BRANDYWINE REALTY TRUST
8-K, 1997-07-23
REAL ESTATE INVESTMENT TRUSTS
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<PAGE>

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM 8-K

                                 Current Report

                       Pursuant to Section 13 or 15(d) of
                       The Securities Exchange Act of 1934

         Date of Report (Date of earliest event reported) July 15, 1997

                             BRANDYWINE REALTY TRUST
             (Exact name of registrant as specified in its charter)

           MARYLAND                  1-9106                23-2413352
(State or other jurisdiction   (Commission file  (I.R.S. Employer Identification
       of incorporation)             number)                 Number)
      
             16 Campus Boulevard, Newtown Square, Pennsylvania 19073
                    (Address of principal executive offices)

                                 (610) 325-5600
              (Registrant's telephone number, including area code)


                                Page 1 of 4 pages
<PAGE>

Item 5. Other Events.

I. On December 2, 1996, the Company obtained an $80.0 million revolving credit
facility (the "Credit Facility"). On July 15, 1997, the Company increased the
amount available for borrowing under the Credit Facility to up to $150.0
million. The lenders under the Credit Facility currently consist of NationsBank,
N.A., Smith Barney Mortgage Capital Group, Inc., Mellon Bank, N.A., The First
National Bank of Chicago, PNC Bank, National Association, Signet Bank and Summit
Bank, N.A. The Credit Facility bears interest at a per annum floating rate equal
to the 30, 60 or 90-day LIBOR, plus 175 basis points. The Credit Facility
requires monthly payments of interest only, with all outstanding advances and
all accrued but unpaid interest due December 1, 1998. The Credit Facility is a
recourse obligation of the Company and its subsidiaries, secured by, among other
things, cross-collateralized and cross-defaulted first mortgage liens on 61 of
the properties owned by the Company and its subsidiaries. Upon consummation of
the increase in the Credit Facility, the Company repaid all amounts outstanding,
together with accrued interest, under a $70.0 million secured credit facility
that the Company obtained on May 30, 1997 and which was scheduled to mature on
July 30, 1997. A commitment fee equal to $385,000 was paid to the lenders at the
closing of the increase. In addition, a fee of 0.25% per annum on the unused
amount of the Credit Facility is payable quarterly in arrears. An annual fee of
$35,000 is payable to NationsBank, N.A. for administration of the Credit
Facility. The Credit Facility includes loan to value, minimum debt service
coverage, fixed charge, net worth ratios and other financial covenants and
tests, minimum occupancy requirements and requires prepayment premiums in
certain instances.

      Subject to detailed terms, conditions and limitations contained in the
Credit Facility documents, proceeds of the Credit Facility will be available (i)
to refinance properties from time to time added to the collateral pool of the
Credit Facility, (ii) to finance the acquisition of additional properties, (iii)
to finance the acquisition and development of unimproved land, (iv) to finance
the renovation of and capital improvements required at properties of the Company
and its subsidiaries (whether or not part of the collateral pool for the Credit
Facility), (v) general trust, corporate and partnership purposes of the Company
and its subsidiaries, and (vi) for the issuance of letters of credit (as
described below); provided that the principal balance outstanding under the
Credit Facility for renovation and capital improvements and general trust,
corporate and partnership purposes and the amount available for draw under
outstanding letters of credit issued under the Credit Facility shall at no time
exceed $10 million in the aggregate, and provided further that the aggregate
principal balance outstanding under the Credit Facility, and the aggregate
amount available for draw under such outstanding letters of credit, shall at no
time exceed the maximum amount available under the Credit Facility from time to
time.

      The Credit Facility provides a mechanism for the issuance of letters of
credit on behalf of the Company and its subsidiaries, subject to the limitation,
among others, that each such credit shall be in an amount not less than
$100,000, and subject to the further 
<PAGE>

limitation, among others, that at no time during the term of the Credit Facility
shall there be more than five (5) letters of credit in the aggregate then
outstanding. The amount available for draw under outstanding letters of credit
may at no time exceed $10 million. The Credit Facility requires that all letter
of credit fees are to be paid in full on the date of issuance.

      The Credit Facility contains provisions limiting the amount of other
secured and unsecured debt maintained by the Company and its subsidiaries from
time to time.

      The Credit Facility contains detailed provisions regarding compliance with
environmental laws. The Company and several of its subsidiaries have also
delivered to the co-lenders a certain Hazardous Material Guaranty and
Indemnification Agreement with respect to properties constituting collateral for
the Credit Facility.

II. On July 22, 1997, the Company and Brandywine Operating Partnership, L.P.
entered into an Underwriting Agreement (the "Underwriting Agreement") with Smith
Barney Inc., Donaldson, Lufkin & Jenrette Securities Corporation, Legg Mason
Wood Walker, Incorporated and Merrill Lynch, Pierce, Fenner & Smith Incorporated
(collectively, the "Underwriters") pursuant to which the Company agreed to sell
to the Underwriters an aggregate of 10,000,000 common shares of beneficial
interest, $.01 par value per share (the "Common Shares"). In addition, the
Company granted the Underwriters an option to purchase up to an additional
1,500,000 Common shares solely to cover over-allotments, if any. The Common
Shares are to be sold pursuant to the Underwriting Agreement at a price to the
public of $20.75 per share ($19.66 after reduction for underwriting discounts
and commissions). Such net proceeds, less expenses estimated at $350,000, will
be contributed by the Company to the Operating Partnership, which will use such
contribution to repay borrowings under the Company's revolving Credit Facility,
and for working capital purposes. Closing of the offering of Common Shares
pursuant to the Underwriting Agreement is subject to customary closing
conditions.

Item 7. Financial Statements, Pro Forma Financial Information and Exhibits.

(c) Exhibits.

1.1 Underwriting Agreement among the Company, Brandywine Operating Partnership,
L.P., Smith Barney Inc., Donaldson, Lufkin & Jenrette Securities Corporation,
Legg Mason Wood Walker, Incorporated and Merrill Lynch, Pierce, Fenner & Smith
Incorporated.

10.1 First Amendment to Revolving Credit Facility Agreement and Other Credit
Facility Documents dated as of July 15, 1997, and related exhibits.
<PAGE>

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

                                            BRANDYWINE REALTY TRUST
                                           
                                           
Date: July 23, 1997                         By: /s/ Gerard H. Sweeney
                                                --------------------------------
                                            Title: President and Chief Executive
                                                      Officer
                                       

<PAGE>
                                                                     Exhibit 1.1

                                10,000,000 Shares

                             BRANDYWINE REALTY TRUST

                      Common Shares of Beneficial Interest

                             UNDERWRITING AGREEMENT

                                                                   July 22, 1997

SMITH BARNEY INC.
DONALDSON, LUFKIN & JENRETTE
  SECURITIES CORPORATION
LEGG MASON WOOD WALKER, INCORPORATED
MERRILL LYNCH, PIERCE, FENNER & SMITH
  INCORPORATED

c/o SMITH BARNEY INC.
    388 Greenwich Street
    New York, New York 10013

Dear Sirs:

      Brandywine Realty Trust, a Maryland real estate investment trust (the
"Company"), proposes to issue and sell an aggregate of 10,000,000 shares (the
"Firm Shares") of its common shares of beneficial interest, par value $0.01 per
share (the "Common Shares"), to you (collectively, the "Underwriters"). The
Company also proposes to sell to the Underwriters, upon the terms and conditions
set forth in Section 2 hereof, up to an additional 1,500,000 Common Shares (the
"Additional Shares"). The Firm Shares and the Additional Shares are hereinafter
collectively referred to as the "Shares."

      The Company, directly and through a wholly-owned subsidiary, is the sole
general partner and a limited partner (with an aggregate 96.883% ownership
interest as of the date hereof, without giving effect to the issuance and sale
of any Shares hereunder) of Brandywine Operating Partnership, L.P., a Delaware
limited partnership (the "Operating Partnership"). The Company will contribute
the net proceeds of the sale of the Firm Shares and the Additional Shares to the
Operating Partnership in exchange for additional partnership interests in the
Operating Partnership. The Company and the Operating Partnership wish to confirm
as follows their agreement with you, in connection with the several purchases of
the Shares by the Underwriters.
<PAGE>

      1. Registration Statement and Prospectus. The Company has prepared and
filed with the Securities and Exchange Commission (the "Commission") in
accordance with the provisions of the Securities Act of 1933, as amended, and
the rules and regulations of the Commission thereunder (collectively, the
"Act"), a registration statement on Form S-3 (Registration No. 333- 20991) under
the Act (the "registration statement"), including a prospectus generally
relating to the Shares; and such amendments, if any, to such registration
statement as may have been required prior to the date hereof have been filed
with the Commission, and such amendments, if any, have been similarly prepared.
Such registration statement and any post-effective amendments thereto have
become effective under the Act. The Company also has filed with the Commission
pursuant to Rule 424(b) under the Act, a prospectus supplement relating to the
Shares dated June 30, 1997 and has filed, or proposes to file, with the
Commission a second prospectus supplement specifically relating to the Shares
dated the date hereof.

      The term "Registration Statement" as used in this Agreement means the
registration statement (including all financial schedules and exhibits), as
amended at the time it became effective, or, if the registration statement
became effective prior to the execution of this Agreement, as supplemented or
amended prior to the execution of this Agreement, including all information (if
any) deemed to be a part of such registration at the time it became effective
pursuant to Rule 430A under the Act. If it is contemplated, at the time this
Agreement is executed, that a post-effective amendment to the registration
statement will be filed and must be declared effective before the offering of
the Shares may commence, the term "Registration Statement" as used in this
Agreement means the registration statement as amended by said post-effective
amendment. The term "Prospectus" as used in this Agreement means the base
prospectus included in the Registration Statement at the time it was declared
effective, or, if the prospectus included in the Registration Statement omits
information in reliance on Rule 430A under the Act and such information is
included in a prospectus filed with the Commission pursuant to Rule 424(b) under
the Act, the term "Prospectus" as used in this Agreement means the prospectus in
the form included in the Registration Statement as supplemented by the addition
of the Rule 430A information contained in the prospectus filed with the
Commission pursuant to Rule 424(b). The term "Prepricing Prospectus" as used in
this Agreement means the prospectus subject to completion in the form included
in the registration statement at the time of the initial filing of the
registration statement with the Commission, and as such prospectus shall have
been amended or supplemented from time to time prior to the date of the
Prospectus. Any reference in this Agreement to the registration statement, the
Registration Statement, any Prepricing Prospectus or the Prospectus shall be
deemed to refer to and include the documents incorporated by reference therein
pursuant to Item 12 of Form S-3 under the Act, as of the date of the
registration statement, the Registration Statement, such Prepricing Prospectus
or the Prospectus, as the case may be, and any reference to any amendment or
supplement to the registration statement, the Registration Statement, any
Prepricing Prospectus or the Prospectus shall be deemed to refer to and include
any documents filed after such date under the Securities Exchange Act of 1934,
as amended (the "Exchange Act") which, upon filing, are incorporated by
reference therein, as required by paragraph (b) of Item 12 of Form S-3. As used
herein, the term "Incorporated Documents" means the documents which at the time
are incorporated by reference in the registration statement, the Registration
Statement, any Prepricing Prospectus, the Prospectus, or any amendment or
supplement thereto. Capitalized terms used, but not defined, herein shall have
the respective meanings ascribed thereto in the Prospectus.


                                       -2-
<PAGE>

      2. Agreements to Sell and Purchase. The Company hereby agrees, subject to
all the terms and conditions set forth herein, to issue and sell to each
Underwriter and, upon the basis of the representations, warranties and
agreements of the Company and the Operating Partnership herein contained and
subject to all the terms and conditions set forth herein, each Underwriter
agrees, severally and not jointly, to purchase from the Company, at a purchase
price of $19.66 per Share (the "purchase price per share"), the number of Firm
Shares set forth opposite the name of such Underwriter in Schedule I hereto (or
such number of Firm Shares increased as set forth in Section 11 hereof).

      The Company also agrees, subject to all the terms and conditions set forth
herein, to sell to the Underwriters, and, upon the basis of the representations,
warranties and agreements of the Company and the Operating Partnership herein
contained and subject to all the terms and conditions set forth herein, the
Underwriters shall have the right to purchase from the Company, at the purchase
price per share, pursuant to an option (the "over-allotment option") which may
be exercised at any time and from time to time prior to 9:00 P.M., New York City
time, on the 30th day after the date of the Prospectus (or, if such 30th day
shall be a Saturday or Sunday or a holiday, on the next business day thereafter
when the American Stock Exchange is open for trading), up to an aggregate of
1,500,000 Additional Shares. Additional Shares may be purchased only for the
purpose of covering over-allotments made in connection with the offering of the
Firm Shares. Upon any exercise of the over-allotment option, each Underwriter,
severally and not jointly, agrees to purchase from the Company the number of
Additional Shares (subject to such adjustments as you may determine in order to
avoid fractional shares) which bears the same proportion to the number of
Additional Shares to be purchased by the Underwriters as the number of Firm
Shares set forth opposite the name of such Underwriter in Schedule I hereto (or
such number of Firm Shares increased as set forth in Section 11 hereof) bears to
the aggregate number of Firm Shares.

      3. Terms of Public Offering. The Company has been advised by you that you
propose to make a public offering of your respective portions of the Shares as
soon after the Registration Statement and this Agreement have become effective
as in your judgment is advisable and initially to offer the Shares upon the
terms set forth in the Prospectus.

      4. Delivery of the Shares and Payment Therefor. Delivery to the
Underwriters of and payment for the Firm Shares shall be made at the office of
Smith Barney Inc., 388 Greenwich Street, New York, NY 10013, at 10:00 A.M., New
York City time, on July 28, 1997 (the "Closing Date"). The place of closing for
the Firm Shares and the Closing Date may be varied by agreement between you and
the Company.

      Delivery to the Underwriters of and payment for any Additional Shares to
be purchased by the Underwriters shall be made at the aforementioned office of
Smith Barney Inc. at such time on such date (the "Option Closing Date"), which
may be the same as the Closing Date but shall in no event be earlier than the
Closing Date nor earlier than two nor later than ten business days after the
giving of the notice hereinafter referred to, as shall be specified in a written
notice from you to the Company of your determination to purchase a number,
specified in such notice, of Additional Shares. The place of closing for any
Additional Shares and the Option Closing Date for such Shares may be varied by
agreement between you and the Company.


                                       -3-
<PAGE>

      Certificates for the Firm Shares and for any Additional Shares to be
purchased hereunder shall be registered in such names and in such denominations
as you shall request prior to 9:30 A.M., New York City time, on the second
business day preceding the Closing Date or any Option Closing Date, as the case
may be. Such certificates shall be made available to you in New York City for
inspection and packaging not later than 9:30 A.M., New York City time, on the
business day next preceding the Closing Date or the Option Closing Date, as the
case may be. The certificates evidencing the Firm Shares and any Additional
Shares to be purchased hereunder shall be delivered to you on the Closing Date
or the Option Closing Date, as the case may be, against payment of the purchase
price therefor by wire transfer of immediately available funds to the Company.

      5. Agreements of the Company and the Operating Partnership. The Company
and the Operating Partnership jointly and severally agree with the several
Underwriters as follows:

            (a) If, at the time this Agreement is executed and delivered, it is
necessary for the Registration Statement or a post-effective amendment thereto
to be declared effective before the offering of the Shares may commence, the
Company will endeavor to cause the Registration Statement or such post-effective
amendment to become effective as soon as possible and will advise you promptly
and, if requested by you, will confirm such advice in writing, when the
Registration Statement or such post-effective amendment has become effective.

            (b) The Company will advise you promptly and, if requested by you,
will confirm such advice in writing: (i) of any request by the Commission for
amendment of or a supplement to the Registration Statement, any Prepricing
Prospectus or the Prospectus or for additional information; (ii) of the issuance
by the Commission of any stop order suspending the effectiveness of the
Registration Statement or of the suspension of qualification of the Shares for
offering or sale in any jurisdiction or the initiation of any proceeding for
such purpose; and (iii) within the period of time referred to in paragraph (f)
below, of any change in the Company's condition (financial or other), business,
prospects, properties, net worth or results of operations, or of the happening
of any event, which makes any statement of a material fact made in the
Registration Statement or the Prospectus (as then amended or supplemented)
untrue or which requires the making of any additions to or changes in the
Registration Statement or the Prospectus (as then amended or supplemented) in
order to state a material fact required by the Act or the regulations thereunder
to be stated therein or necessary in order to make the statements therein not
misleading, or of the necessity to amend or supplement the Prospectus (as then
amended or supplemented) to comply with the Act or any other law. If at any time
the Commission shall issue any stop order suspending the effectiveness of the
Registration Statement, the Company will make every reasonable effort to obtain
the withdrawal of such order at the earliest possible time.

            (c) The Company will furnish to you, without charge, (i) five copies
of the registration statement as originally filed with the Commission and of
each amendment thereto, including financial statements and all exhibits to the
registration statement, (ii) such number of copies of the Prepricing Prospectus
or Prospectus as you may reasonably request, (iii) such number of copies of the
Incorporated Documents, as you may reasonably request, and (iv) such number of
conformed copies of the Registration Statement and of each amendment thereto,
but without exhibits, as you may reasonably request.


                                       -4-
<PAGE>

            (d) The Company will not file any amendment to the Registration
Statement or make any amendment or supplement to the Prospectus or, prior to the
end of the period of time referred to in the first sentence of subsection (f)
below, file any document which upon filing becomes an Incorporated Document, of
which you shall not previously have been advised or to which, after you shall
have received a copy of the document proposed to be filed, you shall object.

            (e) Prior to the execution and delivery of this Agreement, the
Company has delivered to you, without charge, in such quantities as you have
reasonably requested, copies of each form of the Prepricing Prospectus. The
Company consents to the use, in accordance with the provisions of the Act and
with the securities or Blue Sky or real estate syndication laws of the
jurisdictions in which the Shares are offered by the several Underwriters and by
dealers, prior to the date of the Prospectus, of each Prepricing Prospectus so
furnished by the Company.

            (f) As soon after the execution and delivery of this Agreement as
possible and thereafter from time to time for such period as in the opinion of
counsel for the Underwriters a prospectus is required by the Act to be delivered
in connection with sales by any Underwriter or dealer, the Company will
expeditiously deliver to each Underwriter and each dealer, without charge, as
many copies of the Prospectus (and of any amendment or supplement thereto) as
you may request. The Company consents to the use of the Prospectus (and of any
amendment or supplement thereto) in accordance with the provisions of the Act
and with the securities or Blue Sky or real estate syndication laws of the
jurisdictions in which the Shares are offered by the several Underwriters and by
all dealers to whom Shares may be sold, both in connection with the offering and
sale of the Shares and for such period of time thereafter as the Prospectus is
required by the Act to be delivered in connection with sales by any Underwriter
or dealer. If during such period of time any event shall occur that in the
judgment of the Company or in the opinion of counsel for the Underwriters is
required to be set forth in the Prospectus (as then amended or supplemented) or
should be set forth therein in order to make the statements therein, in the
light of the circumstances under which they were made, not misleading, or if it
is necessary to supplement or amend the Prospectus (or to file under the
Exchange Act any document which, upon filing, becomes an Incorporated Document)
in order to comply with the Act or any other law, the Company will forthwith
prepare and, subject to the provisions of paragraph (d) above, file with the
Commission an appropriate supplement or amendment thereto (or to such document),
and will expeditiously furnish to the Underwriters and dealers a reasonable
number of copies thereof. In the event that the Company and you agree that the
Prospectus should be amended or supplemented, the Company, if requested by you,
will promptly issue a press release announcing or disclosing the matters to be
covered by the proposed amendment or supplement.

            (g) The Company will cooperate with you and with counsel for the
Underwriters in connection with the registration or qualification of the Shares
for offering and sale by the several Underwriters and by dealers under the
securities or Blue Sky or real estate syndication laws of such jurisdictions as
you may designate and will file such consents to service of process or other
documents necessary or appropriate in order to effect such registration or
qualification; provided that in no event shall the Company be obligated to
qualify to do business in any jurisdiction where it is not now so qualified or
to take any action which would subject it to service of process in suits, other
than those arising out of the offering or sale of the Shares, in any
jurisdiction where it is not now so subject.


                                       -5-
<PAGE>

            (h) The Company will make generally available to its security
holders a consolidated earnings statement, which need not be audited, covering a
twelve-month period commencing after the effective date of the Registration
Statement and ending not later than 15 months thereafter, as soon as practicable
after the end of such period, which consolidated earnings statement shall
satisfy the provisions of Section 11(a) of the Act.

