss for Prentiss'
actual out-of-pocket inspection, financing and other costs related to Prentiss'
entering into this Agreement, inspecting the Property and preparing for a
Closing of the transaction contemplated hereby, including, without limitation,
Prentiss' attorneys' fees incurred in connection with the preparation,
negotiation and execution of this Agreement and in connection with Prentiss' due
diligence review, audits and preparation for a Closing up to an aggregate amount
equal to $100,000.00; provided, the foregoing shall not limit or include the
sums which may be payable by Grande B pursuant to Section 9.6 below, and (iii)
all other rights and obligations of Grande B and Prentiss hereunder (except
those set forth herein which expressly survive a termination of this Agreement)
shall terminate immediately; (b) elect to proceed to Closing; or (c) seek to
enforce Grande B's obligations hereunder by specific performance. If Prentiss
elects to proceed to Closing and there is either a misrepresentation or breach
of a warranty by Grande B (other than a breach of a representation or warranty
of which Prentiss had actual knowledge prior to the Closing and nevertheless
elected to consummate the Closing) or the breach of a covenant by Grande B or a
failure by Grande B to perform its obligations hereunder first discovered by
Prentiss after the Closing Date, Prentiss shall retain all remedies accruing as
a result thereof, including, but not limited to, the remedy of specific
performance of Grande B's covenants and obligations and the remedy of the
recovery of all reasonable damages resulting from Grande B's breach of warranty
or covenant. Notwithstanding the foregoing, if the condition which has not been
satisfied is a breach of one or more representations and warranties by Grande B
or Brandywine OP in this Agreement and/or in any of the other documents executed
of even date herewith among Prentiss, Grande B, Brandywine OP or any of their
respective affiliates (the "Other Documents"), Prentiss has elected to proceed
to Closing, and Prentiss can reasonably quantify the damage resulting from such
breach of representations and warranties with reasonable support for such
calculation of damages, then (i) if the aggregate damage is no greater than
$150,000.00 (the "First Threshold Level"), then Grande B shall have no
obligation to either cure such breaches of representations and warranties or pay
Prentiss at Closing in the event Prentiss elects to close the transaction
described in this Agreement and the Other Documents; (ii) if such aggregate
damage is greater than the First Threshold Level but less than $1,500,000.00,
then Grande B must prior to the Closing Date either cure such breaches of
representations and warranties to the reasonable satisfaction of Prentiss or
Grande B shall pay Prentiss at the Closing an amount equal to the actual damages
as reasonably determined by Prentiss as aforesaid, less the First Threshold
Level; and (iii) in the event the aggregate damages resulting from such breaches
of representations and warranties would exceed $1,500,000.00, then Prentiss may
either (A) terminate this Agreement and the Other Documents, in which event the
Deposit (less the Independent Consideration) shall be promptly refunded, or (B)
Prentiss may close the transaction as described in this Agreement and the other
Transaction Documents and Prentiss shall be paid by Grande B and Brandywine OP
the amount of $1,350,000.00, which amount shall be the maximum aggregate amount
payable by Grande B and Brandywine OP under the last sentence of Section 9.3 of
this Agreement and all of the Other Documents.

                                       31
<PAGE>

         9.4 Indemnification by Prentiss. Prentiss hereby indemnifies and holds
Grande B harmless from and against any and all claims, costs, penalties,
damages, losses, liabilities and expenses (including reasonable attorneys' fees)
that may at any time be incurred by Grande B, whether incurred before or after
Closing, as a result of any inaccuracy or breach by Prentiss of any of its
representations, warranties, covenants or obligations set forth herein or in any
other document delivered by Prentiss pursuant hereto except for any breach or
inaccuracy of any representation or warranty as to which Prentiss has given
Grande B written notice prior to Closing of the untruth or inaccuracy or of
which Grande B otherwise had actual knowledge prior to the Closing and
nevertheless elected to consummate the Closing. The provisions of this Section
shall survive the Closing of the transaction contemplated hereby for the period
described in Section 10.11 hereof.

         9.5 Default by Prentiss/Failure of Conditions Precedent. If any
condition set forth herein for the benefit of Grande B (other than a default by
Prentiss) cannot or will not be satisfied prior to Closing, and if Prentiss
fails to satisfy that condition within ten (10) business days after notice
thereof from Grande B (or such other time period as may be explicitly provided
for herein), Grande B may, at its option, elect either (a) to terminate this
Agreement in which event the Deposit shall be promptly returned to Prentiss and
the parties hereto shall be released from all further obligations hereunder
except those which expressly survive a termination of this Agreement, or (b) to
waive its right to terminate, and instead, to proceed to Closing. If, prior to
Closing, Prentiss defaults in performing any of its obligations under this
Agreement (including its obligation to purchase the Property), and Prentiss
fails to cure any such default within ten (10) business days after notice
thereof from Grande B, then Grande B's sole remedy for such default shall be
either (i) to terminate this Agreement and retain the Deposit or (ii) to pursue
the remedy of specific performance compelling Prentiss to acquire the Property
pursuant to the provisions of this Agreement.

         9.6 Costs and Attorneys' Fees. In the event of any litigation or
dispute between the parties arising out of or in any way connected with this
Agreement, resulting in any litigation, then the prevailing party in such
litigation shall be entitled to recover its costs of prosecuting and/or
defending same, including, without limitation, reasonable attorneys' fees at
trial and all appellate levels. The provisions of this Section shall survive the
Closing of the transaction contemplated hereby.

         9.7 Limitation of Liability. Notwithstanding anything herein to the
contrary, except in the case of fraud by either party, the liability of each
party hereto resulting from the breach or default by either party shall be
limited to actual damages incurred by the injured party and except in the case
of fraud by either party, the parties hereto hereby waive their rights to
recover from the other party consequential, punitive, exemplary, and speculative
damages. The provisions of this Section 9.7 shall survive the Closing of the
transaction contemplated hereby.

                                   ARTICLE X.
                            MISCELLANEOUS PROVISIONS

         10.1 Completeness; Modification. This Agreement and the Second Exchange
Agreement constitute the entire agreement between the parties hereto with
respect to the transactions contemplated hereby and supersedes all prior
discussions, understandings, agreements and negotiations between the parties
hereto. This Agreement may be modified only by a written instrument duly
executed by the parties hereto. Any waiver of rights under this Agreement shall
be effective only if in writing and duly executed and delivered by the party
against whom such waiver is asserted.

                                       32
<PAGE>

         10.2 Assignments. Prentiss may assign its rights hereunder without the
consent of Grande B to any affiliate of Prentiss, in which event, except as
otherwise specified herein, such assignee shall be the "Prentiss" hereunder;
however, any such assignment shall not relieve the original Prentiss of its
obligations under this Agreement, including specifically the obligation to close
the purchase of the Property in accordance with this Agreement as though there
were no assignment.

         10.3 Successors and Assigns. This Agreement shall bind and inure to the
benefit of the parties hereto and their respective successors and assigns.

         10.4 Days. If any action is required to be performed, or if any notice,
consent or other communication is given, on a day that is a Saturday or Sunday
or a legal holiday in the jurisdiction in which the action is required to be
performed or in which is located the intended recipient of such notice, consent
or other communication, such performance shall be deemed to be required, and
such notice, consent or other communication shall be deemed to be given, on the
first business day following such Saturday, Sunday or legal holiday. Unless
otherwise specified herein, all references herein to a "day" or "days" shall
refer to calendar days and not business days.

         10.5 Governing Law. This Agreement and all documents referred to herein
shall be governed by and construed and interpreted in accordance with the laws
of the State of Delaware.

         10.6 Counterparts. To facilitate execution, this Agreement may be
executed in as many counterparts as may be required. It shall not be necessary
that the signature on behalf of both parties hereto appear on each counterpart
hereof. All counterparts hereof shall collectively constitute a single
agreement.

         10.7 Severability. If any term, covenant or condition of this
Agreement, or the application thereof to any person or circumstance, shall to
any extent be invalid or unenforceable, the remainder of this Agreement, or the
application of such term, covenant or condition to other persons or
circumstances, shall not be affected thereby, and each term, covenant or
condition of this Agreement shall be valid and enforceable to the fullest extent
permitted by law.

         10.8 Notices. All notices, requests, demands and other communications
hereunder shall be in writing and shall be delivered by hand, transmitted by
facsimile transmission, sent prepaid by Federal Express (or a comparable
overnight delivery service) or sent by the United States mail, certified,
postage prepaid, return receipt requested, at the addresses and with such copies
as designated below. Any notice, request, demand or other communication
delivered or sent in the manner aforesaid shall be deemed given or made (as the
case may be) when actually delivered to the intended recipient.

         If to Grande B: Brandywine Realty Trust
                         14 Campus Boulevard, Suite 100
                         Newtown Square, PA  19073-3780
                         Attn: Brad A. Molotsky, General Counsel
                         Fax No.: 610-325-4628

                                       33
<PAGE>

         If to Prentiss:      Prentiss Properties Acquisition Partners, L.P.
                              3860 West Northwest Highway, Suite 400
                              Dallas, Texas  75220
                              Attn.: J. Kevan Dilbeck, General Counsel
                              Fax No.: (214) 350-2409

         With a copy to:      Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                              1700 Pacific Avenue, Suite 4100
                              Dallas, Texas  75201-4675
                              Attn.:  Randall M. Ratner, P.C.
                              Fax No.:  (214) 969-4343

         If to Escrow Agent:  Chicago Title Insurance Company
                              2001 Bryan Street, Suite 1700
                              Dallas, Texas  75201
                              Attn.:  Ellen Schwab
                              Fax No.:  (214) 965-1629

or to such other address as the intended recipient may have specified in a
notice to the other party. Any party hereto may change its address or designate
different or other persons or entities to receive copies by notifying the other
party and Escrow Agent in a manner described in this Section.

         10.9 Escrow Agent. Escrow Agent referred to in the definition thereof
contained in Section 1.1 hereof has agreed to act as such for the convenience of
the parties without fee or other charges for such services as Escrow Agent.
Escrow Agent shall not be liable: (a) to any of the parties for any act or
omission to act except for its own willful misconduct; (b) for any legal effect,
insufficiency, or undesirability of any instrument deposited with or delivered
by Escrow Agent or exchanged by the parties hereunder, whether or not Escrow
Agent prepared such instrument; (c) for any loss or impairment of funds that
have been deposited in escrow while those funds are in the course of collection,
or while those funds are on deposit in a financial institution, if such loss or
impairment results from the failure, insolvency or suspension of a financial
institution; (d) for the expiration of any time limit or other consequence of
delay, unless a properly executed written instruction, accepted by Escrow Agent,
has instructed Escrow Agent to comply with said time limit; or (e) for the
default, error, action or omission of either party to the escrow. Escrow Agent,
in its capacity as escrow agent, shall be entitled to rely on any document or
paper received by it, believed by such Escrow Agent, in good faith, to be bona
fide and genuine. In the event of any dispute as to the disposition of the
Deposit or any other monies held in escrow, or of any documents held in escrow,
Escrow Agent may, if such Escrow Agent so elects, interplead the matter by
filing an interpleader action in a court of general jurisdiction in the county
or circuit where the Real Property is located (to the jurisdiction of which both
parties do hereby consent), and pay into the registry of the court the Deposit,
or deposit any such documents with respect to which there is a dispute in the
Registry of such court, whereupon such Escrow Agent shall be relieved and
released from any further liability as Escrow Agent hereunder. Escrow Agent
shall not be liable for Escrow Agent's compliance with any legal process,
subpoena, writ, order, judgment and decree of any court, whether issued with or
without jurisdiction, and whether or not subsequently vacated, modified, set
aside or reversed.

                                       34
<PAGE>

         10.10 Incorporation by Reference. All of the exhibits attached hereto
are by this reference incorporated herein and made a part hereof.

         10.11 Survival. All of the representations, warranties, covenants and
agreements of Grande B and Prentiss made in, or pursuant to, this Agreement
shall survive Closing through the period ending twelve (12) months thereafter
and shall not merge into the Deed or any other document or instrument executed
and delivered in connection herewith; provided, however, the covenants in the
last sentence of Section 2.4(b) and Section 7.6 shall survive for the time
period described in such Sections, and the covenants in Sections 6.6 and 7.8 and
the indemnities in this Agreement shall have an unlimited survival period. In
the event a claim for indemnity is asserted in good faith prior to the
expiration of the applicable survival period, the claim may be asserted and the
indemnity shall continue notwithstanding the expiration of the survival period.

         10.12 Further Assurances. Grande B and Prentiss each covenant and agree
to sign, execute and deliver, or cause to be signed, executed and delivered, and
to do or make, or cause to be done or made, upon the written request of the
other party, any and all agreements, instruments, papers, deeds, acts or things,
supplemental, confirmatory or otherwise, as may be reasonably required by either
party hereto for the purpose of or in connection with consummating the
transactions described herein. Grande B agrees to promptly correct any defect,
error or omission which may be discovered in the contents of this Agreement or
in any of the Exhibits or Schedules hereto.

         10.13 No Partnership. This Agreement does not and shall not be
construed to create a partnership, joint venture or any other relationship
between the parties hereto except the relationship of Grande B and Prentiss
specifically established hereby.

         10.14 Time of Essence. Time is of the essence with respect to every
provision hereof.

         10.15 Signatory Exculpation. The signatory(ies) for Prentiss, Grande B
and Brandywine OP are executing this Agreement in his/their capacity as
representative of Prentiss, Grande B and Brandywine OP, respectively, and not
individually and, therefore, shall have no personal or individual liability of
any kind in connection with this Agreement and the transactions contemplated by
it. No recourse shall be had for any obligation of Prentiss, Grande B or
Brandywine OP under this Agreement or under any document executed in connection
herewith or pursuant hereto, or for any claim based thereon or otherwise in
respect thereof, against any past, present or future trustee, shareholder,
officer or employee of Brandywine Realty Trust, Prentiss Properties Trust,
Prentiss, Grande B or Brandywine OP, whether by virtue of any statute or rule of
law, or by the enforcement of any assessment or penalty or otherwise, all such
liability being expressly waived and released by the parties hereto and all
parties claiming by, through or under them.

         10.16 Rules of Construction. The following rules shall apply to the
construction and interpretation of this Agreement:

             (a) Singular words shall connote the plural number as well as the
singular and vice versa, and the masculine shall include the feminine and the
neuter.

                                       35
<PAGE>

             (b) All references herein to particular articles, sections,
subsections, clauses or exhibits are references to articles, sections,
subsections, clauses or exhibits of this Agreement.

             (c) The table of contents and headings contained herein are solely
for convenience of reference and shall not constitute a part of this Agreement
nor shall they affect its meaning, construction or effect.

             (d) Each party hereto and its counsel have reviewed and revised (or
requested revisions of) this Agreement and have participated in the preparation
of this Agreement, and therefore any usual rules of construction requiring that
ambiguities are to be resolved against a particular party shall not be
applicable in the construction and interpretation of this Agreement or any
exhibits hereto.

             (e) As used herein, the term or phrases "Effective Date," "date of
this Agreement" or "date hereof" shall mean the first date Escrow Agent is in
receipt of this Agreement executed by Grande B and Prentiss.

         10.17 Like-Kind Exchange. Grande B agrees to cooperate reasonably with
Prentiss in effecting an exchange transaction which includes the Property,
pursuant to Section 1031 of the United States Internal Revenue Code, provided
that any such exchange transaction, and the related documentation, shall: (a) be
at the sole cost and expense of Prentiss; (b) not require Grande B to execute
any contract, make any commitment, or incur any obligations, contingent or
otherwise, to third parties; (c) not delay the Closing; (d) not include Grande B
becoming involved in a transaction with a third party; and (e) not otherwise be
contrary to or inconsistent with the terms of this Agreement.

         10.18 SEC Reporting (8-K) Requirements. For the period of time
commencing on the date hereof and continuing through the second anniversary of
the Closing Date, and without limitation of other document production otherwise
required of Grande B hereunder, Grande B shall, from time to time, upon
reasonable advance written notice from Prentiss, provide Prentiss and its
representatives, with access to all financial and other information pertaining
to the period of Grande B's ownership and operation of the Property, which
information is relevant and reasonably necessary, in the opinion of outside,
third party accountants (the "Accountants") for Prentiss, to enable Prentiss and
its Accountants to prepare financial statements in compliance with any or all of
(a) Rule 3-05 or 3-14 of Regulation S-X of the Securities and Exchange
Commission (the "Commission"), as applicable; (b) any other rule issued by the
Commission and applicable to Prentiss or Prentiss Properties Trust ("PPT"); and
(c) any registration statement, report or disclosure statement filed with the
Commission by PPT; and a representation letter, signed by the individual(s)
responsible for Grande B's financial reporting, as prescribed by generally
accepted auditing standards promulgated by the Auditing Standards Division of
the American Institute of Certified Public Accountants, which representation
letter may be required by the Accountants in order to render an opinion
concerning Prentiss' or PPT's financial statements.

                                       36
<PAGE>

         IN WITNESS WHEREOF, Grande B and Prentiss have caused this Agreement to
be executed in their names by their respective duly authorized representatives.