            (i) During the period of five years hereafter, the Company will
furnish to you (i) as soon as available, a copy of each report of the Company
mailed to stockholders or filed with the Commission, and (ii) from time to time
such other information concerning the Company as you may reasonably request.

            (j) If this Agreement shall terminate or shall be terminated after
execution pursuant to any provisions hereof (otherwise than pursuant to Section
11 hereof or by notice given by you terminating this Agreement pursuant to
Section 11 or Section 12 hereof) or if this Agreement shall be terminated by the
Underwriters because of any failure or refusal on the part of the Company to
comply with the terms or fulfill any of the conditions of this Agreement, the
Company agrees to reimburse you for all out-of-pocket expenses (including fees
and expenses of counsel for the Underwriters) incurred by you in connection
herewith.

            (k) The Company will apply the net proceeds from the sale of the
Shares in accordance with the description set forth in the Prospectus.

            (l) The Company will timely file with the Commission the Prospectus
pursuant to Rule 424(b) under the Act and will advise you of the time and manner
of such filing.

            (m) Except as provided or described in this Agreement or in the
Prospectus, neither the Company nor the Operating Partnership will sell, offer
to sell, solicit an offer to buy, contract to sell or otherwise transfer or
dispose of any Common Shares or any securities convertible into or exercisable
or exchangeable for Common Shares (whether through the issuance or granting of
any options, warrants, commitments, subscriptions, rights to purchase or
otherwise) for a period of 90 days after the date of the Prospectus, without the
prior written consent of Smith Barney Inc.; provided, however, that the
foregoing shall not prohibit (i) the Company or the Operating Partnership from
issuing Common Shares, limited partner interests in the Operating Partnership
("Units"), or other securities exchangeable for or redeemable into Common Shares
in connection with the acquisition of any office or industrial property or an
equity interest in any such property, (ii) the Company from issuing Common
Shares upon the exercise or conversion of any Units or any options or warrants
of the Company outstanding on the date hereof, (iii) the Company from issuing
Common Shares to non-employee trustees of the Company as compensation for their
participation on the Company's board of trustees, and (iv) awards under the
Company's 1997 Long-Term Incentive Plan to employees of the Company other than
those named in the Prospectus.

            (n) The Company has furnished to you "lock-up" letters, in form and
substance satisfactory to you, signed by each of its current officers and
trustees and each of its stockholders designated by you.


                                       -6-
<PAGE>

            (o) Except as stated in this Agreement and in any Prepricing
Prospectus and Prospectus, the Company has not taken, nor will it take, directly
or indirectly, any action designed to or that might reasonably be expected to
cause or result in stabilization or manipulation of the price of the Common
Shares to facilitate the sale or resale of the Shares.

      6. Representations and Warranties of the Company. The Company and the
Operating Partnership, jointly and severally, represent and warrant to each
Underwriter that:

            (a) Each Prepricing Prospectus included as part of the registration
statement as originally filed or as part of any amendment or supplement thereto,
or filed pursuant to Rule 424 under the Act, complied when so filed in all
material respects with the provisions of the Act. The Commission has not issued
any order suspending the effectiveness of the Registration Statement or any part
thereof and no proceeding for that purpose has been instituted or threatened or,
to the best knowledge of the Company, contemplated by the Commission or the
securities authority of any state or other jurisdiction.

            (b) The Company and the transactions contemplated by this Agreement
meet the requirements and conditions for using a registration statement on Form
S-3 under the Act. When any Prepricing Prospectus was filed with the Commission
it (i) contained all statements required to be stated therein in accordance
with, and complied in all material respects with the requirements of, the Act
and the rules and regulations of the Commission thereunder and (ii) did not
include any untrue statement of a material fact or omit to state any material
fact necessary in order to make the statements therein, in the light of the
circumstances under which they were made, not misleading. When the Registration
Statement or any amendment thereto was declared effective, and on the Closing
Date (or the Option Closing Date, as the case may be) it (i) contained or will
contain all statements required to be stated therein in accordance with, and
complied or will comply in all material respects with the requirements of, the
Act and the rules and regulations of the Commission thereunder and (ii) did not
or will not include any untrue statement of a material fact or omit to state any
material fact necessary to make the statements therein not misleading. When the
Prospectus or any amendment or supplement thereto is filed with the Commission
pursuant to Rule 424(b) and at the Closing Date (or the Option Closing Date, as
the case may be), the Prospectus, as amended or supplemented at any such time,
(i) contained or will contain all statements required to be stated therein in
accordance with, and complied or will comply in all material respects with the
requirements of, the Act and the rules and regulations of the Commission
thereunder and (ii) did not or will not include any untrue statement of a
material fact or omit to state any material fact necessary in order to make the
statements therein, in the light of the circumstances under which they were
made, not misleading. The representations and warranties in this paragraph (b)
do not apply to statements in or omissions from the Registration Statement or
the Prospectus made in reliance upon and in conformity with information
furnished to the Company in writing by or on behalf of any Underwriter through
you expressly for use therein.

            (c) The Incorporated Documents heretofore filed, when they were
filed (or, if any amendment with respect to any such document was filed, when
such amendment was filed), conformed in all material respects with the
requirements of the Exchange Act and the rules and regulations thereunder, any
further Incorporated Documents so filed will, when they are filed, conform in
all material respects with the requirements of the Exchange Act and the rules
and


                                       -7-
<PAGE>

regulations thereunder, no such document when it was filed (or, if an amendment
with respect to any such document was filed, when such amendment was filed),
contained an untrue statement of a material fact or omitted to state a material
fact required to be stated therein or necessary in order to make the statements
therein not misleading and no such further document, when it is filed, will
contain an untrue statement of a material fact or will omit to state a material
fact required to be stated therein or necessary in order to make the statements
therein not misleading.

            (d) The Company is a real estate investment trust duly formed and
validly existing under and by virtue of the laws of the State of Maryland and is
in good standing with the State Department of Assessments and Taxation of
Maryland, with full trust power and authority to own, lease, and operate its
properties (including the properties (the "Pending Acquisitions") described in
the Prospectus under the caption "Recent Developments - Pending Acquisitions" as
being subject to certain agreements of sale (the "Transaction Documents")), and
to conduct its business as described in the Registration Statement and the
Prospectus, and is duly registered and qualified to conduct its business and is
in good standing in each jurisdiction or place where the nature of its
properties or the conduct of its business (after taking into account the
purchase of the Pending Acquisitions) requires such registration or
qualification, except where the failure to be so registered or qualified would
not have a material adverse effect on the condition (financial or otherwise),
business, prospects, properties, net worth or results of operations of the
Company. The Transaction Documents are listed on Schedule 6(d) hereto.

            (e) Each of the Operating Partnership and the corporations,
partnerships and limited partnerships listed on Schedule 6(e) hereto (each, a
"Subsidiary") is a corporation, limited partnership, limited liability company
or general partnership duly incorporated or formed, as the case may be, validly
existing and in good standing under the laws of its jurisdiction of
incorporation or formation. Each such entity has full corporate or partnership
power and authority, to own, lease, and operate its properties, and to conduct
its business as described in the Registration Statement and the Prospectus. Each
such Subsidiary is duly registered and qualified to conduct its business and is
in good standing in each jurisdiction or place where the nature of its
properties or the conduct of its business requires such registration or
qualification, except where the failure to be so registered or qualified would
not have a material adverse effect on the condition (financial or otherwise),
business, prospects, properties, net worth or results of operations of such
Subsidiary.

            (f) All the outstanding Common Shares of the Company have been duly
authorized and validly issued, are fully paid and nonassessable and are free of
any preemptive or similar rights; the Shares have been duly authorized and, when
issued and delivered to the Underwriters against payment therefor in accordance
with the terms hereof, will be validly issued, fully paid and nonassessable and
free of any preemptive or similar rights that entitle or will entitle any person
or entity to acquire any Shares upon the issuance thereof by the Company, and
the beneficial interest of the Company conforms to the description thereof in
the Registration Statement and the Prospectus. Except with regard to 1997
compensation of non-employee trustees of the Company payable in Common Shares,
awards under the the Company's 1997 Long-Term Incentive Plan and as disclosed in
the Prospectus, there are no outstanding options, warrants or other rights
calling for the issuance of, or any commitment, plan or arrangement to issue,
any beneficial interest of the Company or any security convertible into or
exchangeable for beneficial interest of the Company.


                                       -8-
<PAGE>

            (g) All of the outstanding Units and shares of capital stock or
partnership interests in each of the Subsidiaries have been duly authorized and
validly issued or created under the documents or agreements forming such entity,
are fully paid and, in the case of Subsidiaries that are corporations,
nonassessable, and will be owned or be held by the persons and entities in the
percentage amounts set forth and in the manner described in the Prospectus or
Schedule 6(g). Except as described in the Prospectus or Schedule 6(g), all such
Units, partnership interests and shares of capital stock are owned by the
Company directly, or indirectly through the Operating Partnership or one of the
other Subsidiaries, free and clear of any lien, adverse claim, security
interest, equity, or other encumbrance, and the Company's percentage interest
and ownership in the Operating Partnership, and the Company's and the Operating
Partnership's percentage interest and ownership in each of the Subsidiaries, is
as set forth on Schedule 6(g) attached hereto. Except as described in the
Registration Statement and the Prospectus (or any amendment or supplement
thereto), there are no outstanding options, warrants or other rights calling for
the issuance of, or any commitment, plan or arrangement to issue, any equity
interests in any Subsidiary, or any security convertible into, or exchangeable
or exercisable for, any such interests in any such Subsidiary. The terms of the
Units conform in all material respects to statements and descriptions thereof
contained in the Prospectus. The Company is the sole general partner of the
Operating Partnership and has sole voting, management and administrative control
of Brandywine Realty Partners.

            (h) The Company has no direct or indirect subsidiaries other than
the Subsidiaries. Other than the Subsidiaries, neither the Company nor the
Operating Partnership owns, directly or indirectly, more than 2% of the
securities of any corporation, partnership, joint venture, limited liability
company, association or other business association.

            (i) There are no actions, suits or proceedings pending or, to the
knowledge of the Company or the Operating Partnership, threatened against or
affecting the Company or any of the Subsidiaries, or any of their respective
partners, directors, trustees or officers in their capacity as such, or to which
the Company or any of the Subsidiaries or any of their respective partners,
directors, trustees or officers in their capacity as such, or to which any of
their respective properties is subject, that are required to be described in the
Registration Statement or the Prospectus but are not described as required, and
there are no agreements, contracts, indentures, leases or other instruments that
are required to be described in the Registration Statement or the Prospectus or
to be filed as an exhibit to the Registration Statement that are not described
or filed as required by the Act.

            (j) Neither the Company nor any of the Subsidiaries is in violation
of its Declaration of Trust, certificate or articles of incorporation or
by-laws, partnership agreement or other organizational documents, or of any law,
ordinance, administrative or governmental rule or regulation applicable to the
Company or any of the Subsidiaries or of any decree of any court or governmental
agency or body having jurisdiction over the Company or any of the Subsidiaries,
or in default in any material respect in the performance of any obligation,
agreement or condition contained in any bond, debenture, note or any other
evidence of indebtedness or in any agreement, indenture, lease or other
instrument to which the Company or any of the Subsidiaries is a party or by
which any of them or any of their respective properties may be bound.


                                       -9-
<PAGE>

            (k) Neither the issuance and offer, and sale or delivery of the
Shares, the execution, delivery or performance of this Agreement, nor the
consummation of the transactions contemplated hereby or thereby by the Company
or any Subsidiary, as applicable, (i) required or requires any consent,
approval, authorization or other order of or registration or filing with, any
court, regulatory body, administrative agency or other governmental body, agency
or official (except such as may be required for the registration of the Shares
under the Act and compliance with the securities or Blue Sky laws of various
jurisdictions, all of which have been or will be effected in accordance with
this Agreement), (ii) conflicted with, conflicts or will conflict with or
constituted, constitutes or will constitute a breach of, or a default under, the
Declaration of Trust, certificate or articles of incorporation or bylaws,
partnership agreement or other organizational documents, of the Company or any
of the Subsidiaries or under any agreement, indenture, lease or other instrument
to which the Company or any of the Subsidiaries is a party or by which any of
them or any of their respective properties may be bound, (iii) violated,
violates or will violate any statute, law, regulation or filing or judgment,
injunction, order or decree applicable to the Company or any of the Subsidiaries
or any of their respective properties, or (iv) resulted, results or will result
in the creation or imposition of any lien, charge or encumbrance upon any
property or assets of the Company or any of the Subsidiaries pursuant to the
terms of any agreement or instrument to which any of them is a party or by which
any of them may be bound or to which any of the property or assets of any of
them is subject.

            (l) All offers and sales of Units or other partnership interests in
the Operating Partnership, and the offer, sale or issuance by the Company of
Common Shares and Preferred Shares prior to the date hereof have been duly
registered under the Act, or were exempt from the registration requirements of
the Act and state securities and Blue Sky laws.

            (m) The accountants, Arthur Andersen LLP and Zelenkofske Axelrod &
Company, Ltd., who have audited the financial statements included or
incorporated by reference in the Registration Statement and the Prospectus (and
any amendment or supplement thereto), are independent public accountants as
required by the Act.

            (n) The financial statements, together with related schedules and
notes, included or incorporated by reference in the Registration Statement and
the Prospectus (and any amendment or supplement thereto), present fairly the
consolidated financial position, results of operations and changes in cash flows
of the respective entity, entities, property, or properties, as applicable, at
the respective dates or for the respective periods to which they apply; such
statements and related schedules and notes have been prepared in accordance with
generally accepted accounting principles consistently applied throughout the
periods involved, and comply with the applicable accounting requirements of the
Act (including, without limitation, Rule 3-14 of Regulation S-X promulgated by
the Commission). The other financial and statistical information and data
included in the Registration Statement and the Prospectus (and any amendment or
supplement thereto) are accurately presented and prepared on a basis consistent
with such financial statements and the books and records of the relevant entity,
entities, property or properties, as applicable; any pro forma financial
statements of the Company included or incorporated by reference in the
Registration Statement and the Prospectus comply in all material respects with
the applicable requirements of Rule 11-02 of Regulation S-X of the Commission,
and any pro forma adjustments have been made upon management's reasonable good
faith estimates of the pro forma adjustments and have been properly applied to
the historical amounts in the compilation of such statements.


                                      -10-
<PAGE>

            (o) The Company has all trust power and authority, and the Operating
Partnership has all partnership power and authority, to enter into this
Agreement and each Transaction Document to which it is a party, and, in the case
of the Company, to issue, sell and deliver the Shares to the Underwriters as
provided in the Underwriting Agreement, and each of the Underwriting Agreement
and each Transaction Document has been duly and validly authorized, executed and
delivered by the Company and the Operating Partnership, as applicable, and, to
the knowledge of the Company, each of the other parties thereto, and is a valid,
legal and binding agreement of each of the Company and the Operating
Partnership, as applicable, enforceable against each of the Company and the
Operating Partnership in accordance with its terms, except as enforcement of
rights to indemnity and contribution hereunder may be limited by Federal or
state securities laws or principles of public policy.

            (p) Except as disclosed in the Registration Statement and the
Prospectus (or any amendment or supplement thereto), subsequent to the
respective dates as of which such information is given in the Registration
Statement and the Prospectus (or any amendment or supplement thereto), neither
the Company nor any of the Subsidiaries has incurred any liability or
obligation, direct or contingent, or entered into any transaction, not in the
ordinary course of business, that is material to the Company and the
Subsidiaries taken as a whole, and there has not been any change in the
beneficial interest or capital stock, or material increase in the short-term
debt or long-term debt, of the Company or any of the Subsidiaries, or any
material adverse change, or any development involving or which may reasonably be
expected to involve, a prospective material adverse change, in the condition
(financial or other), business, prospects, properties, net worth or results of
operations of the Company and the Subsidiaries taken as a whole.

            (q) Each of the Company or the Operating Partnership (either
directly or through a Subsidiary) has, and after giving effect to the
transactions described in the Registration Statement and Prospectus will have,
good and marketable and insurable title to all real property described in the
Prospectus as being or to be owned by it, free and clear of all liens, claims,
security interests or other encumbrances except such as are described in the
Registration Statement and the Prospectus or in a document filed as an exhibit
to, or incorporated by reference in, the Registration Statement. All the
property described in the Prospectus as being held under lease by each of the
Company and the Subsidiaries is held by it under valid, subsisting and
enforceable leases, other than those described in the Registration Statement and
the Prospectus and those which do not and will not have a material adverse
effect on the condition (financial or other), business, prospects, properties,
net worth or results of operations of the Company and the Subsidiaries taken as
a whole.

            (r) The Company has not distributed and, prior to the later to occur
of (i) the Closing Date and (ii) completion of the distribution of the Shares,
will not distribute any offering material in connection with the offering and
sale of the Shares other than the Registration Statement, the Prepricing
Prospectus, the Prospectus or other materials, if any, permitted by the Act.

            (s) Each of the Company and each of the Subsidiaries has, such
permits, licenses, franchises and authorizations of governmental or regulatory
authorities ("permits") as are necessary to own its respective properties and to
conduct its business in the manner described


                                      -11-
<PAGE>

in the Prospectus; each of the Company and each of the Subsidiaries has
fulfilled and performed all its material obligations with respect to such
permits and no event has occurred which allows, or after notice or lapse of time
would allow, revocation or termination thereof or results in any other material
impairment of the rights of the holder of any such permit, subject in each case
to such qualification as may be set forth in the Prospectus; and, except as
described in the Prospectus, none of such permits contains any restriction that
is materially burdensome to the Company or any of the Subsidiaries.

            (t) The Company together with the Subsidiaries maintains and will
maintain a system of internal accounting controls sufficient to provide
reasonable assurances that (i) transactions are executed in accordance with
management's general or specific authorization; (ii) transactions are recorded
as necessary to permit preparation of financial statements in conformity with
generally accepted accounting principles and to maintain accountability for
assets; (iii) access to assets is permitted only in accordance with management's
general or specific authorization; and (iv) the recorded accountability for
assets is compared with existing assets at reasonable intervals and appropriate
action is taken with respect to any differences.

            (u) Neither the Company nor any of its Subsidiaries nor any employee
or agent of the Company or any Subsidiary has made any payment of funds of the
Company or any Subsidiary or received or retained any funds in violation of any
law, rule or regulation, which payment, receipt or retention of funds is of a
character required to be disclosed in the Prospectus.

            (v) The Company and each of the Subsidiaries have filed all tax
returns required to be filed, which returns are complete and correct, and
neither the Company nor any Subsidiary is in default in the payment of any taxes
which were payable pursuant to said returns or any assessments with respect
thereto.

            (w) Except as described in the Prospectus, there is no holder of any
security of the Company, or the Operating Partnership or any other person who
has the right, contractual or otherwise, to cause the Company to sell or
otherwise issue to them, or to permit them to underwrite the sale of, the Shares
or the right to have any Common Shares or other securities of the Company
included in the Registration Statement or the right, as a result of the filing
of the registration statement or sale of the Shares as contemplated by this
Agreement, to require registration under the Act of any Common Shares or other
securities of the Company.

            (x) The Company and the Subsidiaries own or possess all patents,
trademarks, trademark registrations, service marks, service mark registrations,
trade names, copyrights, licenses, inventions, trade secrets and rights
described in the Prospectus as being owned by them or any of them or necessary
for the conduct of their respective businesses, and neither the Company nor the
Operating Partnership is aware of any claim to the contrary or any challenge by
any other person to the rights of the Company and the Subsidiaries with respect
to the foregoing.

            (y) None of the Company or any Subsidiary is now, and after sale of
the Shares to be sold by it hereunder and application of the net proceeds from
such sale as described in the Prospectus under the caption "Use of Proceeds"
will be, an "investment company," or entity


                                      -12-
<PAGE>

"controlled" by an "investment company," within the meaning of the Investment
Company Act of 1940, as amended.

            (z) The Company has filed in a timely manner each document or report
required to be filed by it pursuant to the Exchange Act and the rules and
regulations thereunder; each such document or report at the time it was filed
conformed to the requirements of the Exchange Act and the rules and regulations
thereunder; and none of such documents or reports contained an untrue statement
of any material fact or omitted to state any material fact required to be stated
therein or necessary to make the statements therein not misleading.

            (aa) The Company and its Subsidiaries are organized and operate in
the manner described in the Registration Statement so that the Company meets the
requirements for qualification as a real estate investment trust under Sections
856 through 860 of the Code and the rules and regulations thereunder as
currently in effect. Each Subsidiary that is a partnership or limited liability
company will be treated as a partnership, and not as an association taxable as a
corporation or a publicly traded partnership, for federal income tax purposes.