                          GRANDE B:

                          BRANDYWINE GRANDE B, L.P., a Delaware
                          limited partnership

                          By:      BRANDYWINE GRANDE B CORP., a
                                   Delaware corporation, its general partner

                                   By:   /s/ Gerard H. Sweeney
                                         --------------------------------------
                                   Title: President and Chief Executive Officer
                                          -------------------------------------

                                   Date of Execution: March 14, 2001

                          PRENTISS:

                          PRENTISS PROPERTIES ACQUISITION
                          PARTNERS, L.P., a Delaware limited partnership

                          By:      Prentiss Properties I, Inc., a  Delaware
                                   corporation, its general partner

                                   By:   /s/ Thomas F. August
                                         --------------------------------------
                                   Title: President and Chief Executive Officer
                                          -------------------------------------

                                   Date of Execution: March 14, 2001

         Brandywine OP is executing this Agreement for the purpose of (a)
consenting to the provisions of Sections 3.1 and 6.4 of this Agreement, and (b)
agreeing to guaranty all indemnities of Grande B in this Agreement and all
documents executed in connection with this Agreement.

                          BRANDYWINE OPERATING PARTNERSHIP, L.P.

                          By:      Brandywine Realty Trust, its general partner

                                   By:   /s/ Gerard H. Sweeney
                                         --------------------------------------
                                   Title: President and Chief Executive Officer
                                          -------------------------------------

                                       37
<PAGE>

                             RECEIPT OF ESCROW AGENT

         Chicago Title Insurance Company, as Escrow Agent, acknowledges receipt
of the sum of $700,050.00 by wire transfer, from Prentiss as described in
Section 2.3 of the foregoing Exchange Agreement, said wire transfer to be held
pursuant to the terms and provisions of said Agreement.

         DATED this _____ day of __________, 2001.

                                      CHICAGO TITLE INSURANCE COMPANY

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

                                       38<PAGE>

      Exhibit 10.2 - Exchange Agreement (Pennsylvania/New Jersey Properties)

                               EXCHANGE AGREEMENT

                                     between

                 PRENTISS PROPERTIES ACQUISITION PARTNERS, L.P.,
                         a Delaware limited partnership

                                  ("Prentiss")

                                       and

                           BRANDYWINE GRANDE B, L.P.,
                         a Delaware limited partnership

                                  ("Grande B")

<PAGE>

                                TABLE OF CONTENTS

                                                                            Page

ARTICLE I. DEFINITIONS.........................................................1
1.1    Definitions.............................................................1
ARTICLE II. EXCHANGE OF PROPERTY;  DEPOSIT;  EXCHANGE VALUE; STUDY PERIOD;
CONVEYANCE SUBJECT TO EXISTING NOTES AND
LIENS..........................................................................8
2.1    Exchange Property.......................................................8
2.2    Exchange Value; Conveyance Subject to Existing Notes and Liens..........8
2.3    Deposit.................................................................8
2.4    Study Period............................................................9
ARTICLE III. PRENTISS' REPRESENTATIONS AND WARRANTIES.........................13
3.1    Organization and Power.................................................13
3.2    Authorization, Execution and Disclosure................................13
3.3    Non-contravention......................................................14
3.4    No Special Taxes.......................................................14
3.5    Compliance with Existing Laws and Restrictive Covenants................14
3.6    Personal Property......................................................14
3.7    Operating Agreements...................................................14
3.8    Condemnation Proceedings; Roadways.....................................15
3.9    Actions or Proceedings.................................................15
3.10   Bankruptcy.............................................................15
3.11   Hazardous Substances...................................................15
3.12   Parties in Possession..................................................16
3.13   Leases.................................................................16
3.14   Leased Property........................................................16
3.15   No Unpaid Charges......................................................16
3.16   Condition of Improvements..............................................16
3.17   Access.................................................................17
3.18   No Commitments.........................................................17
3.19   Prentiss Is Not a "Foreign Person".....................................17
3.20   Leasing Commissions....................................................17
3.21   Other Agreements.......................................................17
3.22   Existing Secured Indebtedness..........................................17
3.23   Employment on "At-Will" Basis..........................................17
3.24   Ground Lease...........................................................18
3.25   LIMITATIONS ON REPRESENTATIONS AND WARRANTIES..........................18
ARTICLE IV. GRANDE B'S REPRESENTATIONS AND WARRANTIES.........................19
4.1    Organization and Power.................................................19
4.2    Non-contravention......................................................20
4.3    Litigation.............................................................20
4.4    Bankruptcy.............................................................20
4.5    Authorization, Execution and Disclosure................................20
ARTICLE V. CONDITIONS PRECEDENT...............................................20
5.1    As to Grande B's Obligations...........................................20
5.2    As to Prentiss' Obligations............................................22

                                       i
<PAGE>

ARTICLE VI. COVENANTS OF PRENTISS.............................................22
6.1    Operating Agreements...................................................23
6.2    Warranties and Guaranties..............................................23
6.3    Insurance..............................................................23
6.4    Operation of Property Prior to Closing.................................23
6.5    No Marketing...........................................................25
6.6    Leased Property........................................................25
ARTICLE VII. CLOSING..........................................................25
7.1    Closing................................................................25
7.2    Prentiss' Deliveries...................................................26
7.3    Grande B's Deliveries..................................................28
7.4    Mutual Deliveries......................................................28
7.5    Closing Costs..........................................................28
7.6    Revenue and Expense Allocations........................................29
7.7    Delinquent Rents.......................................................30
7.8    Costs Associated with Certain Leasing Activities.......................30
ARTICLE VIII. GENERAL PROVISIONS..............................................31
8.1    Condemnation...........................................................31
8.2    Risk of Loss...........................................................31
8.3    Broker.................................................................32
8.4    Bulk Sale..............................................................32
ARTICLE IX. LIABILITY OF GRANDE B; INDEMNIFICATION BY PRENTISS;
DEFAULT; TERMINATION RIGHTS......................32
9.1    Liability of Grande B..................................................32
9.2    Indemnification by Prentiss............................................33
9.3    Default by Prentiss/Failure of Conditions Precedent....................33
9.4    Indemnification by Grande B............................................34
9.5    Default by Grande B/Failure of Conditions Precedent....................34
9.6    Costs and Attorneys' Fees..............................................35
9.7    Limitation of Liability................................................35
ARTICLE X. MISCELLANEOUS PROVISIONS...........................................35
10.1   Completeness; Modification.............................................35
10.2   Assignments............................................................35
10.3   Successors and Assigns.................................................35
10.4   Days...................................................................35
10.5   Governing Law..........................................................36
10.6   Counterparts...........................................................36
10.7   Severability...........................................................36
10.8   Notices................................................................36
10.9   Escrow Agent...........................................................37
10.10  Incorporation by Reference.............................................37
10.11  Survival...............................................................37
10.12  Further Assurances.....................................................37
10.13  No Partnership.........................................................38
10.14  Time of Essence........................................................38
10.15  Signatory Exculpation..................................................38
10.16  Rules of Construction..................................................38
10.17  Like-Kind Exchange.....................................................39
10.18  SEC Reporting (8-K) Requirements.......................................39

                                       ii
<PAGE>

EXHIBITS
Exhibit A -       Land
Exhibit B -       Exchange Property
Exhibit C -       Tenant's Estoppel Certificate
Exhibit D -       Excluded Tangible Personal Property
Exhibit E -       Existing Notes and Existing Liens
Exhibit F -       Form of Lender Estoppel Certificate
Exhibit G -       Description of Ground Leases

SCHEDULES
Schedule 3.7      Operating Agreements
Schedule 3.13     Rent Roll and Accounts Receivable Report
Schedule 3.20     Outstanding Leasing Commissions
Schedule 6.4(g)   Approved New Leases

                                      iii
<PAGE>

                               EXCHANGE AGREEMENT

         THIS EXCHANGE AGREEMENT (this "Agreement") is made as of this 14th day
of March, 2001, between PRENTISS PROPERTIES ACQUISITION PARTNERS, L.P., a
Delaware limited partnership and/or assigns (collectively, "Prentiss"), and
BRANDYWINE GRANDE B, L.P., a Delaware limited partnership ("Grande B").

                             R E C I T A T I O N S:

         A. Prentiss is the owner of a fee estate in certain real properties
located in the Commonwealth of Pennsylvania and States of Delaware and New
Jersey, as more particularly identified on Exhibit A-1, attached hereto and made
a part hereof for all purposes and the owner of a leasehold estate in certain
real properties located in the Commonwealth of Pennsylvania, as more
particularly identified on Exhibit A-2 hereto and made a part hereof for all
purposes.

         B. Grande B is desirous of acquiring such property from Prentiss and
Prentiss is desirous of conveying such property to Grande B, upon the terms and
conditions hereinafter set forth, in exchange for the conveyance of certain
property by Grande B to Prentiss in accordance with an Exchange Agreement of
even date herewith between Prentiss and Grande B (the "Second Exchange
Agreement").

         NOW, THEREFORE, in consideration of the foregoing premises and in
consideration of the mutual covenants, promises and undertakings of the parties
hereinafter set forth, and for other good and valuable consideration, the
receipt and sufficiency of which is hereby acknowledged by the parties, it is
agreed:

                                   ARTICLE I.
                                   DEFINITIONS

         1.1   Definitions. The following terms shall have the indicated
meanings:

               "Act of Bankruptcy" shall mean if a party hereto or any general
partner thereof shall (a) apply for or consent to the appointment of, or the
taking of possession by, a receiver, custodian, trustee or liquidator of itself
or of all or a substantial part of its property, (b) admit in writing its
inability to pay its debts as they become due, (c) make a general assignment for
the benefit of its creditors, (d) file a voluntary petition or commence a
voluntary case or proceeding under the Federal Bankruptcy Code (as now or
hereafter in effect), (e) be adjudicated a bankrupt or insolvent, (f) file a
petition seeking to take advantage of any other law relating to bankruptcy,
insolvency, reorganization, winding-up or composition or adjustment of debts,
(g) fail to controvert in a timely and appropriate manner, or acquiesce in
writing to, any petition filed against it in an involuntary case or proceeding
under the Federal Bankruptcy Code (as now or hereafter in effect), or (h) take
any corporate or partnership action for the purpose of effecting any of the
foregoing; or if a proceeding or case shall be commenced, without the
application or consent of a party hereto or any general partner thereof, in any
court of competent jurisdiction seeking (1) the liquidation, reorganization,
dissolution or winding-up, or the composition or readjustment of debts, of such
party or general partner, (2) the appointment of a receiver, custodian, trustee

                                       1
<PAGE>

or liquidator for such party or general partner or all or any substantial part
of its assets, or (3) other similar relief under any law relating to bankruptcy,
insolvency, reorganization, winding-up or composition or adjustment of debts,
and such proceeding or case shall continue undismissed for a period of ninety
(90) consecutive days; or an order (including an order for relief entered in an
involuntary case under the Federal Bankruptcy Code, as now or hereafter in
effect) judgment or decree approving or ordering any of the foregoing shall be
entered and continue unstayed and in effect, for a period of ninety (90)
consecutive days.

               "Applicable Laws" shall mean any applicable building, zoning,
subdivision, environmental, health, safety or other governmental laws, statutes,
ordinances, resolutions, rules, codes, regulations, orders or determinations of
any Governmental Authority or of any insurance boards of underwriters (or other
body exercising similar functions), or any restrictive covenants or deed
restrictions affecting the Property or the ownership, operation, use,
maintenance or condition thereof.

               "Assignment and Assumption Agreement" shall mean one or more
assignment and assumption agreements whereby, subject to the allocation
provisions in Section 7.8 hereof, (a) Prentiss (1) assigns and Grande B assumes
the Assumed Operating Agreements, (2) assigns all of Prentiss' right, title and
interest in and to the Intangible Personal Property, to the extent assignable,
and (3) indemnifies, defends and holds Grande B and its agents, employees,
officers, directors, shareholders and contractors harmless with respect to all
defaults, liabilities, claims, costs and expenses (including, without
limitation, reasonable attorneys' fees) relating to acts or omissions accruing
under such Assumed Operating Agreements before the Closing Date; and (b) Grande
B indemnifies, defends and holds Prentiss harmless with respect to all defaults,
liabilities, claims, costs and expenses (including, without limitation,
reasonable attorneys' fees) relating to acts or omissions accruing under such
Assumed Operating Agreements after the Closing Date.

               "Assignment of Ground Lease" shall mean one or more assignment
and assumption agreements whereby (a) Prentiss assigns to Grande B and Grande B
assumes each Ground Lease, and (b) (1) Prentiss indemnifies, defends and holds
Grande B harmless with respect to all liabilities, claims, costs and expenses
(including, without limitation, reasonable attorneys' fees) arising out of
defaults by Prentiss under each Ground Lease accruing or occurring before the
Closing Date, and (2) Grande B indemnifies, defends and holds Prentiss harmless
with respect to all liabilities, claims, costs and expenses (including, without
limitation, reasonable attorneys' fees) arising out of defaults by Grande B
accruing and occurring from and after the Closing Date.

               "Assignment of Leases" shall mean the assignment agreement, in
recordable form, whereby, subject to the allocation provisions in Section 7.8
hereof, (a) Prentiss (1) assigns and Grande B assumes all of Prentiss' right,
title and interest in and to the Leases, and (2) indemnifies, defends and holds
Grande B and its agents, employees, officers, directors, shareholders and
contractors harmless with respect to all defaults, liabilities, claims, costs
and expenses (including, without limitation, reasonable attorneys' fees)

                                       2
<PAGE>

relating to acts or omissions accruing under such Leases before the Closing
Date; and (b) Grande B indemnifies, defends and holds Prentiss harmless with
respect to all defaults, liabilities, claims, costs and expenses (including,
without limitation, reasonable attorneys' fees) relating to acts or omissions
accruing under such Leases after the Closing Date.

         "Assumed Operating Agreements" shall mean the Operating Agreements
listed on Schedule 3.7 hereto which are not to be terminated pursuant to the
last sentence of Section 3.7 hereof.

               "Authorizations" shall mean all licenses, permits and approvals
required by any governmental or quasi-governmental agency, body, department,
commission, board, bureau, instrumentality or officer, any owners association
created pursuant to deed restrictions affecting the Real Property or otherwise
appropriate with respect to the construction, ownership, operation, leasing,
maintenance, or use of the Property or any part thereof.

               "Bill of Sale - Personal Property" shall mean one or more bills
of sale conveying title to the Tangible Personal Property and the Intangible
Personal Property from Prentiss to Grande B.

               "Brandywine OP" shall mean Brandywine Operating Partnership,
L.P., a Delaware limited partnership, which is the owner, as a limited partner,
of a ninety-nine percent (99%) limited partnership interest in Grande B.

               "Closing" shall mean the Closing of the conveyance of the
Property pursuant to this Agreement and shall be deemed to occur on the Closing
Date.

               "Closing Date" shall mean the date on which the Closing occurs.

               "Closing Documents" shall mean the documents defined as such in
Section 7.1 hereof.

               "Deeds" shall mean those certain special warranty deeds conveying
title to each of the Parcels and subject only to Permitted Title Exceptions
affecting each such Parcel. If there is any difference between the description
of any portion of the Fee Estate Land constituting a Parcel as shown on Exhibit
A-1 attached hereto and the description of the applicable Parcel as shown on the
Survey, the description of the applicable Parcel to be contained in the
applicable Deed and the description of such Parcel set forth in the Title
Commitment shall conform to the description shown on the Survey.

               "Deposit" shall mean all amounts deposited from time to time with
Escrow Agent by Grande B pursuant to Section 2.3 hereof, plus all interest or
other earnings that may accrue thereon. All cash Deposits shall be invested by
Escrow Agent in a commercial bank or banks acceptable to Grande B at money
market rates, or in such other investments as shall be approved in writing by
Prentiss and Grande B. The Deposit shall be held and disbursed by Escrow Agent
in strict accordance with the terms and provisions of this Agreement.

               "Environmental Damages" shall mean all third-party claims,
judgments, damages, losses, penalties, fines, liabilities (including, without
limitation, punitive damages and strict liability), encumbrances, liens, costs
and expenses of investigation and defense of any claim, whether or not such is
ultimately defeated, and of any settlement or judgment, of whatever kind or

                                       3
<PAGE>

nature, contingent or otherwise, matured or unmatured, including, without
limitation, attorneys' fees and disbursements and consultants' fees, any of
which arise as a result of the existence of Hazardous Materials upon, about or
beneath the Property or migrating or threatening to migrate from the Property,
or as a result of the existence of a violation of Environmental Requirements
pertaining to the Property.

               "Environmental Requirements" shall mean (i) all applicable
statutes, regulations, rules, policies, ordinances, codes, licenses, permits,
orders, approvals, plans, authorizations, and similar items, of all Governmental
Authorities, and (ii) all judicial, administrative and regulatory decrees,
judgments and orders, in each case of (i) and (ii) relating to the protection of
human health or the environment from Hazardous Materials and health and safety
of employees or the public from Hazardous Materials, including, without
limitation, all requirements thereof pertaining to reporting, licensing,
permitting, investigation and remediation of emissions, discharges, releases or
threatened releases of Hazardous Materials into the air, surface water,
groundwater or land, or relating to the manufacture, processing, distribution,
use, treatment, storage, disposal, transport or handling of Hazardous Materials.

               "Escrow Agent" shall mean Chicago Title Insurance Company, whose
address is 2001 Bryan Street, Suite 1700, Dallas, Texas 75201, Attention: Ellen
Schwab.

               "Exchange Property" shall mean the real property and improvements
thereon to be conveyed by Grande B to Prentiss pursuant to the Second Exchange
Agreement, which real property is described on Exhibit B hereto.

               "Exchange Value" shall mean $107,200,000.00 to be allocated among
the Real Property as provided in Section 2.2 hereof.

               "Existing Liens" shall mean the deed(s) of trust, mortgage(s),
assignments of leases, indemnities, loan agreements and other security
instruments securing, evidencing or executed in connection with the Existing
Notes described on Exhibit E hereto.

               "Existing Notes" shall mean the promissory notes described on
Exhibit E hereto.

               "Fee Estate Land" shall mean those certain parcels of real estate
lying and being in the States of Delaware and New Jersey and the Commonwealth of
Pennsylvania, as more particularly described on Exhibit A-1 attached hereto,
together with all easements, rights, privileges, remainders, reversions and
appurtenances thereunto belonging or in any way appertaining, and all of the
estate, right, title, interest, claim or demand whatsoever of Prentiss therein,
in the streets and ways adjacent thereto and in the beds thereof, either at law
or in equity, in possession or expectancy, now or hereafter acquired.

               "FIRPTA Certificate" shall mean the affidavit of Prentiss under
Section 1445 of the Internal Revenue Code, as amended, certifying that Prentiss
is not a foreign corporation, foreign partnership, foreign trust, foreign estate
or foreign person (as those terms are defined in the Internal Revenue Code and
regulations promulgated thereunder), in form and substance satisfactory to
Grande B.

                                       4
<PAGE>

               "Governmental Authority" shall mean any federal, state, county,
municipal or other government or any governmental or quasi-governmental agency,
department, commission, board, bureau, officer or instrumentality, foreign or
domestic, or any of them.

               "Grande B's Objections" shall mean the objections defined as such
in Section 2.4(d) hereof.

               "Grande B's Organizational Documents" shall mean the
organizational documents and all amendments thereto of Grande B.

               "Ground Lease" shall mean each existing ground lease, and all
amendments thereto, under which Prentiss leases the Leasehold Estate Land, as
identified on Exhibit A-2 hereto.

               "Ground Lessor" shall mean each lessor under each Ground Lease.

               "Hazardous Materials" shall mean any chemical substance: (i)
which is or becomes defined as a "hazardous substance," "hazardous waste,"
"hazardous material," "pollutant," "contaminant," or "toxic," "explosive,"
"corrosive," "flammable," "infectious," "radioactive," "carcinogenic," or
"mutagenic" material under any law, regulation, rule, order, or other authority
of the federal, state or local governments, or any agency, department,
commission, board, or instrumentality thereof, regarding the protection of human
health or the environment from such chemical substances including, but not
limited to, the following federal laws and their amendments, analogous state and
local laws, and any regulations promulgated thereunder: the Clean Air Act, the
Clean Water Act, the Oil Pollution Control Act, the Comprehensive Environmental
Response, Compensation, and Liability Act of 1986, the Emergency Planning and
Community Right to Know Act, the Solid Waste Disposal Act, the Resource
Conservation and Recovery Act, the Safe Drinking Water Act, the Federal
Insecticide, Fungicide and Rodenticide Act, and the Toxic Substances Control
Act, including, without limitation, asbestos and gasoline and other petroleum
products (including crude oil or any fraction thereof); (ii) without limitation,
which contains gasoline, diesel fuel or other petroleum hydrocarbons; (iii)
without limitation, which contains asbestos-containing materials or urea
formaldehyde foam insulation; or (iv) without limitation, radon gas; provided,
however, the term "Hazardous Materials" shall not include de minimis quantities
of substances of kinds and in amounts ordinarily and customarily used or stored
in properties similar to the Property for the purposes of cleaning or other
maintenance or operations and otherwise in compliance with Environmental
Requirements.

         "Improvements" shall mean all buildings, improvements, fixtures and
other items of real estate located on the various Parcels and portions of the
Leasehold Estate Land which constitute the Land.

               "Insurance Policies" shall mean all policies of insurance
maintained by or on behalf of Prentiss pertaining to the Property, its
operation, or any part thereof.

               "Intangible Personal Property" shall mean all intangible personal
property owned or possessed by Prentiss and used in connection with the
ownership, operation, leasing, occupancy or maintenance of the Property,
including, without limitation, (1) Prentiss' exclusive right to use any trade

                                       5
<PAGE>

names associated with the Property and all variations thereof (other than
variants of Prentiss' legal name, all rights to which shall be retained by
Prentiss), (2) the Authorizations, (3) escrow accounts (subject to the
provisions of Section 7.6 hereof), utility and development rights and
privileges, general intangibles, business records, plans and specifications
pertaining to the Real Property and the Personal Property, and (4) any unpaid
award for taking by condemnation or any damage to the Land by reason of a change
of grade or location of or access to any street or highway.

               "Land" shall mean the Fee Estate Land and the Leasehold Estate
Land.

               "Leased Property" shall mean all leased items of personal
property.

               "Leasehold Estate Land" shall mean each parcel of real estate
which is subject to a Ground Lease, situate in the Commonwealth of Pennsylvania,
as more particularly described on Exhibit A-2 attached hereto, together with all
easements, rights, privileges, remainders, reversions and appurtenances
thereunto belonging or in any way appertaining, and all of the estate, right,
title, interest, claim or demand whatsoever of Prentiss therein, in the streets
and ways adjacent thereto and in the beds thereof, either at law or in equity,
in possession or expectancy, now or hereafter acquired.

               "Leases" shall mean all leases, tenancies and other rights of
occupancy or use for any portion of the Real Property and leasehold estate,
together with any and all amendments thereto; provided, the Leases shall not
include any Ground Lease.

               "Operating Agreements" shall mean all management, service, supply
and maintenance contracts, if any, in effect with respect to the Property and
all other contracts (other than the Leases) that affect the Property or are
otherwise related to the construction, ownership, operation, occupancy or
maintenance of the Property.

               "Owner's Title Policy" shall mean an owner's policy of title
insurance for the Fee Estate Land and a leasehold policy of title insurance for
the Leasehold Estate Land issued to Grande B by the Title Company, pursuant to
which the Title Company insures Grande B's ownership of fee simple title to the
Fee Estate Land and leasehold title to the Leasehold Estate Land subject only to
Permitted Title Exceptions. The Owner's Title Policy shall insure Grande B in
the aggregate amount of $107,200,000.00 and shall be acceptable in form and
substance to Grande B. Grande B may require such deletions of standard
exceptions and such title endorsements as are legally available and customarily
required by institutional investors purchasing property comparable to the
Property in each State where the Property is situated. The description of the
Land in the Owner's Title Policy shall be by courses and distances or by
reference to a legal, subdivided lot and shall be identical to the description
shown on the Survey.

               "Parcel" shall mean each individual tract of the Fee Estate Land
described on Exhibit A-1 hereto.

               "Permitted Title Exceptions" shall mean each Ground Lease, the
Existing Liens, Existing Notes and those exceptions to title to the Real
Property that are satisfactory to Grande B as determined pursuant to Section
2.4(d) hereof.

                                       6
<PAGE>

               "Personal Property" shall mean collectively the Tangible Personal
Property and the Intangible Personal Property.

               "Prentiss' Organizational Documents" shall mean the
organizational documents and all amendments thereto of Prentiss.

               "Property" shall mean collectively the Real Property and the
Personal Property.

               "Real Property" shall mean the Land and the Improvements.

               "Rent Roll" shall have the meaning ascribed to such term in
Section 2.4(b)(2) of this Agreement.

               "Second Exchange Agreement" shall have the meaning ascribed to
such term in Recital B above.

               "Study Period" shall mean the period commencing on the date this
Agreement has been fully executed and delivered by all parties hereto, and
continuing through February 16, 2001. Except as expressly noted herein to the
contrary, time periods herein referred to shall mean the time periods as in
effect, from time to time, at Dallas, Texas.

               "Submission Matters" shall mean all items Prentiss is required to
deliver to Prentiss pursuant to Section 2.4(b) hereof.

               "Survey" shall mean the survey defined as such in and prepared
pursuant to Section 2.4(d) hereof.

               "Tangible Personal Property" shall mean the items of tangible
personal property consisting of all furniture, fixtures, equipment, machinery
and other personal property of every kind and nature located on or used or
useful in the ownership and operation of the Property and owned by Prentiss,
including, without limitation, Prentiss' interest as lessee with respect to any
such Tangible Personal Property, other than (a) the items of personal property
identified on Exhibit D hereto, and (b) the Leased Property, the title to which
personal property described in clauses (a) and (b) is not being transferred
pursuant to this Agreement.

               "Title Commitment" shall mean the title commitment and exception
documents defined as such in Section 2.4(d) hereof.

               "Title Company" shall mean Fidelity National Title Insurance
Company or other title insurance underwriter selected by Grande B.

               "UCC Reports" shall mean the reports defined as such in Section
2.4(d) hereof.

               "Utilities" shall mean public sanitary and storm sewers, natural
gas (if any), telephone, public water facilities, electrical facilities and all
other utility facilities and services (if any) necessary or appropriate for the
operation and occupancy of the Property as an office building.

                                       7
<PAGE>

               "Warranties and Guaranties" shall mean all warranties and
guaranties relating to the Improvements, or the Tangible Personal Property or
any part thereof.

                                  ARTICLE II.
          EXCHANGE OF PROPERTY; DEPOSIT; EXCHANGE VALUE; STUDY PERIOD;
                 CONVEYANCE SUBJECT TO EXISTING NOTES AND LIENS

         2.1   Exchange Property. On the Closing Date, Prentiss agrees to
transfer the Property to Grande B in accordance with and subject to the other
terms and conditions set forth herein, in exchange for the transfer of the
Exchange Property by Grande B to Prentiss in accordance with and subject to the
terms and conditions of the Second Exchange Agreement.

         2.2   Exchange Value; Conveyance Subject to Existing Notes and Liens.

               (a) Grande B and Prentiss hereby agree that the Exchange Value of
the Property is $107,200,000.00, to be allocated among the Parcels in a manner
to be agreed upon by Prentiss and Grande B on or before the Closing Date.

               (b) Grande B shall accept the Property subject to, but in no way
assuming, the unpaid balances of the Existing Notes payable to the lienholders
described in Exhibit E hereto having approximate unpaid principal balances in
the amounts specified in Exhibit E, and subject to, but in no way assuming the
obligations contained in the Existing Liens. Notwithstanding the foregoing, (i)
to the extent that any of the Existing Notes or Existing Liens (or the loan
documents executed in connection therewith) create personal liability for
specified acts, omissions or occurrences (such acts, omissions or occurrences
being referred to as "Carve-Out Activities") and the associated personal
liability being referred to as "Carve-Out Liability"), (A) Grande B shall, if
Closing occurs, be responsible for any such Carve-Out Liability attributable to
Carve-Out Activities accruing and occurring from and after the Closing Date, and
shall and does hereby indemnify and hold Prentiss harmless with respect thereto,
and (B) Prentiss shall and does hereby indemnify and hold Grande B harmless with
respect to Carve-Out Liability attributable to Carve-Out Activities accruing or
occurring prior to the Closing Date. If permitted by any holder of an Existing
Note, Prentiss shall be released from all Carve-Out Liability under such
Existing Note and Existing Liens securing payment of such existing Note, and
Grande B shall execute such documents as the holder of any such Existing Note
may reasonably require to evidence the assumption by Grande B of the Carve-Out
Liability attributable to Carve-Out Activities of Grande B accruing and
occurring from and after the Closing Date. The provisions of this Section 2.2(b)
shall survive the Closing.

         2.3   Deposit. Within three (3) days after the execution hereof by both
Prentiss and Grande B and as a condition precedent to the effectiveness of this
Agreement, Grande B shall deliver to Escrow Agent a wire transfer or check (a)
in the sum of Fifty Dollars ($50.00) (the "Independent Consideration"), payable
to the order of Prentiss representing the Independent Consideration for
Prentiss' execution of this Agreement and agreement to provide Grande B with the
Study Period (which check or the proceeds of which wire transfer shall
thereafter be delivered by Escrow Agent to Prentiss), and (b) in the sum of
$700,000.00 (the proceeds of which wire transfer or check Escrow Agent shall
deposit and invest in an interest bearing account at a financial institution
acceptable to Grande B or as otherwise agreed to in writing by Prentiss and

                                       8
<PAGE>

Grande B). The proceeds of the wire transfer or check are referred to herein as
the "Deposit" and Escrow Agent shall hold and invest the Deposit pursuant to the
terms, conditions and provisions of this Agreement. All accrued interest on the
Deposit shall become part of the Deposit. The Deposit (regardless of whether it
is the proceeds of a wire transfer or check) shall be either (a) returned to
Grande B pursuant hereto, or (b) paid to Prentiss pursuant hereto. For purposes
of reporting earned interest with respect to the Deposit, Prentiss's Federal Tax
Identification Number is 75-2672997, and Grande B's Federal Tax Identification
Number is 23-2977952.

         2.4   Study Period.

               (a) Grande B and its agents, contractors and duly authorized
representatives shall have the right, until 5:00 p.m., Dallas, Texas time on the
last day of the Study Period, and thereafter unless, as provided below, Grande B
notifies Prentiss in writing prior to the expiration of the Study Period that
Grande B has elected to terminate this Agreement, to enter upon the Real
Property and to perform, at Grande B's expense, such economic, surveying,
engineering, topographic, environmental, marketing and other tests, studies and
investigations as Grande B may deem appropriate. If such tests, studies and
investigations do not warrant, in Grande B's sole, absolute and unreviewable
discretion, the acquisition of the Property for the purposes contemplated by
Grande B, then Grande B may elect not to proceed with this transaction and shall
notify Prentiss and Escrow Agent, in writing prior to the expiration of the
Study Period, that Grande B has elected to terminate this Agreement, in which
event this Agreement automatically shall terminate, the Deposit shall be
promptly returned to Grande B and Grande B and Prentiss shall be released from
all further liability or obligation hereunder except those which expressly
survive a termination of this Agreement. If Grande B does not so notify Prentiss
of its determination to terminate this Agreement prior to the expiration of the
Study Period, then Grande B shall be deemed to have waived its right to
terminate this Agreement pursuant to this Section 2.4.

               (b) Prentiss has delivered or made available at the Property the
following to Grande B:

                   (1) Copies of all Leases in effect as of the date of this
         Agreement, together with, to the extent in Prentiss' possession or
         reasonably available to Prentiss, copies of all correspondence received
         from or sent to tenants of the Property.

                   (2) a Rent Roll (herein so called) certificate (with current
         rent roll and accounts receivable report attached) for the Property
         containing the following information with respect to each Lease: (i) a
         description of the space occupied thereby (including square feet, type
         of space, floor and tenant's pro rata share of common elements), (ii)
         tenant's name, (iii) the commencement date and expiration date thereof,
         (iv) the rental rate per square foot, (v) the amount of fixed monthly
         rental, (vi) the amount of any percentage or other additional rental
         and/or common area maintenance, tax, insurance and operating expenses
         and any other charges payable thereunder and, if applicable, the base
         year used in each Lease, (vii) the amount of any prepayment in rental,
         (viii) the amount of the security deposit or any other deposit
         thereunder, (ix) any free rent, concessions, rebates, refunds,
         refurbishment allowances or other inducements which any tenant will be

                                       9
<PAGE>

         entitled to receive after December 31, 2000 (including, without
         limitation, any of the foregoing that may be payable in connection with
         renewals, extensions or expansions expressly contemplated in any of
         such Leases), (x) any options provided thereunder, including, without
         limitation, any renewal options, expansion options, purchase options
         and rights of first refusal and (xi) delinquency in rental or other
         charges set forth in the attached accounts receivable report.

                   (3) To the extent in Prentiss' possession or reasonably
         available to Prentiss, copies of all Authorizations including, without
         limitation, all certificates of occupancy, permits, authorizations,
         approvals (including drawings and enacting ordinances, if any), special
         exceptions, variances, and licenses issued by Governmental Authorities
         having jurisdiction over the Property and copies of all certificates
         issued by the local board of fire underwriters (or other body
         exercising similar functions) relating to the Property. For the purpose
         of this Agreement any Submission Matters in the possession of Prentiss
         or Prentiss' management company shall be deemed to be "reasonably
         available to Prentiss."

                   (4) To the extent in Prentiss' possession or reasonably
         available to Prentiss: (X) operating statements showing all income and
         expenses, profits and losses of the Property for the previous three (3)
         calendar years, which shall reflect (i) ad valorem taxes for the City,
         County and State or Commonwealth; (ii) expenses incurred for such
         period for water, electricity, natural gas and other utility charges;
         (iii) other operating expenses; (iv) total rents collected from tenants
         for such periods; and (v) other revenue collected and nature of such
         revenue; and (Y) financial statements for the Property for the previous
         three (3) calendar years, including, if available, the reports of
         accountants thereon.