            (bb) The Shares are duly authorized for listing, subject to official
notice of issuance, on the American Stock Exchange.

            (cc) Except as described in the Prospectus or provided in the Credit
Facility, the mortgages and deeds of trust encumbering the Properties will not
be cross-defaulted or cross-collateralized with any other property not owned
directly or indirectly by the Company or any of the Subsidiaries.

            (dd) (1) Each of the Properties, the Company, and each of the
Subsidiaries (i) is, and as of the Closing Date will be, in compliance in all
material respects with any and all applicable foreign, federal, state and local
laws and regulations relating to the protection of human health and safety, the
environment or hazardous or toxic substances or wastes, pollutants or
contaminants ("Environmental Laws"), (ii) has received, or will have received,
as of the Closing Date, as the case may be, all licenses or other approvals
required of them under applicable Environmental Laws to conduct their respective
business, and (iii) is, and will be as of the Closing Date in material
compliance with all terms and conditions of any such permit, license or
approval.

                  (2) Except as may be specifically disclosed in the Phase I
Environmental Site Assessment reports referred to in the Prospectus (the
"Environmental Reports"), the Company and the Subsidiaries have not at any time,
and, to the knowledge of the Company, no other party has at any time, handled,
buried, stored, retained, refined, transported, processed, manufactured,
generated, produced, spilled, allowed to seep, leak, escape or leach, or be
pumped, poured, emitted, emptied, discharged, injected, dumped, transferred or
otherwise disposed of or dealt with, Hazardous Materials (as hereinafter
defined) on, to or from the Properties. The Company and the Subsidiaries do not
intend to use the Properties or any subsequently acquired properties for the
purpose of handling, burying, storing (except with respect to cleaning materials
reasonably used to operate the Properties in the ordinary course, in normal
quantities and in full compliance with law), retaining, refining, transporting,
processing, manufacturing, generating, producing, spilling, seeping, leaking,
escaping, leaching, pumping, pouring, emitting, emptying, discharging,
injecting, dumping, transferring or otherwise disposing of or dealing with
Hazardous Materials.


                                      -13-
<PAGE>

                  (3) Except as disclosed in the Environmental Reports, to the
knowledge of the Company, there has been no seepage, leaking, escape, leaching,
discharge, injection, release, emission, spill, pumping, pouring, emptying or
dumping of Hazardous Materials into waters on or adjacent to the Properties or
onto lands from which such hazardous or toxic waste or substances might seep,
flow or drain into such waters.

                  (4) Except as disclosed in the Environmental Reports, neither
the Company nor any Subsidiary has received notice of any occurrence or
circumstance which, with notice or passage of time or both, would give rise to
any claim under or pursuant to any Environmental Law pertaining to hazardous or
toxic waste or substances on or originating from the Properties or arising out
of the conduct of any such party.

                  (5) No environmental engineering firm which prepared the
Environmental Reports (or amendments thereto) or physical condition
(engineering) reports with respect to the Properties was employed for such
purpose on a contingent basis or has any substantial interest in the Company or
any Subsidiary.

            As used herein, "Hazardous Material" shall include, without
limitation, any flammable explosives, radioactive materials, hazardous
materials, hazardous wastes, hazardous or toxic substances or related materials,
asbestos or any related material as defined by any Federal, state or local
environmental law, ordinance, rule, or regulation including, without limitation,
Environmental Laws such as the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980, as amended (42 U.S.C. Section 9601, et
seq.), the Hazardous Materials Transportation Act, as amended (49 U.S.C. Section
1801, et seq.), the Resource Conservation and Recovery Act, as amended (42
U.S.C. Section 9601, et seq.), The New Jersey Industrial Site Recovery Act,
N.J.S.A.ss.13:1K-6, et seq. or and in the regulations adopted and publications
promulgated pursuant to each of the foregoing or by any Federal, state or local
Governmental authority having or claiming jurisdiction over the Properties as
described in the Prospectus.

            (ee) To the knowledge of the Company, all physical condition
(engineering) reports obtained for the Properties are materially true and
correct. Neither the Company nor any of the Subsidiaries is aware of any
material capital expenditures (other than expenditures for maintenance or tenant
improvements in the ordinary course of business) that will be required in
connection with any of the Properties prior to the fifth anniversary of this
Agreement, except with respect to the renovation of the 4000 Midlantic Drive
office building and the development of the Horsham Business Center.

            (ff) As of the Closing Date, the Company or the Operating
Partnership, as applicable, will have obtained ALTA Extended Coverage Owner's
Policies of Title Insurance (or its equivalent) from title insurers of
recognized financial responsibility on each of the Properties, in amounts at
least equal to the acquisition price of each such property (or, in the case of
the Property at Delaware Corporate Center I, the leasehold interest) (and
improvements located on each such property), and such insurance shall be in full
force and effect.


                                      -14-
<PAGE>

            (gg) The assets of the Company and the Subsidiaries do not, and as
of the Closing Date will not, constitute "plan assets" under the Employee
Retirement Income Security Act of 1974, as amended.

            (hh) Each partnership agreement, agreement of limited partnership,
other organizational or formation agreement, and each amendment thereto, of each
Subsidiary that is a general or limited partnership (the "Organizational
Documents") has been duly and validly authorized, executed and delivered by the
Company and the applicable Subsidiaries party thereto, and each such
Organizational Document constitutes the legal, valid and binding agreement of
each party thereto, enforceable against each such party in accordance with its
terms.

            (ii) Each of the agreements disclosed in the Prospectus under the
caption "Recent Developments -- Pending Acquisitions" as having been executed
has been executed and delivered by the seller thereunder and has been duly and
validly authorized, executed and delivered by each of the Company and the
Subsidiaries that is a party thereto, and each such agreement constitutes the
legal, valid and binding agreement of each such party thereto, enforceable
against each such party in accordance with its terms.

            (jj)  (i) The Company and its Subsidiaries have their respective
      principal business operations in the United States or its Territories.

                  (ii) The Company has a class of securities registered pursuant
      to Section 12(b) of the Exchange Act.

                  (iii) The Company (A) since prior to February 14, 1994, has
      been subject to the requirements of Section 12 of the Exchange Act and has
      filed all the material required to be filed pursuant to Sections 13 and 14
      of the Exchange Act, and (B) since prior to February 14, 1996, has filed
      in a timely manner all reports required to be filed under Sections 13 and
      14 of the Exchange Act, and has not used Rule 12b-25(b) under the Exchange
      Act.

                  (iv) Neither the Company nor any Subsidiary has, since
      December 31, 1996, (A) failed to pay any dividend or sinking fund
      installment on preferred stock, or (B) defaulted (I) on any installment or
      installments on indebtedness for borrowed money, or (II) on any rental on
      one or more long term leases.

                  (v) The aggregate market value of the Company's voting stock
      held by non-affiliates of the Company is $100 million or more and the
      Company had a trading volume of such stock of 3,000,000 shares or more
      during the 12 month period ended July 22, 1997.

      7. Indemnification and Contribution. (a) The Company and the Operating
Partnership, jointly and severally, agree to indemnify and hold harmless each
Underwriter, the directors, officers, employees and agents of each Underwriter,
and each person, if any, who controls any Underwriter within the meaning of
Section 15 of the Act or Section 20 of the Exchange Act from and against any and
all losses, claims, damages, liabilities and expenses (including reasonable
costs of investigation) arising out of or based upon any untrue statement or


                                      -15-
<PAGE>

alleged untrue statement of a material fact contained in any Prepricing
Prospectus or in the Registration Statement or the Prospectus or in any
amendment or supplement thereto, or arising out of or based upon any omission or
alleged omission to state therein a material fact required to be stated therein
or necessary to make the statements therein not misleading, except insofar as
such losses, claims, damages, liabilities or expenses arise out of or are based
upon any untrue statement or omission or alleged untrue statement or omission
which has been made therein or omitted therefrom in reliance upon and in
conformity with the information relating to such Underwriter furnished in
writing to the Company by or on behalf of any Underwriter through you expressly
for use in connection therewith (which information is described in its entirety
in Section 13 below); provided, however, that the indemnification contained in
this paragraph (a) with respect to any Prepricing Prospectus shall not inure to
the benefit of any Underwriter (or to the benefit of any person controlling such
Underwriter) on account of any such loss, claim, damage, liability or expense
arising from the sale of the Shares by such Underwriter to any person if a copy
of the Prospectus shall not have been delivered or sent to such person within
the time required by the Act and the regulations thereunder, and the untrue
statement or alleged untrue statement or omission or alleged omission of a
material fact contained in such Prepricing Prospectus was corrected in the
Prospectus, provided that the Company has delivered the Prospectus to the
several Underwriters in requisite quantity on a timely basis to permit such
delivery or sending within the time required by the Act. The foregoing indemnity
agreement shall be in addition to any liability which the Company may otherwise
have.

      (b) If any action, suit or proceeding shall be brought against any
Underwriter or any person controlling any Underwriter in respect of which
indemnity may be sought against the Company or the Operating Partnership, such
Underwriter or such controlling person shall promptly notify the Company or the
Operating Partnership, and the Company or the Operating Partnership shall assume
the defense thereof, including the employment of counsel and payment of all fees
and expenses. Such Underwriter or any such controlling person shall have the
right to employ separate counsel in any such action, suit or proceeding and to
participate in the defense thereof, but the fees and expenses of such counsel
shall be at the expense of such Underwriter or such controlling person unless
(i) the Company and the Operating Partnership have agreed in writing to pay such
fees and expenses, (ii) the Company and the Operating Partnership have failed to
assume the defense and employ counsel, or (iii) the named parties to any such
action, suit or proceeding (including any impleaded parties) include both such
Underwriter or such controlling person and the Company or the Operating
Partnership and such Underwriter or such controlling person shall have been
advised by its counsel that representation of such indemnified party and the
Company or the Operating Partnership by the same counsel would be inappropriate
under applicable standards of professional conduct (whether or not such
representation by the same counsel has been proposed) due to actual or potential
differing interests between them (in which case the Company and the Operating
Partnership shall not have the right to assume the defense of such action, suit
or proceeding on behalf of such Underwriter or such controlling person). It is
understood, however, that the Company shall, in connection with any one such
action, suit or proceeding or separate but substantially similar or related
actions, suits or proceedings in the same jurisdiction arising out of the same
general allegations or circumstances, be liable for the reasonable fees and
expenses of only one separate firm of attorneys (in addition to any local
counsel) at any time for all such Underwriters and controlling persons not
having actual or potential differing interests with you or among themselves,
which firm shall be designated in writing by Smith Barney Inc., and that all
such fees and expenses shall be reimbursed as they are


                                      -16-
<PAGE>

incurred. The Company and the Operating Partnership shall not be liable for any
settlement of any such action, suit or proceeding effected without its written
consent, but if settled with such written consent, or if there shall be a final
judgment for the plaintiff in any such action, suit or proceeding, the Company
and the Operating Partnership agree to indemnify and hold harmless any
Underwriter, to the extent provided in the preceding paragraph, and any such
controlling person from and against any loss, claim, damage, liability or
expense by reason of such settlement or judgment.

      (c) Each Underwriter agrees, severally and not jointly, to indemnify and
hold harmless the Company, its trustees and officers who sign the Registration
Statement, and any person who controls the Company within the meaning of Section
15 of the Act or Section 20 of the Exchange Act, to the same extent as the
foregoing indemnity from the Company and the Operating Partnership to each
Underwriter, but only with respect to losses, claims, damages, liabilities and
expenses arising out of or based on information relating to such Underwriter
furnished in writing by or on behalf of such Underwriter through you expressly
for use in the Registration Statement, the Prospectus or any Prepricing
Prospectus or any amendment or supplement thereto. If any action, suit or
proceeding shall be brought against the Company, any of its directors or
officers, or any such controlling person based on the Registration Statement,
the Prospectus or any Prepricing Prospectus, or any amendment or supplement
thereto, and in respect of which indemnity may be sought against any Underwriter
pursuant to this paragraph (c), such Underwriter shall have the rights and
duties given to the Company and the Operating Partnership by paragraph (b) above
(except that if the Company or the Operating Partnership shall have assumed the
defense thereof such Underwriter shall not be required to do so, but may employ
separate counsel therein and participate in the defense thereof, but the fees
and expenses of such counsel shall be at such Underwriter's expense), and the
Company, its trustees and officers, and any such controlling person shall have
the rights and duties given to the Underwriters by paragraph (b) above. The
foregoing indemnity agreement shall be in addition to any liability which the
Underwriters may otherwise have.

      (d) If the indemnification provided for in this Section 7 is unavailable
to an indemnified party under paragraphs (a) or (c) hereof in respect of any
losses, claims, damages, liabilities or expenses referred to therein, then an
indemnifying party, in lieu of indemnifying such indemnified party, shall
contribute to the amount paid or payable by such indemnified party as a result
of such losses, claims, damages, liabilities or expenses (i) in such proportion
as is appropriate to reflect the relative benefits received by the Company and
the Operating Partnership, on the one hand, and the Underwriters, on the other
hand, from the offering of the Shares, or (ii) if the allocation provided by
clause (i) above is not permitted by applicable law, in such proportion as is
appropriate to reflect not only the relative benefits referred to in clause (i)
above but also the relative fault of the Company and the Operating Partnership,
on the one hand, and the Underwriters, on the other, in connection with the
statements or omissions that resulted in such losses, claims, damages,
liabilities or expenses, as well as any other relevant equitable considerations.
The relative benefits received by the Company and the Operating Partnership, on
the one hand, and the Underwriters, on the other, shall be deemed to be in the
same proportion as the total net proceeds from the offering (before deducting
expenses) received by the Company and the Operating Partnership bear to the
total underwriting discounts and commissions received by the Underwriters, in
each case as set forth in the table on the cover page of the Prospectus. The
relative fault of the Company on the one hand and the Underwriters on the other
hand shall


                                      -17-
<PAGE>

be determined by reference to, among other things, whether the untrue or alleged
untrue statement of a material fact or the omission or alleged omission to state
a material fact relates to information supplied by the Company on the one hand
or by the Underwriters on the other hand and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent such
statement or omission.

      (e) The Company, the Operating Partnership and the Underwriters agree that
it would not be just and equitable if contribution pursuant to this Section 7
were determined by a pro rata allocation (even if the Underwriters were treated
as one entity for such purpose) or by any other method of allocation that does
not take account of the equitable considerations referred to in paragraph (d)
above. The amount paid or payable by an indemnified party as a result of the
losses, claims, damages, liabilities and expenses referred to in paragraph (d)
above shall be deemed to include, subject to the limitations set forth above,
any legal or other expenses reasonably incurred by such indemnified party in
connection with investigating any claim or defending any such action, suit or
proceeding. Notwithstanding the provisions of this Section 7, no Underwriter
shall be required to contribute any amount in excess of the amount by which the
total price of the Shares underwritten by it and distributed to the public
exceeds the amount of any damages which such Underwriter has otherwise been
required to pay by reason of such untrue or alleged untrue statement or omission
or alleged omission. No person guilty of fraudulent misrepresentation (within
the meaning of Section 11(f) of the Act) shall be entitled to contribution from
any person who was not guilty of such fraudulent misrepresentation. The
Underwriters' obligations to contribute pursuant to this Section 7 are several
in proportion to the respective numbers of Firm Shares set forth opposite their
names in Schedule I hereto (or such numbers of Firm Shares increased as set
forth in Section 11 hereof) and not joint.

      (f) No indemnifying party shall, without the prior written consent of the
indemnified party, effect any settlement of any pending or threatened action,
suit or proceeding in respect of which any indemnified party is or could have
been a party and indemnity could have been sought hereunder by such indemnified
party, unless such settlement includes an unconditional release of such
indemnified party from all liability on claims that are the subject matter of
such action, suit or proceeding.

      (g) Any losses, claims, damages, liabilities or expenses for which an
indemnified party is entitled to indemnification or contribution under this
Section 7 shall be paid by the indemnifying party to the indemnified party as
such losses, claims, damages, liabilities or expenses are incurred. The
indemnity and contribution agreements contained in this Section 7 and the
representations and warranties of the Company and the Operating Partnership set
forth in this Agreement shall remain operative and in full force and effect,
regardless of (i) any investigation made by or on behalf of any Underwriter or
any person controlling any Underwriter, the Company and its trustees or
officers, the Operating Partnership and its officers, or any person controlling
the Company or the Operating Partnership, (ii) acceptance of any Shares and
payment therefor hereunder, and (iii) any termination of this Agreement. A
successor to any Underwriter or any person controlling any Underwriter, or to
the Company and its trustees or officers, the Operating Partnership and its
officers, or any person controlling the Company or the Operating Partnership,
shall be entitled to the benefits of the indemnity, contribution, and
reimbursement agreements contained in this Section 7.


                                      -18-
<PAGE>

      8. Conditions of Underwriters' Obligations. The several obligations of the
Underwriters to purchase the Firm Shares hereunder are subject to the following
conditions:

            (a) If, at the time this Agreement is executed and delivered, it is
necessary for the registration statement or a post-effective amendment thereto
to be declared effective before the offering of the Shares may commence, the
registration statement or such post-effective amendment shall have become
effective not later than 5:30 P.M., New York City time, on the date hereof, or
at such later date and time as shall be consented to in writing by you, and all
filings, if any, required by Rules 424 and 430A under the Act shall have been
timely made; no stop order suspending the effectiveness of the registration
statement shall have been issued and no proceeding for that purpose shall have
been instituted or, to the knowledge of the Company or any Underwriter,
threatened by the Commission, and any request of the Commission for additional
information (to be included in the Registration Statement or the Prospectus or
otherwise) shall have been complied with to your satisfaction.

            (b) Subsequent to the effective date of this Agreement, there shall
not have occurred (i) any change, or any development involving a prospective
change, in or affecting the condition (financial or other), business, prospects,
properties, net worth, or results of operations of the Company or the
Subsidiaries not contemplated by the Prospectus, which in your opinion would
materially, adversely affect the market for the Shares, or (ii) any event or
development relating to or involving the Company or any officer or trustee of
the Company or the Operating Partnership which makes any statement made in the
Prospectus untrue or which, in the opinion of the Company and its counsel or the
Underwriters and their counsel, requires the making of any addition to or change
in the Prospectus in order to state a material fact required by the Act or any
other law to be stated therein or necessary in order to make the statements
therein, in light of the circumstances in which they were made, not misleading,
if amending or supplementing the Prospectus to reflect such event or development
would, in your opinion, materially, adversely affect the market for the Shares.

            (c) You shall have received on the Closing Date, the opinion of
Pepper, Hamilton & Scheetz LLP, counsel for the Company, the Operating
Partnership and the other Subsidiaries, dated the Closing Date and addressed to
you, in the form set forth on Exhibit 8(c) attached hereto.

            In rendering their opinion as aforesaid, such counsel may rely upon
an opinion or opinions, each dated the Closing Date, of other counsel retained
by them or the Company as to laws of any jurisdiction other than the United
States, the State of New York, the Commonwealth of Pennsylvania and the State of
Delaware, provided that (1) each such local counsel is reasonably acceptable to
you, (2) such reliance is expressly authorized by each opinion so relied upon
and a copy of each such opinion is delivered to you and is, in form and
substance, satisfactory to you and your counsel, and (3) such counsel shall
state in their opinion that they believe that they and the Underwriters are
justified in relying thereon.

            (d) You shall have received on the Closing Date an opinion of Arthur
Andersen LLP, special tax advisor to the Company, satisfactory in form and
substance to you, to the effect that (i) the descriptions of the Federal income
tax conclusions contained in the Prospectus under the caption "Federal Income
Tax Considerations" are correct in all material respects, and the


                                      -19-
<PAGE>

discussion contained therein fairly summarizes the Federal income tax
considerations that may be material to a holder of the common shares; (ii)
assuming the Company is operated in accordance with the assumptions and
representations of management regarding its activities and intended activities,
the Company will continue to qualify as a REIT under the Code; and (iii) the
Operating Partnership and the Title Holding Partnerships will be treated for
Federal income tax purposes as partnerships and not as associations taxable as
corporations or as publicly-traded partnerships.

            (e) You shall have received on the Closing Date, an opinion of
Arthur Andersen LLP, special tax advisor to the Company, dated the Closing Date
and addressed to you, satisfactory in form and substance to you, to the effect
that the Company will not be considered to own more than ten percent of the
outstanding voting securities of Brandywine Realty Services Corp. at the close
of the years ended December 31, 1996 and December 31, 1997.

            (f) You shall have received on the Closing Date an opinion of Battle
Fowler LLP, counsel for the Underwriters, dated the Closing Date and addressed
to you, with respect to the Registration Statement, the Prospectus and this
Agreement and such other related matters as you may request.