                   (5) Operating and capital expenditure budgets for the current
         calendar year and, to the extent in Prentiss' possession or reasonably
         available to Prentiss, for the previous three (3) calendar years.

                   (6) All existing surveys and title policies for the Property
         that are reasonably available to Prentiss.

                   (7) A complete list of all Operating Agreements and leasing
         commission agreements in effect as of the date of this Agreement and
         complete copies of all such Operating Agreements and leasing commission
         agreements.

                   (8) A complete list of all Tangible Personal Property.

                   (9) To the extent in Prentiss' possession or reasonably
         available to Prentiss, any information in Prentiss' possession or
         reasonably available to Prentiss regarding current renditions or
         assessments on the Property or notices relative to change in valuation
         for ad valorem taxes.

                   (10) A complete list of all Warranties and Guaranties in
         effect as of the date of this Agreement and complete copies of all such
         Warranties and Guaranties.

                                       10
<PAGE>

                   (11) Copies of all soil tests, structural engineering tests,
         inspection reports, asbestos surveys, masonry tests, percolation tests,
         water, oil, gas, mineral, radon, formaldehyde, PCB or other
         environmental tests, audits or reports, market studies and site plans
         related to the Property in Prentiss' possession or reasonably available
         to Prentiss, together with copies of any and all correspondence,
         reports and other written documentation regarding the environmental
         aspects of the property or any toxic substances or equipment affecting
         or related to the Property.

                   (12) If in Prentiss' possession or reasonably available to
         Prentiss, copies of complete sets of all architectural, mechanical,
         structural and/or electrical plans and specifications used in
         connection with the construction of or alterations or repairs to the
         Property.

                   (13) If in Prentiss' possession or reasonably available to
         Prentiss, copies of as-built plans and specifications for the Property.

                   (14) Parking, structural, mechanical or other engineering
         reports or studies related to the Property, if any, in Prentiss'
         possession or reasonably available to Prentiss.

                   (15) To the extent in the possession of Prentiss or any
         affiliate of Prentiss or Prentiss' property manager, copies of credit
         reports and financial information on all tenants in possession of any
         of the Property and of any guarantors of such tenants' obligations.

                   (16) Copies of all approvals from any owners associations
         having jurisdiction over the Real Property and copies of all
         correspondence from any such owners association.

                   (17) Copies of the Existing Notes, Existing Liens and copies
         of any uncured notices of default or event of default from the
         holder(s) of the Existing Notes.

                   (18) A copy of each Ground Lease, and all amendments thereto.

                   (19) Copies of all Insurance Policies in effect, together
         with the name and telephone number of either a contact person at each
         insurance company or the insurance broker involved with the issuance of
         the Insurance Policies.

Grande B, copies of all materials, correspondence, books, records, financial
statements, operating statements and any and all other materials or information
relating to the Property which come into Prentiss' possession or control or are
otherwise reasonably available to Prentiss from and after the date on which the
Submission Matters were delivered to Grande B.

         Notwithstanding anything herein to the contrary, although Grande B has
not received all of the deliveries described in this Section 2.4(b), Grande B
has completed its feasibility study pursuant to Section 2.4(a) but reserves the
right to require, and Prentiss hereby agrees to deliver, to the extent available
to it, any item described in Section 2.4(b) not previously delivered at any time

                                       11
<PAGE>

during the period expiring six (6) months after the Closing Date, which
agreement shall survive the Closing Date for such six (6) month period.

               (c) Grande B shall indemnify and defend Prentiss against any
loss, damage or claim for personal injury or property damage (including
reasonable attorney's fees) arising from the entry upon the Property pursuant to
this Section 2.4 by Grande B or any agents, contractors or employees of Grande
B. Grande B, at its own expense, shall restore any damage to the Property caused
by any of the tests or studies made by Grande B. This provision shall survive
any termination of this Agreement and a closing of the transaction contemplated
hereby.

               (d) On or before 5:00 p.m. Dallas, Texas time on the date that is
five (5) days after the date of this Agreement, Prentiss shall deliver to Grande
B, at Prentiss' sole cost and expense, the most recent Surveys of the Land and
the Improvements for all of the Land and Improvements which constitute the
Property, which are in the possession of Prentiss. Such Surveys shall have been
prepared by a Surveyor(s) licensed to practice in the State where the Property
is located. During the Study Period, Grande B shall have the right to update
such Surveys, at Grande B's sole cost. On or before the Closing Date, Grande B
shall cause the Title Company to furnish to Grande B, at Prentiss' sole cost and
expense, (i) a title insurance commitment bearing an effective date subsequent
to the date of this Agreement issued by the Title Company covering the Real
Property, binding the Title Company to issue a ALTA Form Owner's Policy of Title
Insurance, showing title (which shall be leasehold title in the case of the
Leasehold Estate Land) to be held currently by Prentiss in a good, indefeasible
and insurable condition, together with legible copies of all documents
identified in such title insurance commitment as exceptions to title certified
as true and complete by the Title Company (collectively, the "Title
Commitment"), and (ii) reports of searches of the Uniform Commercial Code
records of both the county and State in which the Property is located
(collectively, the "UCC Reports") with respect to the state of title to the
Property. Prior to the expiration of the Study Period, Grande B shall notify
Prentiss of any matters shown on the Survey or identified in the Title
Commitment or the UCC Reports that Grande B is unwilling to accept
(collectively, "Grande B's Objections"); however, Grande B may not object to any
Ground Lease, the Existing Notes and Existing Liens. If any of Grande B's
Objections consist of delinquent taxes, mortgages, deeds of trust, security
agreements, construction or mechanics' liens, tax liens or other liens or
charges in a fixed sum or capable of computation as a fixed sum, then, to that
extent, notwithstanding anything herein to the contrary, Prentiss shall be
obligated to pay and discharge (or bond against in a manner sufficient to cause
the Title Company to insure over such Grande B's Objections) any such Grande B's
Objections and Escrow Agent is authorized to pay and discharge at Closing such
Grande B's Objections to the extent not paid and discharged or bonded against at
Closing. Prentiss shall not be obligated to incur any expenses to cure any
non-monetary Grande B's Objections (including, without limitation, any lis
pendens filed against the Property) unless Prentiss agrees to cure such
non-monetary Grande B's Objections as hereinafter provided. Prentiss shall
notify Grande B on or before the Closing Date whether Prentiss agrees to cure
such non-monetary Grande B's Objections. If Prentiss notifies Grande B in
writing on or before the Closing Date that Prentiss agrees to cure such
non-monetary Grande B's Objections, Prentiss shall correct such non-monetary
Grande B's Objections on or before the Closing Date to the reasonable
satisfaction of Grande B. If Prentiss does not notify Grande B on or before the
Closing Date of its agreement to cure such non-monetary Grande B's Objections,
Prentiss shall be deemed to have elected not to cure such non-monetary Grande
B's Objections, and Grande B shall elect (1) to waive such non-monetary Grande

                                       12
<PAGE>

B's Objections or (2) to terminate this Agreement, in which case the Deposit
shall be promptly returned to Grande B and the parties hereto shall be released
from all further obligations hereunder except those which expressly survive a
termination of this Agreement. Prentiss shall not, after the date of this
Agreement, subject the Real Property to or permit or suffer to exist any liens,
encumbrances, covenants, conditions, restrictions, easements or other title
matters or seek any zoning changes or take any other action which may affect or
modify the status of title without Grande B's prior written consent. The
Existing Notes, Existing Liens, each Ground Lease and all title matters revealed
by the Title Commitment, UCC Reports and Survey and not objected to by Grande B
as provided above (other than those rendering title defeasible and delinquent
taxes, mortgages, deeds of trust, security agreements and other liens and
charges that are to be paid at Closing or bonded against as provided above)
shall be deemed Permitted Title Exceptions. Notwithstanding the foregoing,
Grande B shall not be required to take title to the Real Property subject to any
matters which (i) may arise subsequent to the effective date of the Title
Commitment, UCC Reports and Survey examined by Grande B during the Study Period,
and (ii) impairs title to any portion of the Property and will not be released
or bonded against on or before the Closing Date. If a title exception is
disclosed by the Title Company which was not shown in the Title Commitment or
Survey and was not the result of Prentiss' acts or omissions, then, unless
Prentiss notifies Grande B in writing by the Closing Date that Prentiss agrees
to take such action as may be necessary to release such title exception on or
before the Closing Date, Grande B may (i) terminate this Agreement by written
notice to Prentiss, in which event the Deposit shall be promptly returned to
Grande B and the parties hereto shall be released from all further obligations
hereunder except those which expressly survive a termination of this Agreement,
or (ii) waive its objections to such title exception and consummate the
transactions contemplated herein.

                                  ARTICLE III.
                    PRENTISS' REPRESENTATIONS AND WARRANTIES

         To induce Grande B to enter into this Agreement and to acquire the
Property, Prentiss makes the following representations and warranties with
respect to the Property, upon each of which Prentiss acknowledges and agrees
that Grande B is entitled to rely and has relied:

         3.1   Organization and Power. Prentiss is a limited partnership duly
formed, validly existing and in good standing under the laws of the State of
Delaware, is duly qualified to transact business in the Commonwealth of
Pennsylvania and State of Delaware, and has all requisite powers and all
material governmental licenses, authorizations, consents and approvals to carry
on its business as now conducted and to enter into and perform its obligations
hereunder and under any document or instrument required to be executed and
delivered on behalf of Prentiss hereunder.

         3.2   Authorization, Execution and Disclosure. This Agreement has been
duly authorized by all necessary action on the part of Prentiss, has been duly
executed and delivered by Prentiss, constitutes the valid and binding agreement
of Prentiss and is enforceable in accordance with its terms, subject to the
effect of applicable bankruptcy, insolvency, reorganization, arrangement,
moratorium or other similar laws affecting the rights of creditors generally.
Except for the consents of the holders of the Existing Notes, there is no other

                                       13
<PAGE>

person or entity who has an ownership interest in the Property or whose consent
is required in connection with Prentiss' performance of its obligations
hereunder which has not been obtained. The person executing this Agreement on
behalf of Prentiss has the authority to do so. Prentiss has not and will not
intentionally conceal any information regarding the Property.

         3.3   Non-contravention. The execution and delivery of, and the
performance by Prentiss of its obligations under, this Agreement do not and will
not (a) contravene, or constitute a default under, any provision of (i)
Prentiss' Organizational Documents, (ii) applicable law or regulation or any
agreement, judgment, injunction, order, decree or other instrument binding upon
Prentiss or to which the Property is subject, the result of which could have a
material adverse effect on the value of the Property or Prentiss' ability to
convey the Property to Grande B and/or Prentiss' ability to perform its
obligations under this Agreement, or (iii) result in the creation of any lien or
other encumbrance on any asset of Prentiss. There are no outstanding agreements
(written or oral) pursuant to which Prentiss (or any predecessor to or
representative of Prentiss) has agreed to sell or has granted an option or right
of first refusal to purchase the Property or any part thereof, except for that
certain purchase option held by Unisource, Inc. in connection with its Lease at
the building known as Southpoint V.

         3.4   No Special Taxes. Prentiss has no knowledge of, nor has it
received any notice of, any special taxes or assessments relating to the
Property or any part thereof or any planned public improvements that may result
in a special tax or assessment against the Property.

         3.5   Compliance with Existing Laws and Restrictive Covenants. To
Prentiss' knowledge, Prentiss possesses all Authorizations, each of which is
valid and in full force and effect, and no provision, condition or limitation of
any of the Authorizations has been breached or violated. Prentiss has received
no notice within the past three years, of any existing or threatened violation
of any provision of any (a) Applicable Laws including, but not limited to, those
of environmental agencies or insurance boards of underwriters with respect to
the ownership, operation, use, maintenance or condition of the Property or any
part thereof, or requiring any repairs or alterations to the Property other than
those that have been made prior to the date hereof, and (b) restrictive
covenants or deed restrictions affecting the Real Property, except as disclosed
in Section 3.15.

         3.6   Personal Property. Except for the Existing Liens, all of the
Personal Property being conveyed by Prentiss hereunder is free and clear of all
liens and encumbrances except for those which will be discharged by Prentiss at
Closing, and Prentiss has good and merchantable title thereto and the right to
convey same in accordance with the terms of this Agreement.

         3.7   Operating Agreements. There are no management, service, supply,
maintenance, employment or other contracts in effect with respect to the
Property of any nature whatsoever, written or oral, other than the Assumed
Operating Agreements and the Operating Agreements to be terminated pursuant to
the last sentence of this Section 3.7. To Prentiss' knowledge, Prentiss has
performed all of its obligations under each of the Assumed Operating Agreements
in all material respects and no fact or circumstance has occurred which, by
itself or with the passage of time or the giving of notice or both, would
constitute a default under any of the Assumed Operating Agreements. To Prentiss'
knowledge, all other parties to the Assumed Operating Agreements have performed
all of their obligations thereunder in all material respects, and are not in

                                       14
<PAGE>

default thereunder in any material respect. Prentiss has received no notice of
any intention by any of the parties to any of the Assumed Operating Agreements
to cancel the same, nor has Prentiss canceled any of same. At the written
request of Grande B, Prentiss shall cause any Operating Agreements which are
terminable without penalty to be terminated as of the Closing Date.

         3.8   Condemnation Proceedings; Roadways. Prentiss has received no
notice of any condemnation or eminent domain proceeding pending or, to Prentiss'
knowledge, no such action is threatened, against the Property or any part
thereof. Prentiss has no knowledge of any change or proposed change in the
route, grade or width of, or otherwise affecting, any street, creek or road
adjacent to or serving the Real Property.

         3.9   Actions or Proceedings. There is no action, suit or proceeding
pending or known to Prentiss to be threatened against or affecting Prentiss in
any court, before any arbitrator or before or by any Governmental Authority
which (a) in any manner raises any question affecting the validity or
enforceability of this Agreement or any other agreement or instrument to which
Prentiss is a party or by which it is bound and that is or is to be used in
connection with, or is contemplated by, this Agreement, (b) is reasonably likely
to materially and adversely affect the business, financial position or results
of operations of Prentiss or the Property, (c) is reasonably likely to
materially and adversely affect the ability of Prentiss to perform its
obligations hereunder, or under any document to be delivered pursuant hereto,
(d) is reasonably likely to create a lien on the Property, any part thereof or
any interest therein or (e) is reasonably likely to otherwise materially and
adversely affect the Property, any part thereof or any interest therein or the
use, operation, condition or occupancy thereof.

         3.10  Bankruptcy. No Act of Bankruptcy has occurred with respect to
Prentiss.

         3.11  Hazardous Substances. To Prentiss' knowledge, neither Prentiss
nor any previous owner, tenant, occupant or user of the Property, nor any other
person, has engaged in or permitted any operations or activities upon, or any
use or occupancy of the Property or any portion thereof, for the purpose of or
in any way involving the handling, manufacture, treatment, storage, use,
generation, release, discharge, refining, dumping or disposal of any Hazardous
Materials on, under, in or about the Property in violation of any Applicable
Laws. To Prentiss' knowledge, no Hazardous Materials have migrated from or to
the Property upon, about, or beneath other properties in violation of any
Environmental Requirements. To Prentiss' knowledge, neither the Property nor its
existing or prior uses fail or failed to materially comply with Environmental
Requirements. Prentiss has no knowledge of any permits, licenses or other
authorizations which are required under any Environmental Requirements with
regard to the current uses of the Property which have not been obtained and
complied with. To Prentiss' knowledge, neither Prentiss nor any prior owner,
occupant or user of the Property has received any written notice concerning any
alleged violation of Environmental Requirements in connection with the Property
or any liability for Environmental Damages in connection with the Property for
which Prentiss (or Grande B after Closing) may be liable. To Prentiss'
knowledge, no Hazardous Materials are constructed, deposited, stored or
otherwise located on, under, in or about the Property in violation of any
Environmental Requirements. To Prentiss' knowledge, there exists no writ,
injunction, decree, order or judgment outstanding, nor any lawsuit, claim,
proceeding, citation, summons or investigation, pending or threatened, relating
to any alleged violation of Environmental Requirements on the Property, or from

                                       15
<PAGE>

the suspected presence of Hazardous Materials thereon, or relating to any
Environmental Damages. To Prentiss' knowledge, there are no underground or above
ground chemical treatment or storage tanks, or gas or oil wells are located on
the Property. The representations and warranties made by Prentiss in this
Section 3.11 shall be subject to the matters disclosed in the environmental
reports delivered by Prentiss to Grande B pursuant to Section 2.4(b)(12) hereof.

         3.12  Parties in Possession. There are no parties in possession of the
Property except for tenants under written leases, copies of which will be
delivered to Grande B pursuant to the terms hereof.

         3.13  Leases. There are no leases, concessions or occupancy agreements
in effect with respect to the Real Property other than the Leases listed on the
Rent Roll attached as Schedule 3.13; and Schedule 3.13 attached hereto is a
complete and correct list of all Leases in effect on the date of this Agreement.
Prentiss has not sent out any written notice of any default to any tenant under
any Lease which has not been cured, except as set forth on Schedule 3.13. To
Prentiss' knowledge, Prentiss has performed all obligations required of it under
all of the Leases and there remain no unfulfilled obligations of Prentiss under
the Leases, the nonperformance of which could entitle a tenant to damages under
such Lease or could cause Prentiss to be in default under such Lease. Except as
shown on Schedule 3.13, no tenant has given written notice to Prentiss of its
intention to institute litigation with respect to any Lease that has not been
dismissed, and Prentiss has not been served with a citation notifying Prentiss
of any litigation with respect to any Lease that has not been dismissed. None of
the Leases and none of the rents or other amounts payable thereunder have been
assigned, pledged or encumbered except for (a) any assignments, pledges or
encumbrances which will be fully released on or before the Closing Date, and (b)
the Existing Liens. The Rent Roll is true, correct and complete in all material
respects as of the date shown in the Rent Roll and, to Prentiss' knowledge,
there has been no material adverse change with respect to any of the items shown
on the Rent Roll during the period from the date thereof to the date of this
Agreement, except as shown thereon.

         3.14  Leased Property. To Prentiss' knowledge, all leases of the Leased
Property, if any, are in good standing and free from default.

         3.15  No Unpaid Charges. Subject to Section 7.8 hereof, there are no
unpaid charges, debts, liabilities, claims or obligations arising from the
construction, occupancy, ownership, use or operation of the Property which could
give rise to any mechanic's or materialmen's or other statutory lien against the
Property, or any part thereof, or for which Grande B will be responsible or
which will be due upon the initial occupancy of vacant space (such as a water or
sewer connection or tap-in fee), except for the disputed capital assessments at
the Oaklands Corporate Center.

         3.16  Condition of Improvements. Prentiss has not received any written
notice, from any third party alleging that (a) any of the Improvements (i) are
defective in design or construction, (ii) are not in operating condition and a
satisfactory state of repair, or (iii) have roof leaks, (b) any mechanical
systems are not in reasonable working order and repair, or (c) Prentiss has
failed to operate the Property in a commercially reasonable manner consistent
with a modern office building; provided, however, the foregoing representation

                                       16
<PAGE>

and warranty as to notices received shall not include any representation or
warranty as to notices concerning the aesthetic or other subjective quality of
the design of the Property or any system, element or component thereof and no
representation or warranty shall be deemed made as to any defect disclosed in
any property condition report obtained by Grande B in connection with the
Property.

         3.17  Access. Prentiss has no knowledge of any pending or threatened
governmental proceeding or any other fact or condition which would limit or
result in the termination of the Property's existing access to and from public
streets or roads.

         3.18  No Commitments. No commitments have been made to any Governmental
Authority, utility company, school board, church or other religious body, or any
homeowners' association or any other organization, group or individual, relating
to the Property which would impose an obligation upon Grande B to make any
contribution or dedication of money or land or to construct, install or maintain
any improvements of a public or private nature on or off the Property. Without
limiting the generality of the foregoing, Prentiss is not a party to any paving
agreements or undertakings, payback agreements, revenue bonds, utility debt
service expenses or other charges or expenses upon or relating to any of the
Property or applicable thereto.

         3.19  Prentiss Is Not a "Foreign Person". Prentiss is not a "foreign
person" within the meaning of Section 1445 of the Internal Revenue Code, as
amended (i.e., Prentiss is not a foreign corporation, foreign partnership,
foreign trust, foreign estate or foreign person as those terms are defined in
the Internal Revenue Code and regulations promulgated thereunder).

         3.20  Leasing Commissions. No brokerage or leasing commissions or other
fees or compensation are due or payable, or will become due and payable as a
result of agreements in place, to any person, firm, corporation or other entity
with respect to or on account of any of the Leases or any extension or renewals
thereof, except as set forth on Schedule 3.20 or 6.4(g) hereof.

         3.21  Other Agreements. There are no options, contracts or other
obligations outstanding for the sale, exchange or transfer of any of the
Property or any interest therein which would be superior to the rights of Grande
B under this Agreement or which would survive Closing.

         3.22  Existing Secured Indebtedness. There is no debt secured by liens
on the Real Property, or any portion thereof, which will not be released and
discharged as of the Closing, other than the Existing Notes and the Existing
Liens. Prentiss is not in default under the Existing Notes or the Existing
Liens; to Prentiss' knowledge, no event has occurred which, with the passage of
time or the giving of notice, or both, would constitute a default thereunder;
and Exhibit E is true, accurate and complete in all material respects.

         3.23  Employment on "At-Will" Basis. All persons and entities presently
employed in connection with the operation and maintenance of the Property are
employed on an "at will" basis, are dischargeable upon thirty (30) days' notice
and, unless otherwise directed by Grande B, shall be terminated by Prentiss as
of Closing. There are no labor disputes pending, nor to the best of Prentiss'
knowledge, contemplated pertaining to the operation or maintenance of the

                                       17
<PAGE>

Property, or any part thereof. Prentiss has no employment agreements, either
written or oral, with any person which would require Grande B to employ any
person after the date hereof or the Closing Date.

         3.24  Ground Lease. Each Ground Lease is valid and in full force and
effect. Prentiss is not in default under any Ground Lease; to Prentiss'
knowledge, no event has occurred which, with the passage of time or the giving
of notice, or both, would constitute a default under any Ground Lease; and
Exhibit G is a true, accurate and complete listing, in all material respects, of
each Ground Lease and all amendments thereto.

         3.25  LIMITATIONS ON REPRESENTATIONS AND WARRANTIES. GRANDE B HEREBY
AGREES AND ACKNOWLEDGES THAT, EXCEPT AS SET FORTH IN THIS ARTICLE III, OR AS
OTHERWISE EXPRESSLY STATED HEREIN OR IN THE DEED OR IN ANY DOCUMENTS EXECUTED IN
CONNECTION HEREWITH, NEITHER PRENTISS NOR ANY AGENT, ATTORNEY, EMPLOYEE OR
REPRESENTATIVE OF PRENTISS HAS MADE ANY REPRESENTATION WHATSOEVER REGARDING THE
SUBJECT MATTER OF THIS AGREEMENT, OR ANY PART HEREOF, INCLUDING (WITHOUT
LIMITING THE GENERALITY OF THE FOREGOING) REPRESENTATIONS OR WARRANTIES AS TO
THE PHYSICAL NATURE OR CONDITION OF THE PROPERTY OR THE CAPABILITIES THEREOF,
AND THAT GRANDE B, IN EXECUTING, DELIVERING AND/OR PERFORMING THIS AGREEMENT,
DOES NOT RELY UPON ANY STATEMENT AND/OR INFORMATION TO WHOMEVER MADE OR GIVEN,
DIRECTLY OR INDIRECTLY, ORALLY OR IN WRITING, BY ANY INDIVIDUAL, FIRM OR
CORPORATION EXCEPT THOSE EXPRESSLY CONTAINED HEREIN OR DELIVERED PURSUANT
THERETO OR IN ANY DOCUMENTS EXECUTED IN CONNECTION HEREWITH. EXCEPT AS OTHERWISE
PROVIDED HEREIN, GRANDE B AGREES TO TAKE THE PROPERTY "AS IS," AS OF THE DATE
HEREOF, REASONABLE WEAR AND TEAR EXCEPTED. IN ADDITION, EXCEPT AS SET FORTH
HEREIN, PRENTISS MAKES NO REPRESENTATIONS OR WARRANTIES REGARDING THE COMPLIANCE
WITH ANY ENVIRONMENTAL REQUIREMENTS, INCLUDING THE EXISTENCE IN OR ON THE
PROPERTY OF HAZARDOUS MATERIALS. THE PROVISIONS OF THIS PARAGRAPH SHALL SURVIVE
THE CLOSING OR ANY TERMINATION HEREOF.

Each of the representations and warranties contained in this Article III and its
various subparagraphs are intended for the benefit of Grande B and may be waived
in whole or in part. All rights and remedies arising in connection with the
untruth or inaccuracy of any such representations and warranties shall survive
the Closing of the transaction contemplated hereby as provided in Section 10.11
hereof, except to the extent that Prentiss gives Grande B written notice prior
to Closing of the untruth or inaccuracy of any representation or warranty,
Grande B otherwise obtains actual knowledge prior to Closing of the untruth or
inaccuracy of any representation or warranty, and Grande B nevertheless elects
to close this transaction. Grande B shall be deemed to have actual knowledge of
the untruth or inaccuracy of any representation or warranty only if (i) Grande B
receives written notice from Prentiss satisfying the foregoing requirements, or
(ii) Gerard H. Sweeney, George Hasenecz, Michael Diliberto, Suzanne Stumpf or
Brad A. Molotsky has actual knowledge of any such untruth or inaccuracy. Except
to the extent otherwise expressly provided in the immediately preceding
sentence, no investigation, audit, inspection, review or the like conducted by

                                       18
<PAGE>

or on behalf of Grande B shall be deemed to terminate the effect of any such
representations, warranties and covenants, it being understood that Grande B has
the right to rely thereon and that each such representation and warranty
constitutes a material inducement to Grande B to execute this Agreement and to
close the transaction contemplated hereby and to pay the Purchase Price to
Prentiss.

If any of Prentiss' representations and warranties made hereunder are found by
Grande B to be incorrect prior to Closing to the extent they affect the Property
or its operation in any material respect, Grande B shall inform Prentiss in
writing and Grande B's sole remedy, except as otherwise expressly provided in
clause (a)(ii) of the first sentence of Section 9.3 hereof or the last sentence
of Section 9.3 hereof, shall be termination of this Agreement on account thereof
and refund of the Deposit. If Grande B elects not to so terminate this
Agreement, any remedy of Grande B for breach of such warranties and
representations made prior to the Closing shall be deemed to be irrevocably
waived. Notwithstanding anything to the contrary contained in this Article, if
Prentiss breaches any representation or warranty made by Prentiss and if prior
to Closing Grande B notifies Prentiss that it elects to terminate this Agreement
on account of such breach, Prentiss may by written notice to Grande B given or
before the Closing Date agree to cure the breach (which breach must be cured on
or before the Closing Date), and Grande B shall thereupon be obligated to close
the transaction and accept such cure as Grande B's sole remedy for such breach.

The term "to Prentiss' knowledge" or similar phrase shall mean the knowledge of
Prentiss' chief executive officer, general counsel, chief financial officer,
Hank Gulbrandsen, Peter Hausmann and the current building engineer, property
manager and leasing agent (collectively, "Prentiss' Personnel with Knowledge")
for the Property and such inquiry shall include the direction by Prentiss to
such persons to review all files in their possession relating to the operation,
ownership, maintenance and management of the Property. Prentiss covenants that
if prior to Closing Prentiss obtains actual knowledge that any of the facts
represented and warranted by Prentiss under this Agreement are or become untrue
or inaccurate in any material respect, it will promptly inform Grande B in
writing of its discovery.

Prentiss' Personnel with Knowledge shall not have any personal liability under
this Agreement in their respective capacities as officers and/or directors of
Prentiss.

                                  ARTICLE IV.
                    GRANDE B'S REPRESENTATIONS AND WARRANTIES

         To induce Prentiss to enter into this Agreement and to convey the
Property, Grande B and Brandywine OP hereby, jointly and severally, make the
following representations and warranties, upon each of which Grande B and
Brandywine OP acknowledge and agree that Prentiss is entitled to rely and has
relied:

         4.1   Organization and Power. Grande B and Brandywine OP are limited
partnerships, duly formed, validly existing and in good standing under the laws
of the State of Delaware, and have all requisite partnership powers and all
material governmental licenses, authorizations, consents and approvals required
to carry on their respective businesses as now conducted and to enter into and
perform its obligations under this Agreement and any document or instrument

                                       19
<PAGE>

required to be executed and delivered on behalf of Grande B and Brandywine OP
hereunder. Grande B has the financial capability to acquire the Property
pursuant to this Agreement.

         4.2   Non-contravention. The execution and delivery of this Agreement
and the performance by Grande B and Brandywine OP of their respective
obligations hereunder do not and will not contravene, or constitute a default
under, any provisions of Grande B's Organizational Documents or applicable law
or regulation, or any agreement, judgment, injunction, order, decree or other
instrument binding upon Grande B or Brandywine OP.

         4.3   Litigation. There is no action, suit or proceeding, pending or
known to be threatened, against or affecting Grande B or Brandywine OP in any
court or before any arbitrator or before any Governmental Authority which (a) in
any manner raises any question affecting the validity or enforceability of this
Agreement or any other agreement or instrument to which Grande B or Brandywine
OP is a party or by which each is bound and that is to be used in connection
with, or is contemplated by, this Agreement, (b) could materially and adversely
affect the business, financial position or results of operations of Grande B or
Brandywine OP, or (c) could materially and adversely affect the ability of
Grande B or Brandywine OP to perform its respective obligations hereunder, or
under any document to be delivered pursuant hereto.

         4.4   Bankruptcy. No Act of Bankruptcy has occurred with respect to
Grande B or Brandywine OP.

         4.5   Authorization, Execution and Disclosure. This Agreement has been
duly authorized by all necessary action on the part of Grande B and Brandywine
OP, has been duly executed and delivered by Grande B and Brandywine OP,
constitutes the valid and binding agreement of Grande B and Brandywine OP and is
enforceable in accordance with its terms, subject to the effect of applicable
bankruptcy, insolvency, reorganization, arrangement, moratorium or other similar
laws affecting the rights of creditors generally.

                                   ARTICLE V.
                              CONDITIONS PRECEDENT

         5.1   As to Grande B's Obligations. Grande B's obligations hereunder
are subject to the satisfaction of the following conditions precedent:

               (a) Prentiss' Deliveries. Prentiss shall have delivered to or for
the benefit of Grande B, on or before the Closing Date, all of the documents and
other information required of Prentiss pursuant to Sections 7.2 and 7.4 hereof.

               (b) Representations, Warranties and Covenants; Obligations of
Prentiss; Certificate. All of Prentiss' representations and warranties made in
this Agreement shall be true and correct in all material respects as of the date
hereof and as of the date of Closing as if then made; Prentiss shall have
performed in all material respects all of its covenants and other obligations
under this Agreement; and Prentiss shall have executed and delivered to Grande B
at Closing a certificate to the foregoing effect.

               (c) Title Insurance. Good and indefeasible fee simple title to
the Fee Estate Land and good and indefeasible title to the Leasehold Estate Land
shall be insurable as such by the Title Company, subject only to Permitted Title

                                       20
<PAGE>

Exceptions as determined in accordance with Section 2.4 hereof and including,
without limitation, all applicable deletions of standard exceptions and
endorsements permitted under applicable state law which are customarily required
by institutional investors purchasing property comparable to the Property.

               (d) Simultaneous Closings. There shall occur, simultaneously with
Closing hereunder, closing under the Second Exchange Agreement.

               (e) Condition of Improvements. The Improvements and the Tangible
Personal Property (including but not limited to the mechanical systems,
plumbing, electrical, wiring, fixtures, heating, air conditioning and
ventilating equipment, elevators, boilers, equipment, roofs, structural members
and furnaces) shall be in the same condition at Closing as they are as of the
date hereof, reasonable wear and tear excepted. Prentiss shall not have removed
or caused or permitted to be removed any part or portion of the Real Property or
the Tangible Personal Property without Grande B's prior written consent unless
the same is replaced, prior to Closing, with a similar item of at least equal
suitability, quality and value, free and clear of any lien or security interest.

               (f) Utilities. All of the Utilities shall be installed in and
operating at the Property, and service shall be available for the removal of
garbage and other waste from the Property.

               (g) Due Diligence Materials. All rent rolls, lists, schedules and
other documents furnished by Prentiss to Grande B under this Agreement shall be
true and correct in all material respects, except for inaccuracies as to which
Grande B was given written notice by Prentiss or otherwise had actual knowledge
prior to the end of the Study Period.

               (h) No Additional Proceedings; Tenant Defaults. Except for
matters as to which Grande B was given written notice by Prentiss or otherwise
had actual knowledge prior to the end of the Study Period, on the Closing Date,
there shall be no (a) litigation pending or threatened, seeking (i) to enjoin
the consummation of the transactions contemplated hereunder, (ii) to recover
title to the Property, or any part thereof or any interest therein, (iii) to
increase substantially ad valorem taxes theretofore assessed against any of the
Property, (iv) to enjoin the violation of any law, rule, regulation, restrictive
covenant or zoning ordinance that may be applicable to the Property, or (v)
claiming defaults or other liability of Prentiss under Leases by tenants leasing
five percent (5%) or more of the rentable square feet of the Improvements, in
the aggregate or (b) monetary default in excess of thirty (30) days for which a
written notice of default has been given to a tenant and which constitutes an
event of default under, and as defined in, the applicable Lease, other material
default or any threatened or reasonably anticipated material default by tenants
leasing five percent (5%) or more of the rentable square feet of the
Improvements, in the aggregate.