            (g) You shall have received comfort letters, including, but not
limited to, certain agreed upon procedures, addressed to you and dated the date
hereof and the Closing Date from Arthur Andersen LLP and Zelenkofske Axelrod &
Company Ltd., independent public accountants, substantially in the forms
heretofore approved by you. The comfort letters dated the Closing Date shall
include language in scope and substance substantially as set forth on Exhibit
8(g).

            (h) (i) No stop order suspending the effectiveness of the
Registration Statement shall have been issued and no proceedings for that
purpose shall have been taken or, to the knowledge of the Company or the
Underwriters, shall be contemplated by the Commission at or prior to the Closing
Date; (ii) there shall not have been any change in the beneficial interest of
the Company nor any material increase in the short-term or long-term debt of the
Company (other than in the ordinary course of business) from that set forth or
contemplated in the Registration Statement or the Prospectus (or any amendment
or supplement thereto); (iii) there shall not have been, since the respective
dates as of which information is given in the Registration Statement and the
Prospectus (or any amendment or supplement thereto), except as may otherwise be
stated in the Registration Statement and Prospectus (or any amendment or
supplement thereto), any material adverse change in the condition (financial or
other), business, prospects, properties, net worth or results of operations of
the Properties or the Company and the Subsidiaries taken as a whole; (iv) the
Company and the Subsidiaries shall not have any liabilities or obligations,
direct or contingent (whether or not in the ordinary course of business), that
are material to the Company and the Subsidiaries, taken as a whole, other than
those reflected in the Registration Statement or the Prospectus (or any
amendment or supplement thereto); and (v) all the representations and warranties
of the Company and the Operating Partnership contained in this Agreement shall
be true and correct on and as of the date hereof and on and as of the Closing
Date as if made on and as of the Closing Date, and you shall have received a
certificate, dated the Closing Date and signed by the chief executive officer
and the chief financial officer of the Company (or such other officers as are
acceptable to you), to the effect set forth in this Section 8(h) and in Section
8(i) hereof.


                                      -20-
<PAGE>

            (i) The Company shall not have failed at or prior to the Closing
Date to have performed or complied with any of its agreements herein contained
and required to be performed or complied with by it hereunder at or prior to the
Closing Date.

            (j) The Shares shall have been listed or approved for listing upon
notice of issuance on the American Stock Exchange.

            (k) The Company and the Operating Partnership shall have furnished
or caused to be furnished to you such further certificates and documents as you
shall have reasonably requested.

      All such opinions, certificates, letters and other documents will be in
compliance with the provisions hereof only if they are satisfactory in form and
substance to you and your counsel.

      Any certificate or document signed by any officer of the Company and the
Operating Partnership and delivered to you, or to counsel for the Underwriters,
shall be deemed a representation and warranty by the Company or the Operating
Partnership, as applicable, to each Underwriter as to the statements made
therein.

      The several obligations of the Underwriters to purchase Additional Shares
hereunder are subject to the satisfaction on and as of any Option Closing Date
of the conditions set forth in this Section 8, except that, if any Option
Closing Date is other than the Closing Date, the certificates, opinions and
letters referred to in paragraphs (c) through (h) shall be dated the Option
Closing Date in question and the opinions called for by paragraphs (c), (d), (e)
and (f) shall be revised to reflect the sale of Additional Shares.

      9. Expenses. The Company agrees to pay the following costs and expenses
and all other costs and expenses incident to the performance by it of its
obligations hereunder: (i) the preparation, printing or reproduction, and filing
with the Commission of the Registration Statement (including financial
statements and exhibits thereto), each Prepricing Prospectus, the Prospectus,
and each amendment or supplement to any of them; (ii) the printing (or
reproduction) and delivery (including postage, air freight charges and charges
for counting and packaging) of such copies of the Registration Statement, each
Prepricing Prospectus, the Prospectus, and all amendments or supplements to any
of them as may be reasonably requested for use in connection with the offering
and sale of the Shares; (iii) the preparation, printing, authentication,
issuance and delivery of certificates for the Shares, including any stamp taxes
in connection with the original issuance and sale of the Shares; (iv) if
required, the printing (or reproduction) and delivery of this Agreement, the
preliminary and supplemental Blue Sky Memoranda and all other agreements or
documents printed (or reproduced) and delivered in connection with the offering
of the Shares; (v) the listing of the Shares on the American Stock Exchange;
(vi) if required, the registration or qualification of the Shares for offer and
sale under the securities or Blue Sky laws of the several states as provided in
Section 5(g) hereof (including the reasonable fees, expenses and disbursements
of counsel for the Underwriters relating to the preparation, printing or
reproduction, and delivery of the preliminary and supplemental Blue Sky
Memoranda and such registration and qualification); (vii) if required, the
filing fees and the fees and expenses of counsel for the Underwriters in
connection with any filings required to be made with the National Association of
Securities Dealers, Inc.; (viii) the transportation and other expenses incurred
by


                                      -21-
<PAGE>

or on behalf of Company representatives in connection with presentations to
prospective purchasers of the Shares; and (ix) the fees and expenses of the
Company's accountants and the fees and expenses of counsel (including local and
special counsel) for the Company.

      10. Effective Date of Agreement. This Agreement shall become effective:
(i) upon the execution and delivery hereof by the parties hereto; or (ii) if, at
the time this Agreement is executed and delivered, it is necessary for the
Registration Statement or a post-effective amendment thereto to be declared
effective before the offering of the Shares may commence, when notification of
the effectiveness of the Registration Statement or such post-effective amendment
has been released by the Commission. Until such time as this Agreement shall
have become effective, it may be terminated by the Company, by notifying you, or
by you, by notifying the Company.

      11. Default of Underwriters. If any one or more of the Underwriters shall
fail or refuse to purchase Firm Shares which it or they are obligated to
purchase hereunder on the Closing Date, and the aggregate number of Firm Shares
which such defaulting Underwriter or Underwriters are obligated but fail or
refuse to purchase is not more than one-tenth of the aggregate number of Firm
Shares which the Underwriters are obligated to purchase on the Closing Date,
each non-defaulting Underwriter shall be obligated, severally, in the proportion
which the number of Firm Shares set forth opposite its name in Schedule I hereto
bears to the aggregate number of Firm Shares set forth opposite the names of all
non-defaulting Underwriters or in such other proportion as you may specify in
accordance with Section 20 of the Master Agreement Among Underwriters of Smith
Barney Inc., to purchase the Firm Shares which such defaulting Underwriter or
Underwriters are obligated, but fail or refuse, to purchase. If any one or more
of the Underwriters shall fail or refuse to purchase Firm Shares which it or
they are obligated to purchase on the Closing Date and the aggregate number of
Firm Shares with respect to which such default occurs is more than one-tenth of
the aggregate number of Firm Shares which the Underwriters are obligated to
purchase on the Closing Date and arrangements satisfactory to you and the
Company for the purchase of such Firm Shares by one or more non-defaulting
Underwriters or other party or parties approved by you and the Company are not
made within 36 hours after such default, this Agreement will terminate without
liability on the part of any non-defaulting Underwriter or the Company. In any
such case which does not result in termination of this Agreement, either you or
the Company shall have the right to postpone the Closing Date, but in no event
for longer than seven days, in order that the required changes, if any, in the
Registration Statement and the Prospectus or any other documents or arrangements
may be effected. Any action taken under this paragraph shall not relieve any
defaulting Underwriter from liability in respect of any such default of any such
Underwriter under this Agreement. The term "Underwriter" as used in this
Agreement includes, for all purposes of this Agreement, any party not listed in
Schedule I hereto who, with your approval and the approval of the Company,
purchases Shares which a defaulting Underwriter is obligated, but fails or
refuses, to purchase.

      Any notice under this Section 11 may be given by telegram, telecopy or
telephone but shall be subsequently confirmed by letter.

      12. Termination of Agreement. This Agreement shall be subject to
termination in your absolute discretion, without liability on the part of any
Underwriter to the Company, by notice


                                      -22-
<PAGE>

to the Company, if prior to the Closing Date or any Option Closing Date (if
different from the Closing Date and then only as to the Additional Shares), as
the case may be, (i) trading in securities generally on the New York Stock
Exchange, the American Stock Exchange or the Nasdaq National Market shall have
been suspended or materially limited, (ii) a general moratorium on commercial
banking activities in New York or Pennsylvania shall have been declared by
either federal or state authorities, or (iii) there shall have occurred any
outbreak or escalation of hostilities or other international or domestic
calamity, crisis or change in political, financial or economic conditions, the
effect of which on the financial markets of the United States is such as to make
it, in your judgment, impracticable or inadvisable to commence or continue the
offering of the Shares at the offering price to the public set forth on the
cover page of the Prospectus or to enforce contracts for the resale of the
Shares by the Underwriters. Notice of such termination may be given to the
Company by telegram, telecopy or telephone and shall be subsequently confirmed
by letter.

      13. Information Furnished by the Underwriters. The Company and the
Operating Partnership acknowledge and agree that the statements set forth in the
last paragraph on the cover page, the stabilization legend on the inside cover
page, the list of Underwriters and their respective allotments appearing under
the caption "Underwriting" in the Prospectus and the statements in the first and
third paragraphs under the caption "Underwriting" in any Prepricing Prospectus
and in the Prospectus, constitute the only information furnished by or on behalf
of the Underwriters as such information is referred to in Sections 6(b) and 7
hereof.

      14. Miscellaneous. Except as otherwise provided in Sections 6, 11 and 12
hereof, notice given pursuant to any provision of this Agreement shall be in
writing and shall be delivered (i) if to the Company or the Operating
Partnership, at the office of the Company at 16 Campus Boulevard, Newtown
Square, Pennsylvania 19073, Attention: Gerard H. Sweeney, President and Chief
Executive Officer; or (ii) if to you, in care of Smith Barney Inc., 388
Greenwich Street, New York, New York 10013, Attention: Manager, Investment
Banking Division.

      This Agreement has been and is made solely for the benefit of the several
Underwriters, the Company, its trustees and officers, the Operating Partnership
and the other controlling persons referred to in Section 7 hereof and their
respective successors and assigns, to the extent provided herein, and no other
person shall acquire or have any right under or by virtue of this Agreement.
Neither the term "successor" nor the term "successors and assigns" as used in
this Agreement shall include a purchaser from any Underwriter of any of the
Shares in his status as such purchaser.

      15. Applicable Law; Counterparts. This Agreement shall be governed by and
construed in accordance with the laws of the State of New York applicable to
contracts made and to be performed within the State of New York.

      This Agreement may be signed in various counterparts which together
constitute one and the same instrument. If signed in counterparts, this
Agreement shall not become effective unless at least one counterpart hereof
shall have been executed and delivered on behalf of each party hereto.


                                      -23-
<PAGE>

      Please confirm that the foregoing correctly sets forth the agreement among
the Company, the Operating Partnership and the several Underwriters.


                               Very truly yours,


                               BRANDYWINE REALTY TRUST


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


                               BRANDYWINE OPERATING PARTNERSHIP, L.P.


                               By:  Brandywine Realty Trust,
                                    its general partner


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


Confirmed as of the date first above mentioned.

SMITH BARNEY INC.
DONALDSON, LUFKIN & JENRETTE
    SECURITIES CORPORATION
LEGG MASON WOOD WALKER, INCORPORATED
MERRILL LYNCH, PIERCE, FENNER & SMITH
    INCORPORATED


By:  SMITH BARNEY INC.


     By:  /S/ Mark R. Patterson
          -----------------------------
          Mark R. Patterson
          Managing Director
<PAGE>

                                   SCHEDULE I

                             BRANDYWINE REALTY TRUST

                                                          Number
                                                          of Firm
Underwriter                                               Shares
- -----------                                               ------

Smith Barney Inc.......................................  2,500,000
Donaldson, Lufkin & Jenrette Securities Corporation ...  2,500,000
Legg Mason Wood Walker, Incorporated...................  2,500,000
Merrill Lynch, Pierce, Fenner & Smith
     Incorporated......................................  2,500,000

     Total............................................. 10,000,000
                                                        ==========
<PAGE>

                                  Schedule 6(d)

                              Transaction Documents

         Identified herein are the documents that constitute the "Transaction
Documents" referenced in this Underwriting Agreement.

1.   (a) Agreement of Sale dated January 20, 1997 between BRT ("Purchaser")
         and 1120 Associates Limited Partnership, a Delaware limited partnership
         ("1120"), MLCP Associates Limited Partnership, a Delaware limited
         partnership ("MLCP") and Executive Court Associates Limited
         Partnership, a Delaware limited partnership ("ECA") (collectively,
         1120, MLCP and ECA are referred to as "Seller"): (i) 1120 Executive
         Plaza, Mount Laurel Township, Burlington County, New Jersey (Seller -
         1120); (ii) Mt. Laurel Corporate Park, 1000 Howard Boulevard, Mount
         Laurel Township, Burlington County, New Jersey (Seller - MLCP); and
         (iii) Executive Court, Two, Four A and Four B Eves Drive, Evesham
         Township, Burlington County, New Jersey (Seller - ECA).

     (b) Pursuant to an Assignment and Assumption Agreement effective as of
         January 20, 1997, Purchaser assigned its interest under the Agreement
         of Sale to Brandywine Operating Partnership, L.P., a Delaware limited
         partnership ("BOP").

2.   (a) Agreement of Sale dated February 14, 1997 between BRT ("Purchaser")
         and Hough/Loew Construction, Inc., a Pennsylvania corporation
         ("Seller"): 1336 Enterprise Drive, Goshen Corporate Park, East Goshen
         Township, Chester County, Pennsylvania.

     (b) Pursuant to an Assignment of Agreement of Sale dated as of March 6,
         1997, Purchaser assigned its interest under the Agreement of Sale to
         BOP.

3.   (a) Agreement of Sale dated as of February 21, 1997 between BRT
         ("Purchaser") and Mellon Bank, N.A., not personally, but as Trustee of
         the Westinghouse Electric Corporation Master Trust Fund ("Seller"): 201
         and 221 King Manor Drive, King of Prussia, Upper Merion Township,
         Montgomery County, Pennsylvania. The Agreement of Sale was amended by a
         First Amendment to Agreement of Sale dated as of April 3, 1997 by and
         among Purchaser, BOP and Seller and by letter agreements dated March 6,
         1997, March 13, 1997, March 18, 1997, March 25, 1997, March 31, 1997
         and April 1, 1997.

     (b) Pursuant to an Assignment of Agreement of Sale dated as of March 4,
         1997, Purchaser assigned its interest under the Agreement of Sale to
         BOP.

4.   (a) Agreement of Sale dated February 21, 1997 by and between BRT
         ("Purchaser") and Radnor-Camco Partnership, a New Jersey general
         partnership ("Seller"): (i) Plaza 1000 Building; (ii) the Promenade
         Commercial Space (2 office properties); (iii) the Piazza Commercial
         Space (4 office properties), (iv) the Undeveloped Land, and (v) the
         Main Street Common Facilities (each of the foregoing as defined in the
<PAGE>

         Agreement of Sale), the foregoing properties are located at the
         intersection of Kresson and Evesham Roads, Voorhees, Camden County, New
         Jersey. The Agreement of Sale was amended by an Addendum to Agreement
         of Sale dated as of March 4, 1997 by and between Seller and
         Brandywine-Main Street, LLC, a Delaware limited liability company,
         assignee of BRT.

     (b) Pursuant to an Assignment and Assumption Agreement effective as of
         February 22, 1997, Purchaser assigned its interest under the Agreement
         of Sale to Brandywine-Main Street, LLC, a Delaware limited liability
         company.

5.   (a) Agreement of Purchase and Sale dated as of April 7, 1997 by and
         between BRT ("Purchaser") and Advent Realty Limited Partnership, a
         Delaware limited partnership ("Advent") and Advent Realty Limited
         Partnership II, a Delaware limited partnership ("Advent II")
         (collectively, Advent and Advent II are referred to as "Seller"): (i)
         Oxford Corporate Center, 2000, 2005 and 2010 Cabot Boulevard,
         Langhorne, Bucks County, Pennsylvania (Seller - Advent); (ii)
         Springhouse Corporate Center, 321 and 323 Norristown Road, Ambler,
         Lower Gwynedd Township, Montgomery County, Pennsylvania (Seller -
         Advent); (iii) Greentree Commons , 9000 West Lincoln Drive (9001, 9002,
         9003 and 9004), Marlton, Evesham Township, Burlington County, New
         Jersey (Seller - Advent); and (iv) Highland Business Center, 300, 400,
         500 and 600 Highland Drive, Westampton Township, Burlington County, New
         Jersey (Seller - Advent II). The Agreement of Purchase and Sale was
         amended by (A) a First Amendment to Agreement of Purchase and Sale
         dated as of May 14, 1997 by and between Seller and Purchaser; and (B) a
         Second Amendment to Agreement for Purchase and Sale dated as of May 21,
         1997 by and among Advent II, BRT and BOP.

     (b) Pursuant to an Assignment of Agreement of Purchase and Sale dated as of
         May 21, 1997, Purchaser assigned its interest under the Agreement of
         Purchase and Sale to BOP.

6.       Agreement of Sale dated April 8, 1997 between BOP ("Purchaser") and
         Avenir II Corporation, a Pennsylvania corporation ("Seller"): 748 and
         855 Springdale Drive, Whitelands Business Park, Exton, West Whiteland
         Township, Chester County, Pennsylvania.

7.   (a) Agreement of Sale dated as of April 15, 1997 by and between BRT
         ("Purchaser") and EDB Property Partners, L.P. I, a Delaware limited
         partnership ("Seller"): (i) 7000 Geerdes Boulevard, King of Prussia,
         Upper Merion Township, Montgomery County, Pennsylvania; and (ii) (A)
         2000 Midlantic Drive; (B) 4000 Midlantic Drive; (C) 9000 Midlantic
         Drive; (D) 10000 Midlantic Drive; and (E) 15000 Midlantic Drive, Mount
         Laurel Township, Burlington County, New Jersey. The Agreement of Sale
         was amended by a Modification Agreement dated as of May 15, 1997 by and
         between Seller and Purchaser.

     (b) Pursuant to an Assignment of Agreement of Sale dated as of May 30,
         1997, Purchaser assigned its interest under the Agreement of Sale to
         BOP.
<PAGE>

8.   (a) Agreement of Sale dated April 18, 1997 by and between BRT
         ("Purchaser") and LAKN Marlton Associates, L.P., a New Jersey limited
         partnership ("Seller"): Five Eves Drive, Evesham Corporate Center,
         Marlton Evesham Township, Burlington County, New Jersey.

     (b) Pursuant to an Assignment and Assumption Agreement dated as of April
         18, 1997, Purchaser assigned its interest under the Agreement of Sale
         to BOP.

9.   (a) Agreement of Sale dated April 18, 1997 by and between BRT
         ("Purchaser") and Ira M. Lubert, individually and Karen S. Lubert,
         individually ("Seller") and an Agreement of Sale dated April 18, 1997
         by and between Purchaser and Howard E. Needleman, individually
         ("Seller"):1000/2000 West Lincoln Drive (1001; 1002; 1003; 2001; 2002;
         and 2003), Marlton, Evesham Township, Burlington County, New Jersey
         (Sellers: 1000 - Luberts and 2000 Needleman).

     (b) Pursuant to Assignment and Assumption Agreements each dated as of April
         18, 1997, Purchaser assigned its interest under each Agreement of Sale
         to BOP.

10.  (a) Agreement of Sale dated April 18, 1997 by and between BRT
         ("Purchaser") and 3001-2-3 Greentree Associates, L.P., a New Jersey
         limited partnership ("Seller"): 3000 West Lincoln Drive (3001; 3002;
         and 3003), Marlton, Evesham Township, Burlington County, New Jersey.

     (b) Pursuant to an Assignment and Assumption Agreement dated as of April
         18, 1997, Purchaser assigned its interest under the Agreement of Sale
         to BOP.

11.  (a) Agreement of Sale dated April 18, 1997 by and between BRT
         ("Purchaser") and 4000-5000 Greentree Executive Campus Associates,
         L.P., a New Jersey limited partnership ("Seller"): 4000/5000 West
         Lincoln Drive (4001; 4002; 4003; 5001; and 5002), Marlton, Evesham
         Township, Burlington County, New Jersey.

     (b) Pursuant to an Assignment and Assumption Agreement dated as of April
         18, 1997, Purchaser assigned its interest under the Agreement of Sale
         to BOP.

12.  (a) Sale Agreement dated May 20, 1997 by and between BRT ("Purchaser")
         and Metropolitan Life Insurance Company, a New York corporation
         ("Seller"): 1974 Sproul Road, Broomall, Marple Township, Delaware
         County, Pennsylvania.