               (i) Estoppel Letters. The estoppel letters to be delivered at
Closing pursuant to Section 7.2(g) hereof shall have been obtained and delivered
and shall reflect no facts at material variance with the facts disclosed on the
Rent Roll and records provided to Grande B during the Study Period.

                                       21
<PAGE>

               (j) Lender Estoppel Letters. The lender estoppel letters to be
delivered at Closing pursuant to Section 7.2(y) hereof shall have been obtained
and delivered and shall reflect no facts at material variance with the facts
represented and warranted by Prentiss to Grande B hereunder.

               (k) Ground Lessor Estoppel Letters. Estoppel letters from each
Ground Lessor pursuant to Section 7.2(z) hereof.

               (l) ISRA. Prentiss shall obtain and deliver a Non-Applicability
Determination ("Non-Applicability Determination") from the Industrial Site
Evaluation Element of the New Jersey Department of Environmental Protection
pursuant to the Environmental Clean-Up Responsibility Act, as amended by the
Industrial Site Recovery Act, N.J.S.A. 13:1K-6 et seq., the regulations
promulgated thereunder and any amending or successor legislation and regulations
in connection with the transfer of portions of the Property located in the State
of New Jersey by Prentiss to Grande B.

               (m) Other Estoppel Letters. Estoppel letters described in Section
7.2(w) hereof.

Each of the conditions contained in this Section 5.1 are intended for the
benefit of Grande B and may be waived in whole or in part, by Grande B, but only
by an instrument in writing signed by Grande B.

         5.2   As to Prentiss' Obligations. Prentiss' obligations hereunder are
subject to the satisfaction of the following conditions precedent:

               (a) Grande B's Deliveries. Grande B shall have delivered to or
for the benefit of Prentiss, on or before the Closing Date, all of the documents
and payments required of Grande B pursuant to Sections 7.3 and 7.4 hereof.

               (b) Representations, Warranties and Covenants; Obligations of
Grande B. All of Grande B's representations and warranties made in this
Agreement shall be true and correct in all material respects as of the date
hereof and as of the date of Closing as if then made and Grande B shall have
performed in all material respects all of its covenants and other obligations
under this Agreement.

               (c) Simultaneous Closings. There shall occur, simultaneously with
Closing hereunder, closing under the Second Exchange Agreement.

Each of the conditions contained in this Section are intended for the benefit of
Prentiss and may be waived in whole or in part, by Prentiss, but only by an
instrument in writing signed by Prentiss.

                                  ARTICLE VI.
                              COVENANTS OF PRENTISS

         To induce Grande B to enter into this Agreement and to acquire the
Property in exchange for the Exchange Property, Prentiss covenants and agrees to
the following:

                                       22
<PAGE>

         6.1   Operating Agreements. Prior to the Closing Date, Prentiss shall
not enter into any new management agreement, maintenance or repair contract,
supply contract, lease in which it is lessee or other agreements with respect to
the Property which cannot be terminated on or before the Closing Date, nor shall
Prentiss enter into any agreements modifying the Operating Agreements in any
material respect, unless (a) any such agreement or modification will not bind
Grande B or the Property after the date of Closing or (b) Prentiss has obtained
Grande B's prior written consent to such agreement or modification. Prentiss
agrees to cancel and terminate effective as of the Closing Date all property
management agreements affecting the Property or any portion thereof and the
Operating Agreements to be terminated pursuant to the last sentence of Section
3.7 hereof.

         6.2   Warranties and Guaranties. Prentiss shall not before or after
Closing release or modify any Warranties and Guaranties, if any, except with the
prior written consent of Grande B.

         6.3   Insurance. Prior to the Closing Date, Prentiss shall pay all
premiums on, and shall not cancel or voluntarily allow to expire, any of
Prentiss' Insurance Policies unless such policy is replaced, without any lapse
of coverage, by another policy or policies providing coverage at least as
extensive as the policy or policies being replaced. Prentiss hereby indemnifies
and holds Grande B harmless from and against all losses, costs, damages and
expenses resulting from actions involving bodily or personal injury or property
damage in or about any of the Property that occurred prior to the Closing Date,
regardless of when the claim was made, but only to the extent coverage under the
applicable Insurance Policy or Policies is not sufficient and paid, and this
indemnity shall survive the Closing Date.

         6.4   Operation of Property Prior to Closing. Prentiss represents,
warrants, covenants and agrees with Grande B that, between the date of this
Agreement and the date of Closing:

               (a) Subject to the restrictions contained herein, Prentiss shall
operate the Property in the same manner in which Prentiss operated the Property
prior to the execution of this Agreement, so as to keep the Property in good
condition, reasonable wear and tear excepted.

               (b) Prentiss shall maintain its books of account and records in
the usual, regular and ordinary manner, in accordance with sound accounting
principles applied on a basis consistent with the basis used in keeping its
books in prior years.

               (c) Prentiss shall maintain in full force and effect all
Insurance Policies.

               (d) Prentiss shall punctually perform and discharge all
obligations and undertakings of Prentiss under the Leases and shall not permit a
default by Prentiss to occur thereunder.

               (e) Prentiss shall use and operate the Property in compliance
with Applicable Laws and the requirements of any mortgage, ground lease, Lease,
Operating Agreement and Insurance Policy affecting the Property.

               (f) Prentiss shall cause to be paid prior to delinquency all ad
valorem and other taxes due and payable with respect to the Property or its
operation.

                                       23
<PAGE>

               (g) Without the express prior written consent of Grande B (which
consent shall not be unreasonably withheld and shall be deemed to have been
given if Grande B fails to respond to a written request from Prentiss for such
consent within two (2) business days following Grande B's receipt of any such
request), Prentiss shall not: (i) enter into new Leases of any kind or nature
affecting the Property; or (ii) grant a renewal or extension of any existing
Lease, or consent to any assignment, sublease or expansion of any existing lease
or portion thereof which, by the terms of any such Lease, requires Prentiss'
prior consent as a condition to any such renewal, extension, assignment,
sublease or expansion. Prentiss shall not, without the express written consent
of Grande B, in any manner change, modify, extend, renew or terminate any Lease
except as required by the terms thereof, or waive in any material respect any of
the tenant's obligations under any Lease; provided, Leases with Prentiss'
management company may be terminated on or before the Closing Date without the
prior consent of Grande B. Prentiss shall not apply all or any part of the
security or damage deposit of a tenant under any Lease to obligations of such
tenant, unless such tenant has vacated its portion of the Property as of the
Closing Date. Notwithstanding the foregoing, Grande B hereby approves the new
Leases which have been entered into by Prentiss and costs associated therewith,
as more particularly described in Schedule 6.4(g) hereto.

               (h) Prentiss shall cause all debts and liabilities for labor,
materials, services and equipment incurred in the construction, operation and
development of the Property, including leasehold improvements, to be promptly
paid.

               (i) Neither Prentiss nor Prentiss' managing agent shall (1) make
any agreements which shall be binding upon Grande B with respect to the
Property, or (2) reduce, or cause to be reduced any rents or any other revenues
over which Prentiss has operational control.

               (j) Prentiss shall promptly deliver to Grande B upon Grande B's
request such reports showing the revenue and expenses of the Property as
Prentiss customarily keeps or receives internally for its own use.

               (k) Except as required by the terms thereof or hereof, Prentiss
shall not in any manner change, modify, extend, renew or terminate any Operating
Agreement which would be binding on Grande B with respect to the Property
without the express written consent of Grande B.

               (l) Prentiss shall promptly advise Grande B of any litigation,
arbitration or administrative hearing concerning or affecting the Property of
which Prentiss obtains actual knowledge.

               (m) Prentiss shall keep all existing indebtedness, if any,
current, shall comply with the terms and provisions of all debt instruments, not
modify any such debt instruments and shall immediately send Grande B copies of
all correspondence received from the holder(s) of such debt.

               (n) Prentiss shall keep the Existing Notes current, shall comply
with the terms and provisions of the Existing Notes and the Existing Liens and
shall immediately send Grande B copies of all correspondence received from any

                                       24
<PAGE>

of the holders of the Existing Notes. Prentiss shall not modify any provisions
of the Existing Notes or the Existing Liens.

               (o) Prentiss shall maintain each Ground Lease in full force and
effect and shall not enter into any modification or amendment to any Ground
Lease without the prior written consent of Grande B.

         6.5   No Marketing. Prentiss shall not market the Property for sale or
enter into discussions or negotiations with potential purchasers of the Property
unless this Agreement has been terminated pursuant to its terms.

         6.6   Leased Property. Prentiss shall be solely responsible for all
obligations relating to the Leased Property, and Grande B shall have no
obligations with respect thereto. The provisions of this Section 6.6 shall
survive the Closing.

The foregoing covenants of Prentiss are for the benefit of Grande B or its
assignee of its rights under this Agreement.

                                  ARTICLE VII.
                                     CLOSING

         7.1   Closing. The Closing shall occur within five (5) days after the
conditions precedent set forth in Sections 5.1 and 5.2 have been satisfied. As
more particularly described below, at the Closing the parties hereto will meet
to (i) execute all of the documents required to be delivered in connection with
the transactions contemplated hereby (the "Closing Documents"), (ii) deliver the
same to Escrow Agent, and (iii) take all other action required to be taken in
respect of the transactions contemplated hereby. The Closing will occur at the
offices of the Escrow Agent. At the Closing, Grande B shall deliver all title
instruments transferring title to the Exchange Property in accordance with the
Second Exchange Agreement to Escrow Agent, the Title Company shall update the
title to the Property and, provided there has been no change in the status of
title as reflected in the Title Commitment and Survey which has not been waived
by Grande B pursuant to Section 2.4(d) hereof, and Escrow Agent shall record the
Deeds, release and date, where appropriate, the Closing Documents in accordance
with the joint instructions of Prentiss and Grande B and shall send, by wire
transfer, all sums, if any, owing to Prentiss or Grande B hereunder to Prentiss
or Grande B, as applicable. At Closing, the Escrow Agent shall additionally
send, by wire transfer, the Deposit, less the Independent Consideration, to
Grande B. As provided herein, the parties hereto will agree upon adjustments and
prorations to certain items which cannot be exactly determined at the Closing
and will make the appropriate adjustments with respect thereto. Possession of
the Property shall be delivered to Grande B on the Closing Date, subject only to
Permitted Title Exceptions and the rights of tenants under the Leases.
Notwithstanding anything herein to the contrary, if the Closing Date does not
occur by April 30, 2001, and the provisions of Section 9.3 or 9.5 are not
applicable, then either party may terminate this Agreement by notice to the
other party hereto, in which event neither party shall have any further
obligation to the other except for the indemnities and other provisions of this
Agreement which expressly survive a termination of this Agreement, and the
Deposit, less the Independent Consideration, shall be promptly refunded to
Grande B.

                                       25
<PAGE>

         7.2   Prentiss' Deliveries. At the Closing, Prentiss shall deliver to
Escrow Agent all of the following instruments, each of which shall have been
duly executed and, where applicable, acknowledged and/or sworn on behalf of
Prentiss and shall be dated as of the Closing Date:

               (a)  The certificate required by Section 5.1(b) hereof.

               (b)  The Deeds and Assignments of Ground Leases.

               (c)  The Bill of Sale - Personal Property.

               (d)  The Assignment and Assumption Agreement.

               (e)  The Assignment of Leases.

               (f)  An updated certified Rent Roll dated as of the date
preceding the Closing Date.

               (g)  Either (i) an estoppel letter in the form of Exhibit C
hereto dated not more than thirty (30) days prior to the Closing Date (a) from
each of the tenants under the Leases covering 7,500 square feet or more, and (b)
from tenants leasing, in the aggregate, at least seventy-five percent (75%) of
the remainder of the Improvements, or (ii) an estoppel letter executed by
Prentiss certifying to the matters specified in Exhibit C hereto for any tenant
which does not execute an estoppel letter. Any estoppel letter provided by
Prentiss for a Lease pursuant to clause (ii) above shall state that Prentiss
shall have no liability thereunder if Prentiss subsequently provides to Grande B
an estoppel letter in the form of Exhibit C from the tenant under such Lease.

               (h)  Such agreements, affidavits or other documents as may be
required by the Title Company to issue the Owner's Title Policy subject only to
the Permitted Title Exceptions and to eliminate such standard exceptions and to
issue the endorsements thereto which are customarily required by institutional
investors purchasing property comparable to the Property.

               (i)  An updated Title Commitment issued by the Title Company,
dated as of the date and time of Closing, subject only to the Permitted Title
Exceptions.

               (j)  The FIRPTA Certificate.

               (k)  All original Warranties and Guaranties in Prentiss'
possession or reasonably available to Prentiss.

               (l)  To the extent in Prentiss' possession or reasonably
available to Prentiss, a valid, final and unconditional certificate of occupancy
for the Real Property and Improvements, issued by the appropriate Governmental
Authority and, if required by Applicable Laws, transferred to Grande B.

               (m)  The originals of the Assumed Operating Agreements, duly
assigned to Grande B and with such assignment acknowledged and approved by the
other parties to such Assumed Operating Agreements to the extent required by
such Assumed Operating Agreements.

                                       26
<PAGE>

               (n)  An assignment of each of the leases of the Leased Property
to Grande B, together with (i) the written consent of the lessors of such leases
to such assignment, if required by such leases, and (ii) executed originals of
all such leases in Prentiss' possession or reasonably available to Prentiss.

               (o)  Executed originals of all Leases, leases of Leased Property,
permits and, to the extent in Prentiss' possession or control, Authorizations
transferred or assigned to Grande B at Closing as required hereunder and any
other documents or instruments affecting the Property or the ownership and
operation thereof.

               (p)  All current real estate and personal property tax bills in
Prentiss' possession or under its control.

               (q)  All books, records, operating reports, appraisal reports,
files and other materials in Prentiss' possession or control which are necessary
in Grande B's reasonable discretion to maintain continuity of operation of the
Property. Grande B covenants to permit Prentiss to photocopy any of the matters
described in this Subparagraph 7.2(q) for a period of three (3) years following
the Closing Date, which covenant of Grande B shall survive for such three (3)
year period.

               (r)  Written notice executed by Prentiss notifying all interested
parties, including, without limitation, all tenants under any Leases, that the
Property has been conveyed to Grande B effective as of the Closing Date and
directing that all payments, inquiries and the like be forwarded to Grande B at
the address to be provided by Grande B (or as otherwise directed by Grande B).

               (s)  A current UCC Report showing no financing statements by
Prentiss as Debtor covering the Property, except in favor of the holders of the
Existing Notes.

               (t)  All keys to all locks on the Property in the possession of
Prentiss, together with an accounting for such keys in the possession of others.

               (u)  Possession of the Property subject only to the Permitted
Title Exceptions.

               (v)  Certified copies of a incumbency certificate and resolutions
authorizing the execution by Prentiss of this Agreement and all documents to be
executed by Prentiss on the Closing Date.

               (w)  Estoppel letters from each owners association created
pursuant to restrictive covenants or deed restrictions affecting the Real
Property certifying that (i) the Real Property complies with such restrictive
covenants or deed restrictions, and (ii) no assessments are due and owing with
respect to the Real Property, and estoppel letters from adjoining property
owners who are parties to adjoining landowner agreements binding on any portion
of the Real Property; provided, Prentiss may execute an estoppel letter
certifying to the foregoing matters for an owners association or property owner
that does not execute any such estoppel letter, which estoppel letter shall
continue in effect unless and until the applicable estoppel letter is
subsequently provided from any such owners association or property owner.

                                       27
<PAGE>

               (x)  Any other document or instrument reasonably requested by
Grande B in connection with the transactions contemplated hereby.

               (y)  An estoppel certificate executed by the present holders of
each of the Existing Notes substantially in the form of Exhibit F attached
hereto. Any and all fees and charges in connection with obtaining such written
consent or approval (specifically including, but not limited to, loan transfer
fees) shall be at Prentiss' sole cost and expense.

               (z)  An estoppel certificate executed by each Ground Lessor in a
form reasonably satisfactory to Prentiss and Grande B.

               (aa) The Non-Applicability Determination described in Section
5.1(k) hereof.

         7.3   Grande B's Deliveries.

               (a)  At the Closing, Grande B shall deliver to Escrow Agent all
title instruments transferring title to the Exchange Property, as set forth on
Exhibit B hereof, in accordance with Section 2.1 hereof and as required by the
terms and conditions of the Second Exchange Agreement.

               (b)  At the Closing, Grande B shall deliver to Prentiss the
Assignment and Assumption Agreement, each Assignment of Ground Lease and the
Assignment of Leases, duly executed by Grande B.

               (c)  At the Closing, Grande B shall deliver to Prentiss any other
document or instrument reasonably requested by Prentiss in connection with the
transactions contemplated hereby.

         7.4   Mutual Deliveries. At the Closing, Grande B and Prentiss shall
mutually execute and deliver each to the other:

               (a)  A final closing statement reflecting the adjustments and
prorations required hereunder and the allocation of income and expenses required
hereby.

               (b)  Such other and further documents, papers and instruments as
may be reasonably required by the parties hereto in connection with the
transactions contemplated hereby or their respective counsel.

         7.5   Closing Costs. Except as is explicitly provided in this
Agreement, each party hereto shall pay its own legal fees and expenses. Prentiss
shall pay for the costs associated with the releases of any deeds of trust,
mortgages and other financing encumbering the Property that Prentiss is to cause
to be released pursuant to this Agreement and for any costs associated with any
corrective instruments. Prentiss shall pay all costs for title searches, tax
certificates and all premiums for the issuance of the Title Policy; all costs of
providing the matters described in Sections 2.4(b) and (d) to Grande B; and
one-half (1/2) of any escrow fees or similar charges of the Escrow Agent. Grande
B shall pay one-half (1/2) of any escrow fees or similar charges of the Escrow
Agent. Prentiss shall pay all prepayment penalties and other costs and expenses
payable in connection with debt which Prentiss is required to prepay on the
Closing Date, and Prentiss shall pay all debt transfer and similar fees

                                       28
<PAGE>

associated with the Existing Notes and the Existing Liens. Prentiss shall pay
all assessments levied or pending against the Property as of the Closing Date.
Transfer taxes and documentary transfer stamps shall be paid in accordance with
the local customs in the States in which the Property is located. All other
expenses incurred by Prentiss or Grande B with respect to the Closing shall be
borne and paid for exclusively by the party incurring same, without
reimbursement, except to the extent otherwise specifically provided herein.

         7.6   Revenue and Expense Allocations. All revenues (including
operating expense escalations) and expenses with respect to the Property, and
applicable to the period of time before and after Closing, determined in
accordance with sound accounting principles consistently applied, shall be
allocated between Prentiss and Grande B as provided herein. Prentiss shall be
entitled to all revenue and shall be responsible for all expenses for the period
of time up to but not including the Closing Date, and Grande B shall be entitled
to all revenue and shall be responsible for all expenses for the period of time
from, after and including the date of Closing. Such adjustments shall be shown
on the closing statements (with such supporting documentation as the parties
hereto may require being attached as exhibits to the closing statements) and
shall increase or decrease (as the case may be) the cash amount payable by the
parties hereto. Without limiting the generality of the foregoing, the following
items of revenue and expense shall be allocated at Closing:

               (a)  Current rents and rents payable under each Ground Lease.

               (b)  Real estate and personal property taxes for the Property for
the current calendar year 2001.

               (c)  Revenue and expenses under the Assumed Operating Agreements
to be assigned to and assumed by Grande B.

               (d)  Utility charges (including, but not limited to, charges for
water, sewer and electricity).

               (e)  Municipal or other governmental improvement liens, which
shall be paid by Prentiss at Closing where the work has physically commenced,
and which shall be assumed by Grande B at Closing where the work has been
authorized, but not physically commenced.

               (f)  All other revenues (including CAM charges) and expenses of
the Property.

               (g)  Interest on the Existing Notes.

Grande B shall receive a credit for purposes of calculating closing prorations
for the total of (i) prepaid rents and (ii) unforfeited security deposits
together with interest thereon held by Prentiss under Leases.

The amount of any escrow accounts held by the holder(s) of the Existing Notes
shall be transferred to Grande B by Prentiss and paid for by Grande B.

                                       29
<PAGE>

Prentiss shall pay or cause to be paid all real estate taxes and installments
for special assessments (prorated to the Closing Date) for the Property due and
payable in, or deferred with respect to the years prior to, the year in which
the Closing occurs. All installments for special assessments (prorated to the
Closing Date) pending, levied or due and payable on or prior to the Closing Date
shall be paid by Prentiss on or before the Closing Date. All subdivision and
platting costs and expenses heretofore incurred by Prentiss, including, without
limitation, all subdivision exactions, fees and costs and all dedication of land
for parks and other public uses or payment of fees in lieu thereof, shall be
paid by Prentiss on or prior to the Closing Date.

If accurate allocations cannot be made at Closing because current bills are not
obtainable (as, for example, in the case of utility bills and/or real estate or
personal property taxes), the parties shall allocate such revenue or expenses at
Closing on the best available information, subject to adjustment upon receipt of
the final bill or other evidence of the applicable revenue or expense. The
obligation to make the adjustment shall survive the closing of the transaction
contemplated by this Agreement. Any revenue received or expense incurred by
Prentiss or Grande B with respect to the Property after the Closing Date shall
be promptly allocated in the manner described herein and the parties shall
promptly pay or reimburse any amount due. Prentiss shall calculate and deliver
to Grande B for its approval and its transmittal to tenants under Leases,
reconciliations of operating costs for the calendar year 2000, and Grande B
shall inform the tenants that Prentiss prepared such reconciliations and can be
contacted to discuss any questions concerning such reconciliations. The
proration provisions of this Agreement shall survive the closing of the
transaction contemplated hereby for a period of eighteen (18) months.

         7.7   Delinquent Rents. Any rents or other amounts which are delinquent
as of the Closing shall not be adjusted or prorated at Closing, but Grande B
shall make a reasonable attempt to collect such amounts for the benefit of
Prentiss after the Closing; provided, however, that nothing contained herein
shall be construed to require Grande B to institute any lawsuit or other
proceedings to collect such delinquent amounts. In this connection, the first
monies collected by Grande B from tenants or other persons owing delinquent
rents or other amounts shall be applied to Grande B's costs of collection, then
to the current rents or obligations of such person to Grande B, and the balance,
if any, shall be delivered to Prentiss, to the extent of the delinquency.
Prentiss shall be permitted to bring collection suits against tenants owing rent
to Prentiss that is more than thirty (30) days in arrears; however, Prentiss may
not bring eviction actions against any tenants under any of the Leases.

         7.8   Costs Associated with Certain Leasing Activities. Except as
otherwise expressly set forth in this Section 7.8, all refurbishment allowances,
tenant improvement costs and leasing commissions owing or which could become due
and owing with respect to Leases entered into on or before the Closing Date
shall be paid by Prentiss when due, and Prentiss shall indemnify and hold
harmless Grande B for claims brought against the Property or Grande B arising
therefrom, which indemnity shall survive the Closing. Notwithstanding the
foregoing: (i) Grande B shall pay to Prentiss at the Closing an amount equal to
the cost of all (x) leasing commissions paid by Prentiss, prior to the Closing
Date, to brokers other than affiliates of Prentiss and (y) capital improvement
costs incurred and paid by Prentiss prior to the Closing Date in completing
tenant improvements pursuant to (in the case of both (x) and (y)) (a) Leases
entered into by Prentiss on or after January 1, 2001 and other Leases, which are
described on Schedule 6.4(g) or which have been approved or deemed approved by
Grande B pursuant to Section 6.4(g); (b) renewals, extensions or expansions of
existing Leases expressly requiring the approval of Prentiss as a condition to
the exercise of such options which are exercised on or after January 1, 2001,
which either are described on Schedule 6.4(g) or have been approved or deemed

                                       30
<PAGE>

approved by Grande B pursuant to Section 6.4(g); and (c) renewals, extensions or
expansions of existing Leases not requiring the approval of Prentiss as a
condition to the exercise of such options which have been exercised on or after
January 1, 2001; and (ii) Grande B shall be responsible for refurbishment
allowances, tenant improvement costs and leasing commissions shown in the Rent
Roll or contained in Leases delivered pursuant to Section 2.4(b)(1) hereof that
have not been previously paid by Prentiss but are payable following the Closing
Date under existing Leases on or after January 1, 2001 or which are contained in
Leases entered into between January 1, 2001 and the Closing Date which are
described on Schedule 6.4(g) or which have been approved or deemed approved
pursuant to Section 6.4(g) hereof. The provisions of this Section 7.8 shall
survive the Closing Date.

                                 ARTICLE VIII.
                               GENERAL PROVISIONS

         8.1   Condemnation. In the event of any actual or threatened taking,
pursuant to the power of eminent domain, of all or any portion of the Real
Property, or any proposed sale in lieu thereof, Prentiss shall give written
notice thereof to Grande B promptly after Prentiss learns or receives notice
thereof. If all or any part of the Real Property is, or is to be, so condemned
or sold, Grande B shall have the right to terminate this Agreement pursuant to
Section 9.3 hereof. If Grande B elects not to terminate this Agreement, all
proceeds, awards and other payments arising out of such condemnation or sale
(actual or threatened) shall be paid or assigned, as applicable, to Grande B at
Closing. Prentiss shall not settle or compromise any such proceeding without
Grande B's written consent. If Grande B elects to terminate this Agreement by
giving Prentiss written notice thereof prior to the Closing, the Deposit shall
be promptly returned to Grande B and all rights and obligations of Prentiss and
Grande B hereunder (except those set forth herein which expressly survive a
termination of this Agreement) shall terminate immediately.

         8.2   Risk of Loss. The risk of any loss or damage to the Property
prior to the recordation of the Deed shall remain upon Prentiss. If any such
loss or damage occurs prior to Closing which exceeds an amount equal to five
percent (5%) of the Exchange Value, Grande B shall have the right to terminate
this Agreement pursuant to Section 9.3 hereof. If Grande B elects not to
terminate this Agreement pursuant to the immediately preceding sentence or a
loss or damage occurs prior to Closing which does not exceed five percent (5%)
of the Exchange Value, all insurance proceeds and rights to proceeds arising out
of such loss or damage, less the reasonable expenses incurred in collecting such
proceeds and, to the extent payable from insurance proceeds, reasonable expenses
incurred in securing the Property following a casualty, shall be paid or
assigned, as applicable, to Grande B at Closing and Prentiss shall pay Grande B
at the Closing the amount of any deductibles under the policies of insurance
covering such loss or damage. Prentiss shall be entitled to retain rent loss
insurance proceeds received that are attributable to periods prior to the
Closing Date. If Grande B elects to terminate this Agreement pursuant to this
Section 8.2 by giving Prentiss written notice thereof prior to the Closing, the
Deposit shall be promptly returned to Grande B and all rights and obligations of

                                       31
<PAGE>

Prentiss and Grande B hereunder (except those set forth herein which expressly
survive a termination of this Agreement) shall terminate immediately.

         8.3   Broker. There is no real estate broker involved in this
transaction. Grande B warrants and represents to Prentiss that Grande B has not
dealt with any real estate broker in connection with this transaction, nor has
Grande B been introduced to the Property or to Prentiss by any real estate
broker, and Grande B shall indemnify Prentiss and hold Prentiss harmless from
and against any claims, suits, demands or liabilities of any kind or nature
whatsoever arising on account of the claim of any other person, firm or
corporation to a real estate brokerage commission or a finder's fee or a
financial advisory fee as a result of having dealt with Grande B, or as a result
of having introduced Grande B to Prentiss or to the Property. In like manner,
Prentiss warrants and represents to Grande B that Prentiss has not dealt with
any real estate broker in connection with this transaction, nor has Prentiss
been introduced to Grande B by any real estate broker, and Prentiss shall
indemnify Grande B and save and hold Grande B harmless from and against any
claims, suits, demands or liabilities of any kind or nature whatsoever arising
on account of the claim of any person, firm or corporation to a real estate
brokerage commission or a finder's fee or a financial advisory fee as a result
of having dealt with Prentiss in connection with this transaction. This
provision shall survive any termination of this Agreement and a closing of the
transaction contemplated hereby.

         8.4   Bulk Sale. It shall be the obligation of Prentiss to comply with
any bulk sale requirements, statutes, laws, ordinances and regulations
promulgated with respect thereto, if any, in the State in which the Property is
located, or in or by any governmental entity having jurisdiction with respect
thereto, and to provide proof of such compliance or proof that no such
compliance is required, to Grande B, at or prior to Closing. In any event,
Prentiss shall indemnify Grande B and save and hold Grande B harmless from and
against any claims, suits, demands, liabilities or obligations of any kind or
nature whatsoever, including all costs of defending same, and reasonable
attorneys' fees paid or incurred in connection therewith, arising out of or
relating to any claim made by any third party or any liability asserted by any
third party that any applicable bulk sales law or like statute has not been
complied with. The provisions of this Section shall survive the Closing of the
transaction contemplated hereby.

                                  ARTICLE IX.
               LIABILITY OF GRANDE B; INDEMNIFICATION BY PRENTISS;
                           DEFAULT; TERMINATION RIGHTS

         9.1   Liability of Grande B. Except for obligations expressly assumed
or agreed to be assumed by Grande B hereunder, Grande B is not assuming any
obligations of Prentiss or any liability for claims arising out of any act,
omission or occurrence which occurs, accrues or arises prior to the Closing
Date, and Prentiss hereby indemnifies and holds Grande B harmless from and
against any and all claims, costs, penalties, damages, losses, liabilities and
expenses (including reasonable attorneys' fees) that may at any time be incurred
by Grande B as a result of (a) obligations of Prentiss not expressly assumed or
agreed to be assumed by Grande B hereunder, or (b) acts, omissions or

                                       32
<PAGE>

occurrences which occur, accrue or arise prior to the Closing Date. Grande B
hereby indemnifies and holds Prentiss harmless from and against any and all
claims, costs, penalties, damages, losses, liabilities and expenses (including
reasonable attorneys' fees) that may at any time be incurred by Prentiss as a
result of acts, omissions or occurrences relating to the Property arising and
accruing from and after the Closing Date. The provisions of this Section shall
survive the Closing of the transaction contemplated hereby.

         9.2   Indemnification by Prentiss. Prentiss hereby indemnifies and
holds Grande B and Grande B's officers, partners, directors, shareholders,
agents and employees (collectively, the "Indemnified Parties") harmless from and
against any and all claims, costs, penalties, damages, losses, liabilities and
expenses (including reasonable attorneys' fees) that may at any time be incurred
by Grande B, whether incurred before or after Closing, as a result of any
inaccuracy or breach by Prentiss of any of its representations, warranties,
covenants or obligations set forth herein or in any other document delivered by
Prentiss pursuant hereto except for any breach or inaccuracy of any
representation or warranty as to which Prentiss has given Grande B written
notice prior to Closing of the untruth or inaccuracy or of which Grande B
otherwise had actual knowledge prior to the Closing and nevertheless elected to
consummate the Closing; provided, however, the foregoing knowledge limitation on
Prentiss' indemnity shall not limit Grande B's remedy described in Section
9.3(a)(ii) hereof or in the last sentence of Section 9.3 hereof. The provisions
of this Section shall survive the Closing of the transaction contemplated hereby
as provided in Section 10.11 hereof, and shall, following any assignment of this
Agreement by Grande B, continue in favor of the Indemnified Parties of the
original Grande B hereunder as well the Indemnified Parties of any assignee
during said survival period.

         9.3   Default by Prentiss/Failure of Conditions Precedent. If any
condition set forth herein for the benefit of Grande B cannot or will not be
satisfied prior to Closing, or upon the occurrence of any other event that would
entitle Grande B to terminate this Agreement and its obligations hereunder, and
if Prentiss fails to cure any such matter or satisfy that condition within ten
(10) business days after notice thereof from Grande B (or such other time period
as may be explicitly provided for herein), Grande B, at its option, may elect
(a) to terminate this Agreement, in which event (i) the Deposit, less the
Independent Consideration, shall be promptly returned to Grande B, (ii) if the
condition which has not been satisfied is a breach of a representation, warranty
or covenant known by Prentiss to have been inaccurate or misleading when made,
then Prentiss shall be obligated upon demand to reimburse Grande B for Grande
B's actual out-of-pocket inspection, financing and other costs related to Grande
B's entering into this Agreement, inspecting the Property and preparing for a
Closing of the transaction contemplated hereby, including, without limitation,
Grande B's attorneys' fees incurred in connection with the preparation,
negotiation and execution of this Agreement and in connection with Grande B's
due diligence review, audits and preparation for a Closing up to an aggregate
amount equal to $100,000.00; provided, the foregoing shall not limit or include
the sums which may be payable by Prentiss pursuant to Section 9.6 below, and
(iii) all other rights and obligations of Prentiss and Grande B hereunder
(except those set forth herein which expressly survive a termination of this
Agreement) shall terminate immediately; (b) elect to proceed to Closing; or (c)
seek to enforce Prentiss' obligations hereunder by specific performance. If
Grande B elects to proceed to Closing and there is either a misrepresentation or
breach of a warranty by Prentiss (other than a breach of a representation or
warranty of which Grande B had actual knowledge prior to the Closing and
nevertheless elected to consummate the Closing) or the breach of a covenant by
Prentiss or a failure by Prentiss to perform its obligations hereunder first
discovered by Grande B after the Closing Date, Grande B shall retain all
remedies accruing as a result thereof, including, but not limited to, the remedy
of specific performance of Prentiss' covenants and obligations and the remedy of
the recovery of all reasonable damages resulting from Prentiss' breach of
warranty or covenant. Notwithstanding the foregoing, if the condition which has

                                       33
<PAGE>

not been satisfied is a breach of one or more representations and warranties by
Prentiss and/or Prentiss Properties Limited, Inc. ("PPL") in this Agreement
and/or in any of the other documents executed of even date herewith among
Prentiss, PPL, Grande B, Brandywine OP or any of their respective affiliates
(the "Other Documents"), Grande B has elected to proceed to Closing, and Grande
B can reasonably quantify the damage resulting from such breach of
representations and warranties with reasonable support for such calculation of
damages, then (i) if the aggregate damage is no greater than $150,000.00 (the
"First Threshold Level"), then Prentiss shall have no obligation to either cure
such breaches of representations and warranties or pay Grande B at Closing in
the event Grande B elects to close the transaction described in this Agreement
and the Other Documents; (ii) if such aggregate damage is greater than the First
Threshold Level but less than $1,500,000.00, then Prentiss must prior to the
Closing Date either cure such breaches of representations and warranties to the
reasonable satisfaction of Grande B or Prentiss shall pay Grande B at the
Closing an amount equal to the actual damages as reasonably determined by Grande
B as aforesaid, less the First Threshold Level; and (iii) in the event the
aggregate damages resulting from such breaches of representations and warranties
would exceed $1,500,000.00, then Grande B may either (A) terminate this
Agreement and the Other Documents, in which event the Deposit (less the
Independent Consideration) shall be promptly refunded, or (B) Grande B may close
the transaction as described in this Agreement and the Other Documents and
Grande B shall be paid by Prentiss the amount of $1,350,000.00, which amount
shall be the maximum aggregate amount payable by Prentiss and/or PPL under the
last sentence of Section 9.3 of this Agreement and all of the Other Documents.