     (b) Pursuant to an Assignment and Assumption Agreement dated as of June 16,
         1997, Purchaser assigned its interest under the Agreement of Sale to
         BOP.

13.      Agreement of Sale dated June 26, 1997 by and between BRT ("Purchaser")
         and Salient 3 Communications, Inc. ("Seller"): 100 Gundy, 200 Gundy,
         100 Davis, 300 Gundy and 100 Kachel Boulevard (Green Hills Corporate
         Center), Cumru and Robeson Townships, Berks County, Pennsylvania.

14.      Sale Agreement by and between Berwyn Development Associates ("Seller")
         and BRT ("Purchaser"): Berwyn Park properties, Berwyn, Chester County,
         Pennsylvania.
<PAGE>

                                  SCHEDULE 6(e)

                           Subsidiaries of the Company

Brandywine Operating Partnership, a Delaware limited partnership

Fifteen Horsham, L.P., a Pennsylvania limited partnership

C/N Oaklands Limited Partnership I, a Pennsylvania limited partnership

Newtech IV Limited Partnership, a Pennsylvania limited partnership

Newtech III Limited Partnership, a Pennsylvania limited partnership

LC/N Keith Valley Limited Partnership I, a Pennsylvania limited partnership

LC/N Horsham Limited Partnership, a Pennsylvania limited partnership

Nichols Landsdale Limited Partnership III, a Pennsylvania limited partnership

Witmer Operating Partnership I, L.P., a Delaware limited partnership

C/N Leedom Limited Partnership II, a Pennsylvania limited partnership

C/N Oaklands Limited Partnership III, a Pennsylvania limited partnership

Iron Run Limited Partnership V, a Pennsylvania limited partnership

C/N Iron Run Limited Partnership III, a Pennsylvania limited partnership

Brandywine Realty Partners, a Pennsylvania general partnership

Brandywine Holdings I, Inc., a Pennsylvania corporation

Brandywine Holdings II, Inc., a Pennsylvania corporation

Brandywine Holdings III, Inc., a Pennsylvania corporation

Brandywine Realty Services Corporation, a Pennsylvania corporation

Brandywine Acquisitions, LLC

Brandywine - Main Street, LLC
<PAGE>

                                  SCHEDULE 6(g)

                       Ownership Interests in Subsidiaries

                                  See Attached


<PAGE>
                                                                    Exhibit 10.1

                                 FIRST AMENDMENT
                                       TO
                           REVOLVING CREDIT AGREEMENT
                                       AND
                         OTHER CREDIT FACILITY DOCUMENTS

            FIRST AMENDMENT TO REVOLVING CREDIT AGREEMENT AND OTHER CREDIT
FACILITY DOCUMENTS (this "Amendment") entered into as of the 15th day of July,
1997, among NATIONSBANK, N.A., acting in its capacity as administrative and
documentation agent for Co-Lenders (NationsBank, N.A., acting in its capacity as
administrative and documentation agent for Co-Lenders or any other entity which
is designated as administrative and documentation agent in accordance with the
provisions of the Co-Lenders Agreement being hereinafter referred to as
"Agent"); NATIONSBANK, N.A., ("NationsBank"), a national banking association
having an office at 8300 Greensboro Drive, McLean, Virginia, acting in its
individual capacity; SMITH BARNEY MORTGAGE CAPITAL GROUP, INC. ("Smith Barney"),
a Delaware corporation having an office at 390 Greenwich Street, New York, New
York; THE FIRST NATIONAL BANK OF CHICAGO ("First Chicago"), a national banking
association having an office at One First National Plaza, Chicago, Illinois;
MELLON BANK, N.A. ("Mellon"), a national banking association having an office at
1735 Market Street, Philadelphia, Pennsylvania; PNC BANK, NATIONAL ASSOCIATION
("PNC"), a national banking association having an office at 1600 Market Street,
Philadelphia, Pennsylvania; SIGNET BANK ("Signet"), a state banking association
organized under the laws of the Commonwealth of Virginia having an office at
7799 
<PAGE>

Leesburg Pike, 4th Floor, Falls Church, Virginia; and SUMMIT BANK, N.A.
("Summit"), a state banking association organized under the laws of the State of
New Jersey having an office at 1800 Chapel Avenue West, Cherry Hill, New Jersey
(NationsBank, Smith Barney, First Chicago, Mellon, PNC, Signet and Summit are
hereinafter collectively referred to as the "Co-Lenders"); BRANDYWINE REALTY
TRUST ("BRT"), a Maryland real estate investment trust having an office at
Newtown Square Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
Pennsylvania; BRANDYWINE OPERATING PARTNERSHIP, L.P. ("BOP"), a Delaware limited
partnership having an office at Newtown Square Corporate Campus, 16 Campus
Boulevard, Suite 150, Newtown Square, Pennsylvania; BRANDYWINE - MAIN STREET,
LLC ("BMS"), a Delaware limited liability company having an office at Newtown
Square Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
Pennsylvania; LC/N HORSHAM LIMITED PARTNERSHIP, a Pennsylvania limited
partnership; LC/N KEITH VALLEY LIMITED PARTNERSHIP I, a Pennsylvania limited
partnership; NICHOLS LANSDALE LIMITED PARTNERSHIP III, a Pennsylvania limited
partnership; NEWTECH III LIMITED PARTNERSHIP, a Pennsylvania limited
partnership; NEWTECH IV LIMITED PARTNERSHIP, a Pennsylvania limited partnership;
C/N OAKLANDS LIMITED PARTNERSHIP I, a Pennsylvania limited partnership; FIFTEEN
HORSHAM, L.P., a Pennsylvania limited partnership; C/N LEEDOM LIMITED
PARTNERSHIP II, a Pennsylvania limited partnership; C/N IRON RUN LIMITED
PARTNERSHIP III, a Pennsylvania limited partnership; all having offices c/o
Brandywine Realty Trust, Newtown Square Corporate Campus, 16 Campus Boulevard,
Suite 150, Newtown Square, Pennsylvania (collectively, the "BRT/BOP Limited
Partnerships"; BRT, BOP, BMS and the BRT/BOP Limited Partnerships are
<PAGE>

hereinafter collectively referred to as "Borrowers"); WITMER OPERATING
PARTNERSHIP I, L.P. ("WOP"), a Delaware limited partnership having an office at
Newtown Square Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
Pennsylvania; BRANDYWINE REALTY PARTNERS ("BRP"), a Pennsylvania general
partnership having an office at Newtown Square Corporate Campus, 16 Campus
Boulevard, Suite 150, Newtown Square, Pennsylvania; and BRANDYWINE REALTY
SERVICES CORPORATION ("BRSC"), a Pennsylvania corporation having an office at
Newtown Square Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
Pennsylvania (WOP, BRP and BRSC are hereinafter collectively referred to as
"Guarantors").

                              PRELIMINARY STATEMENT

            A. All capitalized terms used in this Amendment shall, unless
otherwise defined in the main body of this Amendment or in Exhibit A to this
Amendment, have the respective meanings given to such terms in the Credit
Agreement (hereinafter defined).

            B. Co-Lenders have, on the terms, covenants and provisions set forth
in that certain Revolving Credit Agreement dated as of November 25, 1996 (the
"Credit Agreement") and the other Credit Facility Documents, extended to
Borrowers a revolving credit facility in the principal sum of up to, but not in
excess of, $80,000,000 (the "Existing Credit Facility").
<PAGE>

            C. The Existing Credit Facility is evidenced by the Existing Credit
Facility Notes and secured by, among other things, the Existing Mortgages and
the Existing Assignments of Leases and Rents encumbering the collateral
properties identified on Exhibit B hereto (the "Existing Collateral
Properties").

            D. In connection with the Existing Credit Facility, (i) the
Guarantors have executed and delivered to Agent a certain Guaranty of Payment
dated as of November 25, 1996 (the "Guaranty of Payment") and (ii) the
Guarantors and Borrowers have executed and delivered to Agent a certain
Hazardous Material Guaranty and Indemnification Agreement dated as of November
25, 1996 (the "Hazardous Material Guaranty and Indemnification Agreement"; the
Guaranty of Payment and the Hazardous Material Guaranty and Indemnification
Agreement are collectively the "Guaranties").

            E. Borrowers have requested that Agent and Co-Lenders increase the
maximum principal amount available for draw under the Existing Credit Facility
from up to $80,000,000 to up to $150,000,000 in accordance with the provisions
of this Amendment hereinafter set forth.

            F. Agent and Co-Lenders are willing to increase the maximum
principal amount available for draw under the Existing Credit Facility from up
to $80,000,000 to up to $150,000,000 only if Borrowers and the Guarantors, as
applicable, agree to (i) modify, amend and restate the Existing Credit Facility
Notes, (ii) modify and amend the Existing Mortgages encumbering the
<PAGE>

Existing Collateral Properties, (iii) execute and deliver mortgages and
assignments of leases and rents with respect to the properties identified on
Exhibit C attached hereto (the "New Collateral Properties"), and (iv) modify and
amend the Existing Assignments of Leases and Rents, the Guaranties and all other
documents and instruments executed and delivered in connection with the Credit
Facility in accordance with the provisions of this Amendment.

            NOW, THEREFORE, in consideration of the foregoing and other good and
valuable consideration, the receipt and sufficiency of which is hereby
acknowledged, Agent, Co-Lenders, Borrowers and Guarantors hereby covenant and
agree as follows:

            1. Increase in Credit Facility. Subject to the terms and conditions
of the Credit Agreement, as modified and amended pursuant to the terms and
provisions of this Amendment, the maximum amount available for draw under the
Existing Credit Facility shall be increased by up to $70,000,000 (the "Credit
Facility Increase") from up to $80,000,000 to up to $150,000,000 (the Existing
Credit Facility, as so increased by the Credit Facility Increase, is hereinafter
the "Credit Facility"). The Credit Facility Percentage Interest held by each
Co-Lender in the Credit Facility (inclusive of risk participations in any Letter
of Credit which is issued and is outstanding under the Credit Facility) on the
date hereof and after giving effect to the Credit Facility Increase is as
follows:

================================================================================
                                    Amount      Percentage Interest
                                    ------      -------------------
- --------------------------------------------------------------------------------
Smith Barney                     $27,500,000           18.3334%
- --------------------------------------------------------------------------------
NationsBank                      $27,500,000           18.3334%
<PAGE>

- --------------------------------------------------------------------------------
First Chicago                    $20,000,000           13.3333%
- --------------------------------------------------------------------------------
Mellon                           $20,000,000           13.3333%
- --------------------------------------------------------------------------------
PNC                              $20,000,000           13.3333%
- --------------------------------------------------------------------------------
Summit                           $20,000,000           13.3333%
- --------------------------------------------------------------------------------
Signet                           $15,000,000           10.0000%
================================================================================

            2. Modification, Amendment and Restatement of Existing Credit
Facility Notes. The terms, covenants and provisions of each of the Credit
Facility Notes are contemporaneously being modified, amended and restated in
accordance with the provisions of the Amended and Restated Credit Facility Notes
in the form of Exhibit D-1 through Exhibit D-7 hereto, respectively (the
"Restated Credit Facility Notes"), which Restated Credit Facility Notes have
been executed and delivered by Borrowers to Co-Lenders contemporaneously with
the execution and delivery of this Amendment. Co-Lenders shall return to
Borrowers any Credit Facility Note with respect to which Restated Credit
Facility Notes are executed by Borrowers in accordance with the preceding
provisions of this paragraph, which replaced Credit Facility Note shall, prior
to being returned to Borrowers, be marked "cancelled and replaced pursuant to
the First Amendment to Revolving Credit Agreement and Other Credit Facility
Documents".

            3. Modification and Amendment of Existing Mortgages; Execution of
New Mortgages and New Assignments of Leases and Rents. (a) The terms, covenants
and provisions of each of the Existing Mortgages are contemporaneously being
modified and amended in accordance with the provisions of the Amendment of
Mortgage attached hereto as Exhibit E-1 (Pennsylvania), 
<PAGE>

Exhibit E-2 (New Jersey) and Exhibit E-3 (Delaware) (collectively, the "Mortgage
Modification Agreements"), which Mortgage Modification Agreements have been
executed and delivered by the applicable Borrowers to Agent contemporaneously
with the execution and delivery of this Amendment and are intended to be
promptly recorded in the appropriate recording office in each county in which
the Initial Collateral Properties are located. 

            (b) Contemporaneously with the execution and delivery of this
Amendment, BOP has executed and delivered (i) new mortgages in the form of
Exhibit F-1 (Pennsylvania) and Exhibit F-2 (New Jersey) attached hereto (the
"New Mortgages") with respect to each of the New Collateral Properties and (ii)
new assignments of leases and rents in the form of Exhibit G attached hereto
(the "New Assignments of Leases and Rents") with respect to each of the New
Collateral Properties, which New Mortgages and New Assignments of Leases and
Rents are intended to be promptly recorded in the appropriate recording office
in each county in which the New Collateral Properties are located.

            4. Modification of Credit Agreement Provisions. The Credit Agreement
is hereby modified and amended in the following respects:

                  (a) The definition of "Borrowers" appearing in the preamble to
the Credit Agreement is modified to include a reference to "BMS".

                  (b) Due to a scrivener's error in the Credit Agreement, the
defined term "BRSC" appears as "BRC" in subparagraph 22(a); accordingly, the
reference to "BRC" shall be deemed to refer to "BRSC".
<PAGE>

                  (c) The reference to "paragraph 11" contained in the
penultimate sentence of paragraph 8 of the Credit Agreement is hereby deleted
and replaced with a reference to "paragraph 12".

                  (d) The reference to "paragraph 15" contained in the first
sentence of subparagraph 23(n) of the Credit Agreement is hereby deleted and
replaced with a reference to "paragraph 16".

                  (e) Subparagraph 23(hh) of the Credit Agreement is hereby
deleted in its entirety and the following provision substituted therefor: 

            "(hh) From and after July 15, 1997, the aggregate Approved Value of
            all Properties from time to time constituting part of the collateral
            pool for the Credit Facility shall at all times be equal to or in
            excess of $140,000,000."

                  (f) The definition of "Co-Lenders" appearing in Exhibit A of
the Credit Agreement is hereby deleted in its entirety and the following
definition substituted therefor:

            "Co-Lenders: The term "Co-Lenders" as used in this Agreement shall
      mean, collectively, (i) Smith Barney, (ii) NationsBank, (iii) First
      Chicago, (iv) Mellon, (v) PNC, (vi) Summit, (vii) Signet, and (viii) all
      other parties from time to time to whom direct interests in the Credit
      Facility are sold, transferred and assigned and who are as a result
      thereof designated as Co-Lenders, under and pursuant to the provisions of
      this Agreement and the Co-Lenders Agreement."
<PAGE>

                  (g) The definition of "Credit Facility Notes" appearing in
Exhibit A of the Credit Agreement is hereby deleted in its entirety and the
following definition substituted therefor:

            "Credit Facility Notes: The term "Credit Facility Notes" as used in
      this Agreement shall mean, collectively, the following: (i) that certain
      Amended and Restated Note dated as of July 15, 1997 in the original
      principal amount of $27,500,000.00 given by Borrowers to Smith Barney,
      (ii) that certain Amended and Restated Note dated as of July 15, 1997 in
      the original principal amount of $27,500,000.00 given by Borrowers to
      NationsBank, (iii) that certain Amended and Restated Note dated as of July
      15, 1997 in the original principal amount of $20,000,000.00 given by
      Borrowers to First Chicago, (iv) that certain Amended and Restated Note
      dated as of July 15, 1997 in the original principal amount of
      $20,000,000.00 given by Borrowers to Mellon, (v) that certain Amended and
      Restated Note dated as of July 15, 1997 in the original principal amount
      of $20,000,000.00 given by Borrowers to PNC, (vi) that certain Amended and
      Restated Note dated as of July 15, 1997 in the original principal amount
      of $20,000,000.00 given by Borrowers to Summit, and (vii) that certain
      Amended and Restated Note dated as of July 15, 1997 in the original
      principal amount of $15,000,000.00 given by Borrowers to Signet, as such
      Amended and Restated Notes may from time to time be amended, modified,
      extended, supplemented, renewed, replaced or restated."

                  (h) The definition of "Unused Portion" appearing in Exhibit A
of the Credit Agreement is hereby deleted in its entirety and the following
definition substituted therefor:

            "Unused Portion: The term "Unused Portion" as used in this Agreement
      shall be calculated on a daily basis and shall mean, $150,000,000 less the
      sum of (i) the daily weighted average of the outstanding principal balance
      of the Credit Facility Notes and (ii) the daily weighted average of the
      aggregate amount available for draw under all outstanding Letters of
      Credit."

                  (i) The following additional definitions are inserted into
Exhibit A of the Credit Agreement in their appropriate alphabetical order:
<PAGE>

            "BMS: The term "BMS" as used in this Agreement shall mean Brandywine
      - Main Street, LLC, a Delaware limited liability company."

            "First Chicago: The term "First Chicago" as used in this Agreement
      shall mean The First National Bank of Chicago, a national banking
      association having an office at One First National Plaza, Chicago,
      Illinois."

            "Mellon: The term "Mellon" as used in this Agreement shall mean
      Mellon Bank, N.A., a national banking association having an office at 1735
      Market Street, Philadelphia, Pennsylvania."

            "PNC: The term "PNC" as used in this Agreement shall mean PNC Bank,
      National Association, a national banking association having an office at
      1600 Market Street, Philadelphia, Pennsylvania."

            "Signet: The term "Signet" as used in this Agreement shall mean
      Signet Bank, a state banking association organized under the laws of the
      Commonwealth of Virginia having an office at 7799 Leesburg Pike, 4th
      Floor, Falls Church, Virginia."

            "Summit: The term "Summit" as used in this Agreement shall mean
      Summit Bank, N.A., a state banking association organized under the laws of
      the State of New Jersey having an office at 1800 Chapel Avenue West,
      Cherry Hill, New Jersey."

                  (j) The dollar amount of "$80,000,000" contained in the
Preliminary Statement of each of Exhibit G (Form of Mortgage), Exhibit H (Form
of Deed of Trust) and Exhibit I (Form of Assignment of Leases) to the Credit
Agreement is hereby amended in each instance to reflect the dollar amount of
"$150,000,000".

                  (k) The phrase "Eighty Million and 00/100 Dollars
($80,000,000.00)" appearing in Paragraph E of the Preliminary Statement of each
of Exhibit G (Form of Mortgage) and Exhibit H (Form of Deed of Trust) to 
<PAGE>

the Credit Agreement is hereby deleted in its entirety and replaced with the
phrase "One Hundred Fifty Million and 00/100 Dollars ($150,000,000.00)".

            5. Modification of Existing Assignments of Leases and Rents
Provisions. Each of the Existing Assignments of Leases and Rents is hereby
modified and amended in the following respects:

            (a) The following definition is hereby inserted in Exhibit A of each
      of the Existing Assignments of Leases and Rents in its appropriate
      alphabetical order:

            "BMS: The term "BMS" as used in this Assignment shall mean
            Brandywine-Main Street, LLC, a Delaware limited liability company."

            (b) The definition of "Borrowers" appearing in Exhibit A of each of
      the Existing Assignments of Leases and Rents is deleted in its entirety
      and the following definition is substituted therefor: 

            "Borrowers: The term "Borrowers" as used in this Assignment shall
            collectively mean BRT, BOP, BMS and the BRT/BOP Limited
            Partnerships."

            (c) The definition of "Co-Lenders" appearing in Exhibit A of each of
      the Existing Assignments of Leases and Rents is deleted in its entirety
      and the following definition is substituted therefor: 

            "Co-Lenders: The term "Co-Lenders" as used in this Assignment shall
            mean, collectively, Smith Barney Mortgage Capital Group, Inc., a
            Delaware corporation, NationsBank, N.A., a national banking
            association, in its individual capacity, The First 
<PAGE>

            National Bank of Chicago, a national banking association, Mellon
            Bank, N.A., a national banking association, PNC Bank, National
            Association, a national banking association, Signet Bank, a state
            banking association organized under the laws of the Commonwealth of
            Virginia, Summit Bank, a state banking association organized under
            the laws of the State of New Jersey, and all other parties from time
            to time to whom direct interests in the Credit Facility are sold,
            transferred and assigned, and who are as a result thereof designated
            as Co-Lenders, under and pursuant to the provisions of the Credit
            Agreement and the Co-Lenders Agreement."