         9.4   Indemnification by Grande B. Grande B hereby indemnifies and
holds Prentiss harmless from and against any and all claims, costs, penalties,
damages, losses, liabilities and expenses (including reasonable attorneys' fees)
that may at any time be incurred by Prentiss, whether incurred before or after
Closing, as a result of any inaccuracy or breach by Grande B of any of its
representations, warranties, covenants or obligations set forth herein or in any
other document delivered by Grande B pursuant hereto except for any breach or
inaccuracy of any representation or warranty as to which Grande B has given
Prentiss written notice prior to Closing of the untruth or inaccuracy or of
which Prentiss otherwise had actual knowledge prior to the Closing and
nevertheless elected to consummate the Closing. The provisions of this Section
shall survive the Closing of the transaction contemplated hereby for the period
described in Section 10.11 hereof.

         9.5   Default by Grande B/Failure of Conditions Precedent. If any
condition set forth herein for the benefit of Prentiss (other than a default by
Grande B) cannot or will not be satisfied prior to Closing, and if Grande B
fails to satisfy that condition within ten (10) business days after notice
thereof from Prentiss (or such other time period as may be explicitly provided
for herein), Prentiss may, at its option, elect either (a) to terminate this
Agreement in which event the Deposit shall be promptly returned to Grande B and
the parties hereto shall be released from all further obligations hereunder
except those which expressly survive a termination of this Agreement, or (b) to
waive its right to terminate, and instead, to proceed to Closing. If, prior to
Closing, Grande B defaults in performing any of its obligations under this
Agreement (including its obligation to purchase the Property), and Grande B
fails to cure any such default within ten (10) business days after notice
thereof from Prentiss, then Prentiss' sole remedy for such default shall be
either (i) to terminate this Agreement and retain the Deposit or (ii) to pursue

                                       34
<PAGE>

the remedy of specific performance compelling Grande B to acquire the Property
pursuant to the provisions of this Agreement.

         9.6   Costs and Attorneys' Fees. In the event of any litigation or
dispute between the parties arising out of or in any way connected with this
Agreement, resulting in any litigation, then the prevailing party in such
litigation shall be entitled to recover its costs of prosecuting and/or
defending same, including, without limitation, reasonable attorneys' fees at
trial and all appellate levels. The provisions of this Section shall survive the
Closing of the transaction contemplated hereby.

         9.7   Limitation of Liability. Notwithstanding anything herein to the
contrary, except in the case of fraud by either party, the liability of each
party hereto resulting from the breach or default by either party shall be
limited to actual damages incurred by the injured party and except in the case
of fraud by either party, the parties hereto hereby waive their rights to
recover from the other party consequential, punitive, exemplary, and speculative
damages. The provisions of this Section 9.7 shall survive the Closing of the
transaction contemplated hereby.

                                   ARTICLE X.
                            MISCELLANEOUS PROVISIONS

         10.1  Completeness; Modification. This Agreement and the Second
Exchange Agreement constitute the entire agreement between the parties hereto
with respect to the transactions contemplated hereby and supersede all prior
discussions, understandings, agreements and negotiations between the parties
hereto. This Agreement may be modified only by a written instrument duly
executed by the parties hereto. Any waiver of rights under this Agreement shall
be effective only if in writing and duly executed and delivered by the party
against whom such waiver is asserted.

         10.2  Assignments. Grande B may assign its rights hereunder without the
consent of Prentiss to any affiliate of Grande B, in which event, except as
otherwise specified herein, such assignee shall be the "Grande B" hereunder;
however, any such assignment shall not relieve the original Grande B of its
obligations under this Agreement, including specifically the obligation to close
the purchase of the Property in accordance with this Agreement as though there
were no assignment.

         10.3  Successors and Assigns. This Agreement shall bind and inure to
the benefit of the parties hereto and their respective successors and assigns.

         10.4  Days. If any action is required to be performed, or if any
notice, consent or other communication is given, on a day that is a Saturday or
Sunday or a legal holiday in the jurisdiction in which the action is required to
be performed or in which is located the intended recipient of such notice,
consent or other communication, such performance shall be deemed to be required,
and such notice, consent or other communication shall be deemed to be given, on
the first business day following such Saturday, Sunday or legal holiday. Unless
otherwise specified herein, all references herein to a "day" or "days" shall
refer to calendar days and not business days.

                                       35
<PAGE>

         10.5  Governing Law. This Agreement and all documents referred to
herein shall be governed by and construed and interpreted in accordance with the
laws of the State of Delaware.

         10.6  Counterparts. To facilitate execution, this Agreement may be
executed in as many counterparts as may be required. It shall not be necessary
that the signature on behalf of both parties hereto appear on each counterpart
hereof. All counterparts hereof shall collectively constitute a single
agreement.

         10.7  Severability. If any term, covenant or condition of this
Agreement, or the application thereof to any person or circumstance, shall to
any extent be invalid or unenforceable, the remainder of this Agreement, or the
application of such term, covenant or condition to other persons or
circumstances, shall not be affected thereby, and each term, covenant or
condition of this Agreement shall be valid and enforceable to the fullest extent
permitted by law.

         10.8  Notices. All notices, requests, demands and other communications
hereunder shall be in writing and shall be delivered by hand, transmitted by
facsimile transmission, sent prepaid by Federal Express (or a comparable
overnight delivery service) or sent by the United States mail, certified,
postage prepaid, return receipt requested, at the addresses and with such copies
as designated below. Any notice, request, demand or other communication
delivered or sent in the manner aforesaid shall be deemed given or made (as the
case may be) when actually delivered to the intended recipient.

         If to Grande B:      Brandywine Realty Trust
                              14 Campus Boulevard, Suite 100
                              Newtown Square, PA  19073-3780
                              Attn: Brad A. Molotsky, General Counsel
                              Fax No.: 610-325-4628

         If to Prentiss:      Prentiss Properties Acquisition Partners, L.P.
                              3860 West Northwest Highway, Suite 400
                              Dallas, Texas  75220
                              Attn.: J. Kevan Dilbeck, General Counsel
                              Fax No.: (214) 350-2409

         With a copy to:      Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                              1700 Pacific Avenue, Suite 4100
                              Dallas, Texas  75201-4675
                              Attn.:  Randall M. Ratner, P.C.
                              Fax No.:  (214) 969-4343

         If to Escrow Agent:  Chicago Title Insurance Company
                              2001 Bryan Street, Suite 1700
                              Dallas, Texas  75201
                              Attn.: Ellen Schwab
                              Fax No.: (214) 965-1629

                                       36
<PAGE>

or to such other address as the intended recipient may have specified in a
notice to the other party. Any party hereto may change its address or designate
different or other persons or entities to receive copies by notifying the other
party and Escrow Agent in a manner described in this Section.

         10.9  Escrow Agent. Escrow Agent referred to in the definition thereof
contained in Section 1.1 hereof has agreed to act as such for the convenience of
the parties without fee or other charges for such services as Escrow Agent.
Escrow Agent shall not be liable: (a) to any of the parties for any act or
omission to act except for its own willful misconduct; (b) for any legal effect,
insufficiency, or undesirability of any instrument deposited with or delivered
by Escrow Agent or exchanged by the parties hereunder, whether or not Escrow
Agent prepared such instrument; (c) for any loss or impairment of funds that
have been deposited in escrow while those funds are in the course of collection,
or while those funds are on deposit in a financial institution, if such loss or
impairment results from the failure, insolvency or suspension of a financial
institution; (d) for the expiration of any time limit or other consequence of
delay, unless a properly executed written instruction, accepted by Escrow Agent,
has instructed Escrow Agent to comply with said time limit; or (e) for the
default, error, action or omission of either party to the escrow. Escrow Agent,
in its capacity as escrow agent, shall be entitled to rely on any document or
paper received by it, believed by such Escrow Agent, in good faith, to be bona
fide and genuine. In the event of any dispute as to the disposition of the
Deposit or any other monies held in escrow, or of any documents held in escrow,
Escrow Agent may, if such Escrow Agent so elects, interplead the matter by
filing an interpleader action in a court of general jurisdiction in the county
or circuit where the Real Property is located (to the jurisdiction of which both
parties do hereby consent), and pay into the registry of the court the Deposit,
or deposit any such documents with respect to which there is a dispute in the
Registry of such court, whereupon such Escrow Agent shall be relieved and
released from any further liability as Escrow Agent hereunder. Escrow Agent
shall not be liable for Escrow Agent's compliance with any legal process,
subpoena, writ, order, judgment and decree of any court, whether issued with or
without jurisdiction, and whether or not subsequently vacated, modified, set
aside or reversed.

         10.10 Incorporation by Reference. All of the exhibits attached hereto
are by this reference incorporated herein and made a part hereof.

         10.11 Survival. All of the representations, warranties, covenants and
agreements of Prentiss and Grande B made in, or pursuant to, this Agreement
shall survive Closing through the period ending twelve (12) months thereafter
and shall not merge into the Deed or any other document or instrument executed
and delivered in connection herewith; provided, however, the covenants in the
last sentence of Section 2.4(b) and Section 7.6 shall survive for the time
period described in such Sections, and the covenants in Sections 6.6 and 7.8 and
the indemnities in this Agreement shall have an unlimited survival period. In
the event a claim for indemnity is asserted in good faith prior to the
expiration of the applicable survival period, the claim may be asserted and the
indemnity shall continue notwithstanding the expiration of the survival period.

         10.12 Further Assurances. Prentiss and Grande B each covenant and agree
to sign, execute and deliver, or cause to be signed, executed and delivered, and
to do or make, or cause to be done or made, upon the written request of the
other party, any and all agreements, instruments, papers, deeds, acts or things,
supplemental, confirmatory or otherwise, as may be reasonably required by either

                                       37
<PAGE>

party hereto for the purpose of or in connection with consummating the
transactions described herein. Prentiss agrees to promptly correct any defect,
error or omission which may be discovered in the contents of this Agreement or
in any of the Exhibits or Schedules hereto.

         10.13 No Partnership. This Agreement does not and shall not be
construed to create a partnership, joint venture or any other relationship
between the parties hereto except the relationship of Prentiss and Grande B
specifically established hereby.

         10.14 Time of Essence. Time is of the essence with respect to every
provision hereof.

         10.15 Signatory Exculpation. The signatory(ies) for Prentiss, Grande B
and Brandywine OP are executing this Agreement in his/their capacity as
representative of Prentiss, Grande B and Brandywine OP, respectively, and not
individually and, therefore, shall have no personal or individual liability of
any kind in connection with this Agreement and the transactions contemplated by
it. No recourse shall be had for any obligation of Prentiss, Grande B or
Brandywine OP under this Agreement or under any document executed in connection
herewith or pursuant hereto, or for any claim based thereon or otherwise in
respect thereof, against any past, present or future trustee, shareholder,
officer or employee of Brandywine Realty Trust, Prentiss Properties Trust,
Grande B, Prentiss or Brandywine OP, whether by virtue of any statute or rule of
law, or by the enforcement of any assessment or penalty or otherwise, all such
liability being expressly waived and released by the parties hereto and all
parties claiming by, through or under them.

         10.16 Rules of Construction. The following rules shall apply to the
construction and interpretation of this Agreement:

               (a)  Singular words shall connote the plural number as well as
the singular and vice versa, and the masculine shall include the feminine and
the neuter.

               (b)  All references herein to particular articles, sections,
subsections, clauses or exhibits are references to articles, sections,
subsections, clauses or exhibits of this Agreement.

               (c)  The table of contents and headings contained herein are
solely for convenience of reference and shall not constitute a part of this
Agreement nor shall they affect its meaning, construction or effect.

               (d)  Each party hereto and its counsel have reviewed and revised
(or requested revisions of) this Agreement and have participated in the
preparation of this Agreement, and therefore any usual rules of construction
requiring that ambiguities are to be resolved against a particular party shall
not be applicable in the construction and interpretation of this Agreement or
any exhibits hereto.

               (e)  As used herein, the term or phrases "Effective Date," "date
of this Agreement" or "date hereof" shall mean the first date Escrow Agent is in
receipt of this Agreement executed by Prentiss and Grande B.

                                       38
<PAGE>

         10.17 Like-Kind Exchange. Prentiss agrees to cooperate reasonably with
Grande B in effecting an exchange transaction which includes the Property,
pursuant to Section 1031 of the United States Internal Revenue Code, provided
that any such exchange transaction, and the related documentation, shall: (a) be
at the sole cost and expense of Grande B; (b) not require Prentiss to execute
any contract, make any commitment, or incur any obligations, contingent or
otherwise, to third parties; (c) not delay the Closing; (d) not include Prentiss
becoming involved in a transaction with a third party; and (e) not otherwise be
contrary to or inconsistent with the terms of this Agreement.

         10.18 SEC Reporting (8-K) Requirements. For the period of time
commencing on the date hereof and continuing through the second anniversary of
the Closing Date, and without limitation of other document production otherwise
required of Prentiss hereunder, Prentiss shall, from time to time, upon
reasonable advance written notice from Grande B, provide Grande B and its
representatives, with access to all financial and other information pertaining
to the period of Prentiss' ownership and operation of the Property, which
information is relevant and reasonably necessary, in the opinion of outside,
third party accountants (the "Accountants") for Grande B, to enable Grande B and
its Accountants to prepare financial statements in compliance with any or all of
(a) Rule 3-05 or 3-14 of Regulation S-X of the Securities and Exchange
Commission (the "Commission"), as applicable; (b) any other rule issued by the
Commission and applicable to Brandywine OP or Brandywine Realty Trust
("Brandywine"); and (c) any registration statement, report or disclosure
statement filed with the Commission by Brandywine; and a representation letter,
signed by the individual(s) responsible for Prentiss' financial reporting, as
prescribed by generally accepted auditing standards promulgated by the Auditing
Standards Division of the American Institute of Certified Public Accountants,
which representation letter may be required by the Accountants in order to
render an opinion concerning Grande B's, Brandywine OP's or Brandywine's
financial statements.

                                       39
<PAGE>

         IN WITNESS WHEREOF, Prentiss and Grande B have caused this Agreement to
be executed in their names by their respective duly authorized representatives.

                               GRANDE B:

                               BRANDYWINE GRANDE B, L.P., a Delaware
                               limited partnership

                               By: BRANDYWINE GRANDE B CORP.,
                                   a Delaware corporation, its general partner

                                   By:    /s/ Gerard H. Sweeney
                                          --------------------------------------
                                   Title: President and Chief Executive Officer
                                          --------------------------------------

                                   Date of Execution: March 14, 2001

                               PRENTISS:

                               PRENTISS PROPERTIES ACQUISITION
                               PARTNERS, L.P., a Delaware limited partnership

                               By: Prentiss Properties I, Inc., a Delaware
                                   corporation, its general partner

                                   By:    /s/ Thomas F. August
                                          --------------------------------------
                                   Title: President and Chief Executive Officer
                                          --------------------------------------

                                   Date of Execution: March 14, 2001

         Brandywine OP is executing this Agreement for the purpose of (a)
consenting to the provisions of Article IV of this Agreement, and (b) agreeing
to guaranty all indemnities of Grande B in this Agreement and all documents
executed in connection with this Agreement.

                               BRANDYWINE OPERATING PARTNERSHIP, L.P.

                               By: Brandywine Realty Trust, its general partner

                                   By:    /s/ Gerard H. Sweeney
                                          --------------------------------------
                                   Title: President and Chief Executive Officer
                                          --------------------------------------

                                       40
<PAGE>

                             RECEIPT OF ESCROW AGENT

         Chicago Title Insurance Company, as Escrow Agent, acknowledges receipt
of the sum of $700,050.00 by check or by wire transfer, from Grande B as
described in Section 2.3 of the foregoing Exchange Agreement, said check or wire
transfer to be held pursuant to the terms and provisions of said Agreement.

         DATED this _____ day of __________, 2001.

                                   CHICAGO TITLE INSURANCE COMPANY

                                   By:__________________________________________

                                   Name:________________________________________

                                   Title:_______________________________________

                                       41

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