            6. Modification of Guaranty of Payment Provisions. The Guaranty of
Payment is hereby modified and amended in the following respects:

                  (a) The following definition is inserted in Exhibit A to the
Guaranty of Payment:

            "BMS: The term "BMS" as used in this Agreement shall mean Brandywine
      - Main Street, LLC, a Delaware limited liability company. "

                  (b) The definition of "Borrowers" appearing in Exhibit A to
the Guaranty of Payment is modified to include a reference to "BMS".

                  (c) The definition of "Co-Lenders" appearing in Exhibit A to
the Guaranty of Payment is deleted in its entirety and the following definition
is substituted therefor:

            "Co-Lenders: The term "Co-Lenders" as used in this Guaranty shall
      mean NationsBank, N.A., a national banking association, in its individual
      capacity, The First National Bank of Chicago, a national banking
      association, Mellon Bank, N.A., a national banking association, PNC Bank,
      National Association, a national banking association, Signet Bank, a state
      banking association organized under the laws of the Commonwealth of
      Virginia, Summit Bank, a state banking association organized under the
      laws of the State of New Jersey, and all other parties from time to time
      to whom direct interests in the Credit Facility are sold, transferred and
      assigned, and who are as a result thereof designated as Co-Lenders, under
      and pursuant to the provisions of the Credit Agreement and the Co-Lenders
      Agreement."
<PAGE>

            7. Modification of Hazardous Material Guaranty and Indemnification
Agreement Provisions. The Hazardous Material Guaranty and Indemnification
Agreement is hereby modified and amended in the following respects:

                  (a) The following definition is inserted in Exhibit A to the
Hazardous Material Guaranty and Indemnification Agreement:

            "BMS: The term "BMS" as used in this Guaranty and Indemnification
      Agreement shall mean Brandywine - Main Street, LLC, a Delaware limited
      liability company. "

                  (b) The definition of "Borrowers" appearing in Exhibit A to
the Hazardous Material Guaranty and Indemnification Agreement is modified to
include a reference to "BMS". 

                  (c) The definition of "Co-Lenders" appearing in Exhibit A to
the Hazardous Material Guaranty and Indemnification Agreement is deleted in its
entirety and the following definition is substituted therefor:

            "Co-Lenders: The term "Co-Lenders" as used in this Guaranty and
      Indemnification Agreement shall mean NationsBank, N.A., a national banking
      association, in its individual capacity, The First National Bank of
      Chicago, a national banking association, Mellon Bank, N.A., a national
      banking association, PNC Bank, National Association, a national banking
      association, Signet Bank, a state banking association organized under the
      laws of the Commonwealth of Virginia, Summit Bank, a state banking
      association organized under the laws of the State of New Jersey, and all
      other parties from time to time to whom direct interests in the Credit
      Facility are sold, transferred and assigned, and who are as a result
      thereof designated as Co-Lenders, under and pursuant to the provisions of
      the Credit Agreement and the Co-Lenders Agreement."

            8. Omnibus Modification of Other Credit Facility Documents. All
references in the Credit Facility Documents to the Existing Credit Facility
Notes shall be deemed to refer to the Existing Credit Facility Notes, as amended
and restated in accordance with the provisions of the Restated 
<PAGE>

Credit Facility Notes. All references in the Credit Facility Documents to the
Existing Mortgages shall be deemed to refer to the Existing Mortgages, as
modified and amended pursuant to the provisions of the Mortgage Modification
Agreements. All references in the Credit Facility Documents to the Credit
Agreement shall be deemed to refer to the Credit Agreement, as modified and
amended pursuant to the provisions of this Amendment. All references in the
Credit Facility Documents to the Existing Assignment of Leases and Rents shall
be deemed to refer to the Existing Assignment of Leases and Rents, as modified
and amended pursuant to the provisions of this Amendment. All references in the
Credit Facility Documents to the Guaranty of Payment shall be deemed to refer to
the Guaranty of Payment, as modified and amended pursuant to the provisions of
this Amendment. All references in the Credit Facility Documents to the Hazardous
Material Guaranty and Indemnification Agreement shall be deemed to refer to the
Hazardous Material Guaranty and Indemnification Agreement, as modified and
amended pursuant to the provisions of this Amendment.

            9. Payment of Commitment Fee. Borrowers agree that in consideration
of the Credit Facility Increase, Borrowers shall pay to Agent a commitment fee
in an amount of $385,000, which commitment fee shall be deemed earned in full by
Co-Lenders upon payment, shall be paid in full by Borrowers simultaneously with
the execution and delivery of this Amendment and shall be promptly distributed
by Agent to the Co-Lenders.
<PAGE>

            10. Agreements of Guarantors. (a) The Guarantors consent to the
Credit Facility Increase and acknowledge the continuing validity and
effectiveness of their joint and several obligations under the Guaranties (each
as modified and amended by the provisions of this Amendment) notwithstanding the
Credit Facility Increase and the modification, amendment and/or restatement of
the Credit Facility Documents in the manner contemplated by this Amendment, and
each of the undersigned represents, warrants and confirms that there are no
offsets, defenses or counterclaims to its obligations under the Guaranties.

      (b) The Guarantors reacknowledge and reaffirm and ratify and confirm all
of the terms and obligations contained in the Guaranties, each as modified and
amended by the provisions of this Amendment, and confirm that the Guaranties,
each as modified and amended by the provisions of this Amendment, shall remain
in full force and effect with respect to all of the obligations of Borrowers
under the Credit Facility Documents (as amended by this Amendment), and
acknowledge, agree, represent and warrant that no oral or other agreements,
understandings, representations or warranties exist with respect to the
Guaranties, each as modified and amended by the provisions of this Amendment, or
with respect to the obligations of the Guarantors thereunder (except as
expressly set forth in this Amendment).

      (c) Each of the Guarantors represents, warrants and confirms that no
material adverse change has occurred in its financial status since the original
extension of the Credit Facility, that (i) there are no judgments 
<PAGE>

against it in any of the courts of the United States and (ii) there is no
litigation (whether active, pending or threatened) against it, which, in either
case, might materially and adversely affect the ability of the Guarantors to pay
when due any amounts which may become payable in respect of the Guaranties, each
as modified and amended by the provisions of this Amendment.

            11. No Offsets, Defenses. Borrowers and Guarantors acknowledge and
agree that there are no offsets, defenses or counterclaims of any nature
whatsoever with respect (i) to the Credit Facility Documents, as modified and
amended pursuant to the terms and provisions of this Amendment or (ii) to the
payment of the indebtedness evidenced and secured by the Credit Facility
Documents, as modified and amended pursuant to the terms and provisions of this
Amendment.

            12. Absolute and Unconditional Obligation. Borrowers and Guarantors
acknowledge that the Credit Facility Documents, as modified, amended and/or
restated pursuant to (or in the manner contemplated by) the provisions of this
Amendment, and Borrowers' and Guarantors' obligations under the Credit Facility
Documents, as modified, amended and/or restated pursuant to (or in the manner
contemplated by) the provisions of this Amendment, are and shall at all times
continue to be absolute and unconditional in all respects, and shall at all
times be valid and enforceable irrespective of any other agreements or
circumstances of any nature whatsoever which might otherwise constitute a
defense to the Credit Facility Documents, as modified, 
<PAGE>

amended and/or restated pursuant to (or in the manner contemplated by) the
provisions of this Amendment, or the obligations of Borrowers or Guarantors
thereunder to pay the Debt or the obligations of any other Person relating to
the Credit Facility Documents, as modified, amended and/or restated pursuant to
(or in the manner contemplated by) the provisions of this Amendment or the
obligations of Borrowers or Guarantors under the Credit Facility Documents, as
modified, amended and/or restated pursuant to (or in the manner contemplated by)
the provisions of this Amendment or otherwise with respect to the Credit
Facility, and Borrowers and Guarantors absolutely, unconditionally and
irrevocably waive any and all right to assert any defense, setoff, counterclaim
or crossclaim of any nature whatsoever with respect to the obligation of the
Borrowers and Guarantors to pay the Debt in accordance with the provisions of
the Credit Facility Documents, as modified, amended and/or restated pursuant to
the provisions of this Amendment, or the obligations of any other Person
relating to the Credit Facility Documents, as modified, amended and/or restated
pursuant to (or in the manner contemplated by) the provisions of this Amendment,
or the obligations of Borrowers and Guarantors under the Credit Facility
Documents, as modified, amended and/or restated pursuant to (or in the manner
contemplated by) the provisions of this Amendment, or the obligations of
Borrowers and Guarantors hereunder or otherwise with respect to the Credit
Facility in any action, case or proceeding brought by Agent to collect the Debt
or any portion thereof, or to enforce, foreclose and realize upon the liens and
security interests created by the Credit Facility Documents, as modified,
amended and/or restated pursuant to (or in the manner contemplated by) the
provisions of this 
<PAGE>

Amendment (provided, however, that the foregoing provisions of this sentence
shall not be deemed a waiver of the rights of Borrowers or Guarantors to assert
any compulsory counterclaim in any such action, case or proceeding brought by
Agent or Co-Lenders in any state court if such counterclaim is compelled under
local law or rule or procedure, or in any such action, case or proceeding
brought by Agent or Co-Lenders in a court of the United States, nor shall the
foregoing provisions of this sentence be deemed a waiver of the rights of
Borrowers or Guarantors to assert any claim which would otherwise constitute a
defense, setoff, counterclaim or crossclaim of any nature whatsoever against
Agent or Co-Lenders in any separate action, case or proceeding brought by any of
the Borrowers or Guarantors against Agent or Co-Lenders).

            13. Governing Law, No Modifications, Successors and Assigns. This
Amendment shall be governed by the laws of the State of New York, shall not be
modified, cancelled or terminated except by an instrument in writing signed by
the parties hereto and shall inure to the benefit of and be binding upon the
parties hereto and their respective successors and assigns.

            14. Counterparts. This Amendment may be executed in one or more
counterparts by some or all of the parties hereto, each of which counterparts
shall be an original and all of which together shall constitute a single
agreement.

            15. Severability. If any term, covenant or provision of this
Amendment shall be held to be invalid, illegal or unenforceable in any 
<PAGE>

respect, this Amendment shall be construed without such term, covenant or
provision.

            16. Full Force and Effect. Except as expressly modified and amended
by the provisions of this Amendment, all of the terms, covenants and provisions
of the Credit Agreement and the other Credit Facility Documents shall remain in
full force and effect.

            17. Modification. EACH OF THE CREDIT AGREEMENT AND THE OTHER CREDIT
FACILITY DOCUMENTS, AS MODIFIED AND AMENDED BY THE EXPRESS PROVISIONS OF THIS
AMENDMENT, CONSTITUTES THE ENTIRE AGREEMENT OF THE PARTIES HERETO WITH RESPECT
TO THE SUBJECT MATTER THEREOF AND THERE ARE NO ORAL OR OTHER AGREEMENTS AMONG
THE PARTIES WITH RESPECT TO THE CREDIT AGREEMENT AND THE OTHER CREDIT FACILITY
DOCUMENTS, AS SO MODIFIED AND AMENDED, OR WITH RESPECT TO THE SUBJECT MATTER
THEREOF. THIS AMENDMENT SHALL NOT BE MODIFIED, AMENDED OR TERMINATED, EXCEPT BY
AN AGREEMENT IN WRITING SIGNED BY THE PARTIES HERETO.

            18. Due Execution. Each of the Co-Lenders, Agent, Borrowers and
Guarantors respectively represents for itself that this Amendment has been duly
executed and delivered by it and constitutes its binding and enforceable
obligation in accordance with its terms.

            19. Exculpation. No recourse shall be had for any obligation of BRT
under this Amendment or any of the other Credit Facility Documents or for any
claim based thereon or otherwise in respect thereof, against any past, present
or future trustee, shareholder, officer or employee of BRT, whether by 
<PAGE>

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
each other party to this Amendment and the other Credit Facility Documents. No
recourse shall be had for any obligation of BRP under this Amendment or any of
the other Credit Facility Documents or for any claim based thereon or otherwise
in respect thereof, against Brandywine Specified Property Investors Limited
Partnership, a Pennsylvania limited partnership and one of the general partners
of BRP, 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 each other party to and beneficiary of this Amendment and
by each of the other general partners of BRP.
<PAGE>

            IN WITNESS WHEREOF, Co-Lenders, Borrowers, Guarantors and Agent have
caused this Amendment to be duly executed as of the day and year first above
written. 

                                    SMITH BARNEY MORTGAGE CAPITAL GROUP, INC.


                                    By:    /s/ Clive Bull
                                          ------------------------------------
                                          Name:   Clive Bull
                                          Title:  Vice President

                                    NATIONSBANK, N.A.


                                    By:   /s/ Cheryl D. Fitzgerald
                                          ------------------------------------
                                         Name:   Cheryl D. Fitzgerald
                                         Title:  Vice President

                                    THE FIRST NATIONAL BANK OF CHICAGO


                                    By:    /s/ Gregory A. Gilbert
                                          ------------------------------------
                                          Name:   Gregory A. Gilbert
                                          Title:  Vice President

                                    MELLON BANK, N.A.


                                    By:   /s/ Frederick A. Felter
                                          ------------------------------------
                                         Name:  Frederick A. Felter
                                         Title: Vice President

                                    PNC BANK, NATIONAL ASSOCIATION


                                    By:   /s/ Robert C. Ballard
                                          ------------------------------------
                                         Name:  Robert C. Ballard
                                         Title: Vice President
<PAGE>

                                    SIGNET BANK


                                    By:   /s/ Barry E. Cooper
                                         ------------------------------------
                                         Name:   Barry E. Cooper
                                         Title:  Vice President

                                    SUMMIT BANK, N.A.


                                    By:    /s/ Robert F. Follet
                                          -----------------------------------
                                          Name:   Robert F. Follet
                                          Title:  Vice President
<PAGE>

                                    NATIONSBANK, N.A., as Agent


                                    By:   /s/ Cheryl D. Fitzgerald
                                          -----------------------------------
                                         Name:  Cheryl D. Fitzgerald
                                         Title: Vice President

                                    BRANDYWINE REALTY TRUST, a Maryland real 
                                    estate investment trust


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

                                    BRANDYWINE OPERATING PARTNERSHIP, L.P.

                                    By:  Brandywine Realty Trust, a Maryland 
                                         real estate investment trust, its 
                                         general partner


                                            By:  /s/ Gerard H. Sweeney
                                                 ----------------------------
                                                 Name:   Gerard H. Sweeney
                                                 Title:  President and Chief
                                                         Executive Officer
<PAGE>

                                    BRANDYWINE - MAIN STREET, LLC, a Delaware 
                                    limited liability company

                                    By:  Brandywine Operating Partnership, 
                                         L.P., a Delaware limited 
                                         partnership, a member

                                         By:  Brandywine Realty Trust, a 
                                              Maryland real estate 
                                              investment trust


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

                                    By:  Brandywine Acquisitions, LLC, a 
                                         Delaware limited liability company, 
                                         a member

                                         By:  Brandywine Operating 
                                              Partnership, L.P., a Delaware 
                                              limited partnership

                                              By:  Brandywine Realty Trust,
                                                   a Maryland real estate
                                                   investment trust


                                                   By: /s/ Gerard H. Sweeney
                                                      -----------------------
                                                   Name: Gerard H. Sweeney
                                                   Title:  President and
                                                      Chief Executive
                                                      Officer
<PAGE>

                                LC/N HORSHAM LIMITED PARTNERSHIP, a Pennsylvania
                                limited partnership

                                LC/N KEITH VALLEY LIMITED PARTNERSHIP I, a 
                                Pennsylvania limited partnership

                                NICHOLS LANSDALE LIMITED PARTNERSHIP III, a 
                                Pennsylvania limited partnership

                                NEWTECH III LIMITED PARTNERSHIP, a Pennsylvania 
                                limited partnership

                                NEWTECH IV LIMITED PARTNERSHIP, a Pennsylvania 
                                limited partnership

                                C/N OAKLANDS LIMITED PARTNERSHIP I, a 
                                Pennsylvania limited partnership

                                FIFTEEN HORSHAM, L.P., a Pennsylvania limited 
                                partnership

                                By:  Witmer Operating Partnership I, L.P., a 
                                     Delaware limited partnership, its general 
                                     partner

                                     By:  Brandywine Holdings I, Inc., a
                                          Pennsylvania corporation, its
                                          general partner


                                           By: /s/ Gerard H. Sweeney
                                               --------------------------------
                                               Name:   Gerard H. Sweeney
                                               Title:  President and Chief
                                                       Executive Officer
<PAGE>

                                C/N LEEDOM LIMITED PARTNERSHIP II, a 
                                Pennsylvania limited partnership

                                C/N IRON RUN LIMITED PARTNERSHIP III, a 
                                Pennsylvania limited partnership

                                By:  Brandywine Operating Partnership, L.P., a
                                     Delaware limited partnership, its general 
                                     partner

                                     By:  Brandywine Realty Trust, a Maryland 
                                          real estate investment trust, its 
                                          general partner


                                          By: /s/ Gerard H. Sweeney
                                             ----------------------------------
                                             Name:   Gerard H. Sweeney
                                             Title:  President and Chief
                                                      Executive Officer
<PAGE>

                                WITMER OPERATING PARTNERSHIP I, L.P., a Delaware
                                limited partnership

                                By:  Brandywine Holdings I, Inc., a 
                                     Pennsylvania corporation, its general 
                                     partner


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

                                BRANDYWINE REALTY PARTNERS, a Pennsylvania 
                                general partnership

                                By:  Brandywine Realty Trust, a Maryland real 
                                     estate investment trust, its general 
                                     partner


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

                                BRANDYWINE REALTY SERVICES CORPORATION, a 
                                Pennsylvania corporation


                                By:   /s/ Gerard H. Sweeney
                                     ------------------------------------------
                                     Name:   Gerard H. Sweeney
                                     Title:  President and Chief
                                             Executive Officer
<PAGE>

                                    EXHIBIT A

Existing Mortgages: Collectively, the following:

      Open - End Mortgage and Security Agreement dated as of November 25, 1996
      given by LC/N Horsham Limited Partnership to Agent and recorded on January
      8, 1997 in Mortgage Book 7878, Page 0460 in the Recorder's Office of
      Montgomery County, Pennsylvania [Keith Valley 1]

      Open - End Mortgage and Security Agreement dated as of November 25, 1996
      given by LC/N Keith Valley Limited Partnership I to Agent and recorded on
      January 8, 1997 in Mortgage Book 7878, Page 0442 in the Recorder's Office
      of Montgomery County, Pennsylvania [Keith Valley 7]

      Open - End Mortgage and Security Agreement dated as of November 25, 1996
      given by Nichols Lansdale Limited Partnership III to Agent and recorded on
      January 8, 1997 in Mortgage Book 7878, Page 0844 in the Recorder's Office
      of Montgomery County, Pennsylvania [Lansdale]

      Open - End Mortgage and Security Agreement dated as of November 25, 1996
      given by Newtech III Limited Partnership to Agent and recorded on January
      6, 1997 in Volume 1548, Page 0269 in the Office of the Recorder of Deeds
      of Delaware County, Pennsylvania [Newtown 12]

      Open - End Mortgage and Security Agreement dated as of November 25, 1996
      given by Newtech IV Limited Partnership to Agent and recorded on January
      6, 1997 in Volume 1548, Page 0234 in the Office of the Recorder of Deeds
      of Delaware County, Pennsylvania [Newtown 11]

      Open - End Mortgage and Security Agreement dated as of November 25, 1996
      given by C/N Oaklands Limited Partnership I to Agent and recorded on
      January 7, 1997 in Book 4127, Page 0325 in the Office of the Recorder of
      Deeds of Chester County, Pennsylvania [Oaklands 5]

      Open - End Mortgage and Security Agreement dated as of November 25, 1996
      given by Fifteen Horsham, L.P. to Agent and recorded on January 8, 1997 in
      Mortgage Book 7878, Page 0423 in the Recorder's Office of Montgomery
      County, Pennsylvania [Horsham 15]

      Open - End Mortgage and Security Agreement dated as of November 25, 1996
      given by C/N Iron Run Limited Partnership III to Agent and recorded on
      January 6, 1997 in Mortgage Volume 2070, Page 1046 in the Office of the
      Recorder of Deeds of Lehigh County, Pennsylvania [Iron Run 3]

      Open - End Mortgage and Security Agreement dated as of November 25, 1996
      given by BOP to Agent and recorded on January 13, 1997 in Mortgage Book
<PAGE>

      7880, Page 0790 in the Recorder's Office of Montgomery County,
      Pennsylvania [700/800 Horsham]

      Mortgage dated as of November 25, 1996 given by BOP to Agent and recorded
      on January 6, 1997 in Book 4452, Page 0093 in the Office of the Recorder
      of Deeds of New Castle County, Delaware [Delaware Corporate Center]

      Mortgage dated as of November 25, 1996 given by BOP to Agent and recorded
      on January 2, 1997 in Mortgage Book 6593, Page 0309 in the Clerk's Office
      of Burlington County, New Jersey [8000 Lincoln Drive]

      Open-End Mortgage and Security Agreement dated as of November 25, 1996
      given by BOP to Agent and recorded on January 17, 1997 in Book 1344, Page
      0929 in the Office of the Recorder of Deeds of Bucks County, Pennsylvania
      [Bucks County Business Park]

      Open-End Mortgage and Security Agreement dated as of November 25, 1996
      given by BOP to Agent and recorded on January 7, 1997 in Book 1338, Page
      2364 in the Office of the Recorder of Deeds of Bucks County, Pennsylvania
      [1, 2, 3 Greenwood Square]

      Open - End Mortgage and Security Agreement dated as of November 25, 1996
      given by BOP to Agent and recorded on January 13, 1997 in Mortgage Book
      7880, Page 0894 in the Recorder's Office of Montgomery County,
      Pennsylvania [500 N. Gulph Rd.]

      Mortgage dated as of May 21, 1997 given by BOP to Agent and recorded on
      June 11, 1997 in Mortgage Book 6799, Page 55 in the Clerk's Office of
      Burlington County, New Jersey [Marlton Executive Court]

      Open - End Mortgage and Security Agreement dated as of May 21, 1997 given
      by BOP to Agent and recorded on June 25, 1997 in Mortgage Book 7959, Page
      96 in the Recorder's Office of Montgomery County, Pennsylvania [King
      Manor]

      Open - End Mortgage and Security Agreement dated as of May 21, 1997 given
      by BOP to Agent and recorded on June 26, 1997 in Record Book 4194, Page
      921 in the Office of the Recorder of Deeds of Chester County, Pennsylvania
      [Goshen]

      Mortgage dated as of May 29, 1997 given by BMS to Agent and recorded on
      ____________, 1997 in Mortgage Book ____, Page __ the office of the
      __________________ of Camden County, New Jersey [Main Street]

Existing Assignments of Leases and Rents: Collectively, the following:

      Assignment of Leases and Rents dated as of November 25, 1996 given by LC/N
      Horsham Limited Partnership to Agent and recorded on January 8, 
<PAGE>

      1997 in Deed Book 5173, Page 1741 in the Recorder's Office of Montgomery
      County, Pennsylvania [Keith Valley 1]

      Assignment of Leases and Rents dated as of November 25, 1996 given by LC/N
      Keith Valley Limited Partnership I to Agent and recorded on January 8,
      1997 in Deed Book 5173, Page 1730 in the Recorder's Office of Montgomery
      County, Pennsylvania [Keith Valley 7]

      Assignment of Leases and Rents as of November 25, 1996 given by Nichols
      Lansdale Limited Partnership III to Agent and recorded on January 8, 1997
      in Deed Book 5173, Page 1771 in the Recorder's Office of Montgomery
      County, Pennsylvania [Lansdale]

      Assignment of Leases and Rents dated as of November 25, 1996 given by
      Newtech III Limited Partnership to Agent and recorded on January 6, 1997
      in Volume 1548, Page 0287 in the Office of the Recorder of Deeds of
      Delaware County, Pennsylvania [Newtown 12]

      Assignment of Leases and Rents dated as of November 25, 1996 given by
      Newtech IV Limited Partnership to Agent and recorded on January 6, 1997 in
      Volume 1548, Page 0256 in the Office of the Recorder of Deeds of Delaware
      County, Pennsylvania [Newtown 11]

      Assignment of Leases and Rents dated as of November 25, 1996 given by C/N
      Oaklands Limited Partnership I to Agent and recorded on January 7, 1997 in
      Book 4127, Page 0344 in the Office of the Recorder of Deeds of Chester
      County, Pennsylvania [Oaklands 5]

      Assignment of Leases and Rents dated as of November 25, 1996 given by
      Fifteen Horsham, L.P. to Agent and recorded on January 8, 1997 in Deed
      Book 5173, Page 1718 in the Recorder's Office of Montgomery County,
      Pennsylvania [Horsham 15]

      Assignment of Leases and Rents dated as of November 25, 1996 given by C/N
      Iron Run Limited Partnership III to Agent and recorded on January 6, 1997
      in Volume 0838, Page 1027 in the Office of the Recorder of Deeds of Lehigh
      County, Pennsylvania [Iron Run 3]

      Assignment of Leases and Rents dated as of November 25, 1996 given by BOP
      to Agent and recorded on January 13, 1997 in Deed Book 5174, Page 0451 in
      the Recorder's Office of Montgomery County, Pennsylvania [700/800 Horsham]

      Assignment of Leases and Rents dated as of November 25, 1996 given by BOP
      to Agent and recorded on January 6, 1997 in Book 2220, Page 0001 in the
      Office of the Recorder of Deeds of New Castle County, Delaware [Delaware
      Corporate Center]

      Assignment of Leases and Rents dated as of November 25, 1996 given by BOP
      to Agent and recorded on January 2, 1997 in Deed Book 5272, Page 177 
<PAGE>

      in the Clerk's Office of Burlington County, New Jersey [8000 Lincoln
      Drive]

      Assignment of Leases and Rents dated as of November 25, 1996 given by BOP
      to Agent and recorded on January 17, 1997 in Book 1344, Page 0951 in the
      Office of the Recorder of Deeds of Bucks County, Pennsylvania [Bucks
      County Business Park]

      Assignment of Leases and Rents dated as of November 25, 1996 given by BOP
      to Agent and recorded on January 7, 1997 in Book 1338, Page 2365 in the
      Office of the Recorder of Deeds of Bucks County, Pennsylvania [1, 2, 3
      Greenwood Square]

      Assignment of Leases and Rents dated as of November 25, 1996 given by BOP
      to Agent and recorded on January 13, 1997 in Deed Book 5174, Page 0484 in
      the Recorder's Office of Montgomery County, Pennsylvania [500 N. Gulph
      Rd.]

      Assignment of Leases and Rents dated as of May 21, 1997 given by BOP to
      Agent and recorded on June 11, 1997 in Deed Book 5369, Page 313 in the
      Clerk's Office of Burlington County, New Jersey [Marlton Executive Court]

      Assignment of Leases and Rents dated as of May 21, 1997 given by BOP to
      Agent and recorded on June 25, 1997 in Deed Book 5190, Page 82 in the
      Recorder's Office of Montgomery County, Pennsylvania [King Manor]

      Assignment of Leases and Rents dated as of May 21, 1997 given by BOP to
      Agent and recorded on June 26 1997 in Record Book 4194, Page 992 in the
      Office of the Recorder of Deeds of Chester County, Pennsylvania [Goshen]

      Assignment of Leases and Rents dated as of May 29, 1997 given by BMS to
      Agent and recorded on ____________, 1997 in Book ____, Page ____ in the
      office of the __________________ of Camden County, New Jersey [Main
      Street]
<PAGE>

Existing Credit Facility Notes: Collectively, the following:

      Note dated as of April 4, 1997 in the principal sum of $10,000,000 made
      payable to PNC given by BRT, BOP and the BRT/BOP Limited Partnerships and
      subsequently joined in by BMS pursuant to the terms of that certain
      Joinder and Assumption Agreement dated as of May 29, 1997.

      Note dated as of April 4, 1997 in the principal sum of $10,000,000 made
      payable to Signet given by BRT, BOP and the BRT/BOP Limited Partnerships
      and subsequently joined in by BMS pursuant to the terms of that certain
      Joinder and Assumption Agreement dated as of May 29, 1997.

      Note dated as of April 4, 1997 in the principal sum of $10,000,000 made
      payable to Summit given by BRT, BOP and the BRT/BOP Limited Partnerships
      and subsequently joined in by BMS pursuant to the terms of that certain
      Joinder and Assumption Agreement dated as of May 29, 1997.

      Note dated as of April 4, 1997 in the principal sum of $10,000,000 made
      payable to Mellon given by BRT, BOP and the BRT/BOP Limited Partnerships
      and subsequently joined in by BMS pursuant to the terms of that certain
      Joinder and Assumption Agreement dated as of May 29, 1997.

      Note dated as of April 9, 1997 in the principal sum of $15,000,000 made
      payable to NationsBank given by BRT, BOP and the BRT/BOP Limited
      Partnerships and subsequently joined in by BMS pursuant to the terms of
      that certain Joinder and Assumption Agreement dated as of May 29, 1997.

      Note dated as of April 9, 1997 in the principal sum of $15,000,000 made
      payable to Smith Barney given by BRT, BOP and the BRT/BOP Limited
      Partnerships and subsequently joined in by BMS pursuant to the terms of
      that certain Joinder and Assumption Agreement dated as of May 29, 1997.

      Note dated as of April 9, 1997 in the principal sum of $10,000,000 made
      payable to First Chicago given by BRT, BOP and the BRT/BOP Limited
      Partnerships and subsequently joined in by BMS pursuant to the terms of
      that certain Joinder and Assumption Agreement dated as of May 29, 1997.
<PAGE>

                                    Exhibit B

                        (Existing Collateral Properties)

<TABLE>
<CAPTION>
             Name                              Address                Owner
- -------------------------------  ---------------------------------  --------------------------

        <S>                      <C>                                <C>
        Keith Valley 1           One Progress Avenue,               LC/N Horsham
                                 Montgomery County, PA              Limited Partnership

        Keith Valley 7           500 Enterprise Road,               LC/N Keith Valley
                                 Montgomery County, PA              Limited Partnership I

        Lansdale 150             1510 Gehman Road,                  Nichols Lansdale
                                 Montgomery County, PA              Limited Partnership III

        Newtown 12               16 Campus Boulevard,               Newtech III
                                 Delaware  County, PA               Limited Partnership

        Newtown 11               18 Campus Boulevard,               Newtech IV
                                 Delaware  County, PA               Limited Partnership

        Oaklands 5               456 Creamery Way, Chester          C/N Oaklands
                                 County, PA                         Limited Partnership I

        Horsham 15               1155 Business Center Drive,        Fifteen Horsham, L.P.
                                 Montgomery County, PA

        Iron Run 3               7248 Tilghman, Lehigh              C/N Iron Run
                                 County, PA                         Limited Partnership III

        700 & 800 Horsham        700 & 800 Horsham Business         BOP
        Business Center (2       Center, Montgomery County, 
        buildings)               PA

        Delaware Corp. Center 1  Delaware Corp. Center 1,           BOP
                                 New Castle County, DE

        8000 Lincoln Drive       8000 Lincoln Drive,                BOP
                                 Burlington County, NJ
 
        Bucks County Business    2200, 2250, 2260/2270 and          BOP
        Park                     3000 Cabot Boulevard, Bucks 
                                 County, PA

        One/Two/Three Greenwood  33 Street Road, Bucks              BOP
        Square (3 buildings)     County, PA

        500 N. Gulph Road        500 N. Gulph Road,                 BOP
                                 Montgomery County, PA

        Executive Court          2, 4A and 4B Eves Drive,           BOP
        (3 buildings)            Evesham Corporate Center, 
                                 Evesham Township,
</TABLE>
<PAGE>

<TABLE>
        <S>                      <C>                                <C>
                                 Burlington County, NJ

        King Manor Drive         201 and 221 King Manor             BOP
        (2 buildings)            Drive,
                                 King of Prussia, Upper 
                                 Merion Township, Montgomery 
                                 County, PA

        Goshen                   1336 Enterprise Drive              BOP
                                 East Goshen Township
                                 Chester County, PA

        Main Street              Main Street,                       BMS
                                 Voorhees Township
                                 Camden County, NJ
</TABLE>
<PAGE>

                                    Exhibit C

                           (New Collateral Properties)

           Name                              Address               Owner
- ----------------------------   ----------------------------------  -------------



      Greentree                1000, 2000, 3001, 3002,             BOP
      Executive Campus         3003, 4000 and 5000 
                               Greentree Executive Campus, 
                               Evesham, Burlington County, 
                               NJ

      Five Eves Drive          5 Eves Drive, Evesham               BOP
                               Corporate Center, Marlton, 
                               Burlington County,  NJ

      Sproul Road              1974 Sproul Road, Marple            BOP
                               Township, Delaware County, 
                               PA

      Oxford                   2000-2010 Cabot Boulevard,          BOP
                               Langhorne, Bucks County, PA

      Springhouse              321-323 Norristown Road,            BOP
                               Lower Gwynedd Township, 
                               Montgomery County, PA

      Greentree Commons        9001-9004 Lincoln Drive             BOP
                               West, Marlton, Burlington 
                               County, NJ

      Highlands                Highlands Business Center,          BOP
                               Westampton, Burlington 
                               County, NJ

      2,000-4,000              2000-4000 Midlantic Drive,          BOP
      Midlantic Drive          Mt. Laurel, Burlington County, 
                               NJ

      9,000 Midlantic          9000 Midlantic Drive, Mt.           BOP
      Drive                    Laurel, Burlington County, NJ

      10,000 Midlantic         10000 Midlantic Drive, Mt.          BOP
      Drive                    Laurel, Burlington County, 
                               NJ

      15,000 Midlantic         15000 Midlantic Drive, Mt.          BOP
      Drive                    Laurel, Burlington County, 
                               NJ
<PAGE>

      7,000 Geerdes            7000 Geerdes Boulevard,             BOP
      Boulevard                Upper Merion Township, 
                               Montgomery County, PA

      Springdale               748 and 855 Springdale              BOP
                               Drive,
                               Whiteland Township, Chester
                               County, PA
<PAGE>

                                Exhibit D-1 - D-7

                    (Forms of Restated Credit Facility Notes)

                                   Exhibit D-1

                            AMENDED AND RESTATED NOTE
                           (Revolving Credit Facility)

$27,500,000.00                                                New York, New York
                                                             As of July 15, 1997

            FOR VALUE RECEIVED, Brandywine Realty Trust, a Maryland real estate
investment trust, Brandywine Operating Partnership, L.P., a Delaware limited
partnership, LC/N Horsham Limited Partnership, a Pennsylvania limited
partnership; LC/N Keith Valley Limited Partnership I, a Pennsylvania limited
partnership; Nichols Lansdale Limited Partnership III, a Pennsylvania limited
partnership; Newtech III Limited Partnership, a Pennsylvania limited
partnership; Newtech IV Limited Partnership, a Pennsylvania limited partnership;
C/N Oaklands Limited Partnership I, a Pennsylvania limited partnership; Fifteen
Horsham, L.P., a Pennsylvania limited partnership; C/N Leedom Limited
Partnership II, a Pennsylvania limited partnership; C/N Iron Run Limited
Partnership III, a Pennsylvania limited partnership; Brandywine-Main Street,
LLC, a Delaware limited liability company, each having an office at Newtown
Square Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
Pennsylvania (hereinafter collectively referred to as "Maker"), promise to pay
NationsBank, N.A., a national banking association having an office at 8300
Greensboro Drive, McLean, Virginia (hereinafter referred to as "Payee") or
order, at such place as may be designated from time to time in writing by Payee,
the principal sum of Twenty-Seven Million Five Hundred Thousand and 00/100
Dollars ($27,500,000.00) in lawful money of the United States of America, or so
much thereof as may be advanced and readvanced by Payee to Maker and be
outstanding from time to time in accordance with the provisions of the Credit
Agreement, with interest thereon from and including the date of this Note to,
but not including, the date this Note is paid in full, calculated in the manner
hereinafter set forth, as follows:

                  20. interest on the Principal Balance calculated in the manner
      set forth in the Credit Agreement shall be due and payable in Federal
      funds or other immediately available funds on each Re-Set Date during the
      term of this Note and otherwise in accordance with the provisions of the
      Credit Agreement; and

                  21. the entire Principal Balance, together with all interest
      accrued and unpaid thereon calculated in the manner set forth in the
      Credit Agreement and all other sums due under this Note, shall be due and
      payable on the Maturity Date and otherwise in accordance with the
      provisions of the Credit Agreement.
<PAGE>

            II. The term "Credit Agreement" as used in this Note means a certain
Revolving Credit Agreement dated as of November 25, 1996 entered into among
Smith Barney Mortgage Capital Group, Inc., NationsBank, N.A., in its individual
capacity, Maker and NationsBank, N.A., acting in its capacity as administrative
and documentation agent for the Credit Facility, as the same may be modified or
amended from time to time, and pursuant to the provisions of which the Credit
Facility has been extended by Co-Lenders to Maker. This Note constitutes one of
the Credit Facility Notes which have been executed and delivered by Maker to
Co-Lenders in accordance with the Credit Agreement and which together evidence
the Credit Facility. All other capitalized terms used in this Note shall, unless
otherwise defined in this Note, have the meaning given to such term in the
Credit Agreement.

            III. It is hereby expressly agreed that the entire Debt shall become
immediately due and payable at the option of Co-Lenders on the happening of any
Event of Default.

            IV. All of the terms, covenants and provisions contained in the
Credit Agreement and the other Credit Facility Documents which are to be kept
and performed by Maker are hereby made part of this Note to the same extent and
with the same force and effect as if they were fully set forth herein. Maker
agrees to perform and comply with each of the terms, covenants and provisions
contained in this Note, the Credit Agreement and the other Credit Facility
Documents on the part of Maker to be observed and performed.

            V. If any installment of interest payable under this Note is not
paid when due, Maker shall pay to Agent upon demand an amount equal to four
percent (4%) of such unpaid installment as a late payment charge.

            VI. In addition to any late payment charge which may be due under
this Note, if the Debt is declared immediately due and payable pursuant to the
provisions of the Credit Facility Documents, or if the Debt is not paid in full
on the Maturity Date, Maker shall thereafter pay interest on the then entire
outstanding Principal Balance from the date of such declaration or the Maturity
Date, as the case may be, until the date the Principal Balance is paid in full,
at the Default Rate. In addition, if an Event of Default shall occur, the
Principal Balance shall, from and including the date upon which such Event of
Default has occurred and for so long as such Event of Default continues and
without further act or instrument and without the necessity of any further or
prior notice by Payee or Agent to Maker, bear interest at the Default Rate
irrespective of whether the Debt shall have been declared to be immediately due
and payable as the result of the occurrence of such Event of Default.

            VII. Maker hereby waives presentment and demand for payment, notice
of dishonor, protest and notice of protest of this Note. If any payment under
this Note is not made when due, Maker agrees to pay all costs of collection when
incurred, including reasonable attorneys' fees (which costs shall be added to
the amount due under this Note and shall be receivable therewith). No release of
any security for the payment of this Note or extension of time for payment of
this Note, or any installment hereof, and no alteration, amendment or waiver of
any provision of this Note or any of the 
<PAGE>

other Credit Facility Documents made by agreement between or among Co-Lenders,
Agent and/or Payee and any other person or party shall release, discharge,
modify, change or affect the liability of Maker under this Note or any of the
other Credit Facility Documents.

            VIII. This Note is subject to the express condition that at no time
shall Maker be obligated or required to pay interest on the Principal Balance at
a rate which could subject Payee to either civil or criminal liability as a
result of being in excess of the maximum rate which Maker is permitted by law to
contract or agree to pay. If by the terms of this Note Maker is at any time
required or obligated to pay interest on the Principal Balance at a rate in
excess of such maximum rate, the rate of interest under this Note shall be
deemed to be immediately reduced to such maximum rate and interest payable
hereunder shall be computed at such maximum rate and the portion of all prior
interest payments in excess of such maximum rate shall be applied and shall be
deemed to have been payments in reduction of the Principal Balance.

            IX. If Maker consists of more than one person or party, the
obligations and liabilities of each such person or party hereunder shall be
joint and several.

            X. Except as otherwise specifically provided to the contrary in the
Credit Facility Documents, this Note is secured on a pari passu basis with the
other Credit Facility Notes by the Mortgages and the other Credit Facility
Documents.

            XI. The terms of this Note shall be governed by and construed under
the laws of the State of New York.

            XII. This Note may only be modified, amended, changed or terminated
by an agreement in writing signed by Payee, Agent and Maker. No waiver of any
term, covenant or provision of this Note shall be effective unless given in
writing by Payee and Agent and if so given by Payee and Agent shall only be
effective in the specific instance in which given.

            XIII. Maker acknowledges that this Note and Maker's obligations
under this Note are and shall at all times continue to be absolute and
unconditional in all respects, and shall at all times be valid and enforceable
irrespective of any other agreements or circumstances of any nature whatsoever
which might otherwise constitute a defense (other than a defense of payment) to
this Note and the obligations of Maker under this Note or the obligations of any
other person or party relating to this Note or the obligations of Maker
hereunder or otherwise with respect to the Credit Facility. Maker absolutely,
unconditionally and irrevocably waives any and all right to assert any defense,
setoff, counterclaim (other than a compulsory counterclaim in a court of
competent jurisdiction) or crossclaim of any nature whatsoever with respect to
this Note or the obligations of Maker under this Note or the obligations of any
other person or party relating to this Note or the obligations of Maker
hereunder or otherwise with respect to the Credit Facility in any action, case
or proceeding brought by Payee or Agent to collect the Debt, or any portion
thereof, or to enforce, foreclose and realize upon the liens and security
<PAGE>

interests created by the Mortgages and the other Credit Facility Documents
(provided, however, that the foregoing provisions of this sentence shall not be
deemed a waiver of the right of Maker to assert any compulsory counterclaim in
any such action, case or proceeding brought by Payee or Agent in any state court
if such counterclaim is compelled under local law or rule or procedure, or in
any such action, case or proceeding brought by Payee or Agent in a court of the
United States, nor shall the foregoing provisions of this sentence be deemed a
waiver of the right of Maker to assert any claim which would otherwise
constitute a defense, setoff, counterclaim or crossclaim of any nature
whatsoever against Payee or Agent in any separate action, case or proceeding
brought by Maker against Payee or Agent). MAKER ACKNOWLEDGES THAT NO ORAL OR
OTHER AGREEMENTS, UNDERSTANDINGS, REPRESENTATIONS OR WARRANTIES EXIST WITH
RESPECT TO THIS NOTE OR WITH RESPECT TO THE OBLIGATIONS OF MAKER UNDER THIS
NOTE, EXCEPT THOSE SPECIFICALLY SET FORTH IN THIS NOTE AND THE OTHER CREDIT
FACILITY DOCUMENTS, AND THAT THIS NOTE AND THE OTHER CREDIT FACILITY DOCUMENTS
SET FORTH THE ENTIRE AGREEMENT AND UNDERSTANDING OF PAYEE, AGENT, CO-LENDERS AND
MAKER.

            XIV. No delay on the part of Payee, Agent or Co-Lenders in
exercising any right or remedy under this Note or the other Credit Facility
Documents or failure to exercise the same shall operate as a waiver in whole or
in part of any such right or remedy. No notice to or demand on Maker shall be
deemed to be a waiver of the obligation of Maker or of the right of Payee, Agent
or Co-Lender to take further action without further notice or demand as provided
in this Note and the other Credit Facility Documents.

            XV. Maker agrees to submit to personal jurisdiction in the State of
New York in any action, case or proceeding arising out of this Note and, in
furtherance of such agreement, Maker hereby agrees and consents that without
limiting other methods of obtaining jurisdiction, personal jurisdiction over
Maker in any such action, case or proceeding may be obtained within or without
the jurisdiction of any court located in New York and that any process or notice
of motion or other application to any such court in connection with any such
action, case or proceeding may be served upon Maker by registered or certified
mail to or by personal service at the last known address of Maker, whether such
address be within or without the jurisdiction of any such court. Maker also
agrees that the venue of any litigation arising in connection with the Debt or
in respect of any of the obligations of Maker under this Note shall, to the
extent permitted by law, be in New York County.

            XVI. Maker (and the undersigned representative of Maker, if any)
represents that Maker has full power, authority and legal right to execute and
deliver this Note and that this Note constitutes a valid and binding obligation
of Maker.

            XVII. MAKER HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES, AND PAYEE
BY ITS ACCEPTANCE OF THIS NOTE IRREVOCABLY AND UNCONDITIONALLY WAIVES, ANY AND
ALL RIGHT TO TRIAL BY JURY IN ANY ACTION, CASE, PROCEEDING, SUIT OR COUNTERCLAIM
ARISING IN CONNECTION WITH, OUT OF OR OTHERWISE RELATING TO THE CREDIT FACILITY,
THIS NOTE, OR THE OTHER CREDIT FACILITY DOCUMENTS.
<PAGE>

            XVIII. Whenever used, the singular number shall include the plural,
the plural the singular, and the words "Payee", "Agent", "Co-Lenders", and
"Maker" shall include their respective successors and assigns, provided,
however, that Maker shall in no event or under any circumstance have the right
without obtaining the prior written consent of Co-Lenders to assign or transfer
its obligations under this Note or the other Credit Facility Documents, in whole
or in part, to any other person, party or entity.

            XIX. No recourse shall be had for any obligation of BRT under this
Note or any of the other Credit Facility Documents or for any claim based
thereon or otherwise in respect thereof, against any past, present or future
trustee, shareholder, officer or employee of BRT, 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 Payee and
each other party to this Note and the other Credit Facility Documents.

            XX. Maker acknowledges and agrees that without limiting, modifying
or otherwise affecting in any respect the provisions of paragraph 25 of the
Credit Agreement, that (i) Payee shall have the sole obligation and
responsibility to fund its Credit Facility Percentage Interest (as set forth on
the Co-Lenders Certificate (the "Co-Lenders Certificate") being delivered to
Maker contemporaneously with the execution and delivery of this Note) in each
advance of the Credit Facility which is made, or required to be made, by
Co-Lenders in accordance with the provisions of the Credit Agreement and (ii)
Maker shall not have the right under any fact or circumstance to look to any
party other than Payee, including without limitation, Initial Co-Lenders or any
other Co-Lender, for the funding of the portion of the Credit Facility required
to be funded by Payee in accordance with the Credit Agreement and as set forth
in the Co-Lenders Certificate, if Payee shall default in doing so, all risk of
such loss being directly assumed in all respects by Maker.

            XXI. This Note is being executed and delivered in connection with an
increase in the Credit Facility from up to $80,000,000 to up to $150,000,000 and
this Note amends and restates in its entirety that certain Note dated as of
April 9, 1997 from Maker to Payee (the "Existing Note") but is not in payment,
satisfaction or cancellation of the outstanding indebtedness evidenced by the
Existing Note. Neither this Note nor any of the other Credit Facility Notes
dated the date hereof nor anything contained herein or therein shall be
construed as a substitution or novation of the indebtedness of Maker by the
Existing Note, which indebtedness (as so increased) shall remain in full force
and effect and is now evidenced by this Note and the other Credit Facility
Notes.
<PAGE>

            IN WITNESS WHEREOF, Maker has duly executed this Note the day and
year first above written.

                                   BRANDYWINE REALTY TRUST


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

                                   BRANDYWINE OPERATING PARTNERSHIP, L.P.

                                   By:  Brandywine Realty Trust, a Maryland 
                                        real estate investment trust, its 
                                        general partner


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

                                   LC/N HORSHAM LIMITED PARTNERSHIP, a 
                                   Pennsylvania limited partnership

                                   By:  Witmer Operating Partnership I, 
                                        L.P., a Delaware limited 
                                        partnership, its general partner

                                          By:  Brandywine Holdings I, Inc., a
                                               Pennsylvania corporation, its
                                               general partner


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

                                   LC/N KEITH VALLEY LIMITED PARTNERSHIP I, a
                                   Pennsylvania limited partnership
<PAGE>

                                   By:  Witmer Operating Partnership I, 
                                        L.P., a Delaware limited 
                                        partnership, its general partner

                                        By:  Brandywine Holdings I, Inc., a
                                             Pennsylvania corporation, its
                                             general partner


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

                                   NICHOLS LANSDALE LIMITED PARTNERSHIP III, 
                                   a Pennsylvania limited partnership

                                   By:  Witmer Operating Partnership I, 
                                        L.P., a Delaware limited 
                                        partnership, its general partner

                                        By:  Brandywine Holdings I, Inc., a
                                             Pennsylvania corporation, its
                                             general partner


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

                                   NEWTECH III LIMITED PARTNERSHIP, a 
                                   Pennsylvania limited partnership

                                   By:  Witmer Operating Partnership I, 
                                        L.P., a Delaware limited 
                                        partnership, its general partner

                                        By:  Brandywine Holdings I, Inc., a
                                             Pennsylvania corporation, its
                                             general partner


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

                                   NEWTECH IV LIMITED PARTNERSHIP, a 
                                   Pennsylvania limited partnership
<PAGE>

                                   By:  Witmer Operating Partnership I, 
                                        L.P., a Delaware limited 
                                        partnership, its general partner

                                        By:  Brandywine Holdings I, Inc., a
                                             Pennsylvania corporation, its
                                             general partner


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

                                   C/N OAKLANDS LIMITED PARTNERSHIP I, a
                                   Pennsylvania limited partnership

                                   By:  Witmer Operating Partnership I, 
                                        L.P., a Delaware limited 
                                        partnership, its general partner

                                        By:   Brandywine Holdings I, Inc., a
                                              Pennsylvania corporation, its
                                              general partner


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

                                   FIFTEEN HORSHAM, L.P., a Pennsylvania 
                                   limited partnership

                                   By:  Witmer Operating Partnership I, 
                                        L.P., a Delaware limited 
                                        partnership, its general partner

                                        By:  Brandywine Holdings I, Inc., a
                                             Pennsylvania corporation, its
                                             general partner


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

                                   C/N LEEDOM LIMITED PARTNERSHIP II, a 
                                   Pennsylvania limited partnership
<PAGE>

                                   By:  Brandywine Operating Partnership, 
                                        L.P., a Delaware limited 
                                        partnership, its general partner

                                        By:  Brandywine Realty Trust, a 
                                             Maryland real estate 
                                             investment trust, its general 
                                             partner


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

                                   C/N IRON RUN LIMITED PARTNERSHIP III, a 
                                   Pennsylvania limited partnership

                                   By:  Brandywine Operating Partnership, L.P.,
                                        a Delaware limited partnership, its 
                                        general partner

                                        By:  Brandywine Realty Trust, a Maryland
                                             real estate investment trust, its 
                                             general partner


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

                                   BRANDYWINE - MAIN STREET, LLC, a Delaware 
                                   limited liability company

                                   By:  Brandywine Operating Partnership, L.P., 
                                        a Delaware limited partnership, a member

                                        By:  Brandywine Realty Trust, a Maryland
                                             real estate investment trust, its 
                                             general partner


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

                                   By:  Brandywine Acquisitions, LLC, a Delaware
                                        limited liability company, a member
<PAGE>

                                        By:  Brandywine Operating Partnership, 
                                             L.P., a Delaware limited 
                                             partnership, a member

                                             By:  Brandywine Realty Trust, a 
                                                  Maryland real estate 
                                                  investment trust, its general 
                                                  partner


                                                  By:  /s/ Gerard H. Sweeney
                                                       -------------------------
                                                       Name:  Gerard H. Sweeney

                                                       Title: President
<PAGE>

                                   Exhibit D-2

AMENDED AND RESTATED NOTE
                           (Revolving Credit Facility)

$27,500,000.00                                                New York, New York
                                                             As of July 15, 1997

            FOR VALUE RECEIVED, Brandywine Realty Trust, a Maryland real estate
investment trust, Brandywine Operating Partnership, L.P., a Delaware limited
partnership, LC/N Horsham Limited Partnership, a Pennsylvania limited
partnership; LC/N Keith Valley Limited Partnership I, a Pennsylvania limited
partnership; Nichols Lansdale Limited Partnership III, a Pennsylvania limited
partnership; Newtech III Limited Partnership, a Pennsylvania limited
partnership; Newtech IV Limited Partnership, a Pennsylvania limited partnership;
C/N Oaklands Limited Partnership I, a Pennsylvania limited partnership; Fifteen
Horsham, L.P., a Pennsylvania limited partnership; C/N Leedom Limited
Partnership II, a Pennsylvania limited partnership; C/N Iron Run Limited
Partnership III, a Pennsylvania limited partnership; Brandywine-Main Street,
LLC, a Delaware limited liability company, each having an office at Newtown
Square Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
Pennsylvania (hereinafter collectively referred to as "Maker"), promise to pay
Smith Barney Mortgage Capital Group, Inc., a Delaware corporation having an
office at 390 Greenwich Street, New York, New York (hereinafter referred to as
"Payee") or order, at such place as may be designated from time to time in
writing by Payee, the principal sum of Twenty-Seven Million Five Hundred
Thousand and 00/100 Dollars ($27,500,000.00) in lawful money of the United
States of America, or so much thereof as may be advanced and readvanced by Payee
to Maker and be outstanding from time to time in accordance with the provisions
of the Credit Agreement, with interest thereon from and including the date of
this Note to, but not including, the date this Note is paid in full, calculated
in the manner hereinafter set forth, as follows:

                  1. interest on the Principal Balance calculated in the manner
      set forth in the Credit Agreement shall be due and payable in Federal
      funds or other immediately available funds on each Re-Set Date during the
      term of this Note and otherwise in accordance with the provisions of the
      Credit Agreement; and

                  2. the entire Principal Balance, together with all interest
      accrued and unpaid thereon calculated in the manner set forth in the
      Credit Agreement and all other sums due under this Note, shall be due and
      payable on the Maturity Date and otherwise in accordance with the
      provisions of the Credit Agreement.
<PAGE>

            XXII. The term "Credit Agreement" as used in this Note means a
certain Revolving Credit Agreement dated as of November 25, 1996 entered into
among Smith Barney Mortgage Capital Group, Inc., NationsBank, N.A., in its
individual capacity, Maker and NationsBank, N.A., acting in its capacity as
administrative and documentation agent for the Credit Facility, as the same may
be modified or amended from time to time, and pursuant to the provisions of
which the Credit Facility has been extended by Co-Lenders to Maker. This Note
constitutes one of the Credit Facility Notes which have been executed and
delivered by Maker to Co-Lenders in accordance with the Credit Agreement and
which together evidence the Credit Facility. All other capitalized terms used in
this Note shall, unless otherwise defined in this Note, have the meaning given
to such term in the Credit Agreement.

            XXIII. It is hereby expressly agreed that the entire Debt shall
become immediately due and payable at the option of Co-Lenders on the happening
of any Event of Default.

            XXIV. All of the terms, covenants and provisions contained in the
Credit Agreement and the other Credit Facility Documents which are to be kept
and performed by Maker are hereby made part of this Note to the same extent and
with the same force and effect as if they were fully set forth herein. Maker
agrees to perform and comply with each of the terms, covenants and provisions
contained in this Note, the Credit Agreement and the other Credit Facility
Documents on the part of Maker to be observed and performed.

            XXV. If any installment of interest payable under this Note is not
paid when due, Maker shall pay to Agent upon demand an amount equal to four
percent (4%) of such unpaid installment as a late payment charge.

            XXVI. In addition to any late payment charge which may be due under
this Note, if the Debt is declared immediately due and payable pursuant to the
provisions of the Credit Facility Documents, or if the Debt is not paid in full
on the Maturity Date, Maker shall thereafter pay interest on the then entire
outstanding Principal Balance from the date of such declaration or the Maturity
Date, as the case may be, until the date the Principal Balance is paid in full,
at the Default Rate. In addition, if an Event of Default shall occur, the
Principal Balance shall, from and including the date upon which such Event of
Default has occurred and for so long as such Event of Default continues and
without further act or instrument and without the necessity of any further or
prior notice by Payee or Agent to Maker, bear interest at the Default Rate
irrespective of whether the Debt shall have been declared to be immediately due
and payable as the result of the occurrence of such Event of Default.

            XXVII. Maker hereby waives presentment and demand for payment,
notice of dishonor, protest and notice of protest of this Note. If any payment
under this Note is not made when due, Maker agrees to pay all costs of
collection when incurred, including reasonable attorneys' fees (which costs
shall be added to the amount due under this Note and shall be receivable
therewith). No release of any security for the payment of this Note or extension
of time for payment of this Note, or any installment hereof, and no alteration,
amendment or waiver of any provision of this Note or any of the 
<PAGE>

other Credit Facility Documents made by agreement between or among Co-Lenders,
Agent and/or Payee and any other person or party shall release, discharge,
modify, change or affect the liability of Maker under this Note or any of the
other Credit Facility Documents.

            XXVIII. This Note is subject to the express condition that at no
time shall Maker be obligated or required to pay interest on the Principal
Balance at a rate which could subject Payee to either civil or criminal
liability as a result of being in excess of the maximum rate which Maker is
permitted by law to contract or agree to pay. If by the terms of this Note Maker
is at any time required or obligated to pay interest on the Principal Balance at
a rate in excess of such maximum rate, the rate of interest under this Note
shall be deemed to be immediately reduced to such maximum rate and interest
payable hereunder shall be computed at such maximum rate and the portion of all
prior interest payments in excess of such maximum rate shall be applied and
shall be deemed to have been payments in reduction of the Principal Balance.

            XXIX. If Maker consists of more than one person or party, the
obligations and liabilities of each such person or party hereunder shall be
joint and several.

            XXX. Except as otherwise specifically provided to the contrary in
the Credit Facility Documents, this Note is secured on a pari passu basis with
the other Credit Facility Notes by the Mortgages and the other Credit Facility
Documents.

            XXXI. The terms of this Note shall be governed by and construed
under the laws of the State of New York.

            XXXII. This Note may only be modified, amended, changed or
terminated by an agreement in writing signed by Payee, Agent and Maker. No
waiver of any term, covenant or provision of this Note shall be effective unless
given in writing by Payee and Agent and if so given by Payee and Agent shall
only be effective in the specific instance in which given.

            XXXIII. Maker acknowledges that this Note and Maker's obligations
under this Note are and shall at all times continue to be absolute and
unconditional in all respects, and shall at all times be valid and enforceable
irrespective of any other agreements or circumstances of any nature whatsoever
which might otherwise constitute a defense (other than a defense of payment) to
this Note and the obligations of Maker under this Note or the obligations of any
other person or party relating to this Note or the obligations of Maker
hereunder or otherwise with respect to the Credit Facility. Maker absolutely,
unconditionally and irrevocably waives any and all right to assert any defense,
setoff, counterclaim (other than a compulsory counterclaim in a court of
competent jurisdiction) or crossclaim of any nature whatsoever with respect to
this Note or the obligations of Maker under this Note or the obligations of any
other person or party relating to this Note or the obligations of Maker
hereunder or otherwise with respect to the Credit Facility in any action, case
or proceeding brought by Payee or Agent to collect the Debt, or any portion
<PAGE>

thereof, or to enforce, foreclose and realize upon the liens and security
interests created by the Mortgages and the other Credit Facility Documents
(provided, however, that the foregoing provisions of this sentence shall not be
deemed a waiver of the right of Maker to assert any compulsory counterclaim in
any such action, case or proceeding brought by Payee or Agent in any state court
if such counterclaim is compelled under local law or rule or procedure, or in
any such action, case or proceeding brought by Payee or Agent in a court of the
United States, nor shall the foregoing provisions of this sentence be deemed a
waiver of the right of Maker to assert any claim which would otherwise
constitute a defense, setoff, counterclaim or crossclaim of any nature
whatsoever against Payee or Agent in any separate action, case or proceeding
brought by Maker against Payee or Agent). MAKER ACKNOWLEDGES THAT NO ORAL OR
OTHER AGREEMENTS, UNDERSTANDINGS, REPRESENTATIONS OR WARRANTIES EXIST WITH
RESPECT TO THIS NOTE OR WITH RESPECT TO THE OBLIGATIONS OF MAKER UNDER THIS
NOTE, EXCEPT THOSE SPECIFICALLY SET FORTH IN THIS NOTE AND THE OTHER CREDIT
FACILITY DOCUMENTS, AND THAT THIS NOTE AND THE OTHER CREDIT FACILITY DOCUMENTS
SET FORTH THE ENTIRE AGREEMENT AND UNDERSTANDING OF PAYEE, AGENT, CO-LENDERS AND
MAKER.

            XXXIV. No delay on the part of Payee, Agent or Co-Lenders in
exercising any right or remedy under this Note or the other Credit Facility
Documents or failure to exercise the same shall operate as a waiver in whole or
in part of any such right or remedy. No notice to or demand on Maker shall be
deemed to be a waiver of the obligation of Maker or of the right of Payee, Agent
or Co-Lender to take further action without further notice or demand as provided
in this Note and the other Credit Facility Documents.

            XXXV. Maker agrees to submit to personal jurisdiction in the State
of New York in any action, case or proceeding arising out of this Note and, in
furtherance of such agreement, Maker hereby agrees and consents that without
limiting other methods of obtaining jurisdiction, personal jurisdiction over
Maker in any such action, case or proceeding may be obtained within or without
the jurisdiction of any court located in New York and that any process or notice
of motion or other application to any such court in connection with any such
action, case or proceeding may be served upon Maker by registered or certified
mail to or by personal service at the last known address of Maker, whether such
address be within or without the jurisdiction of any such court. Maker also
agrees that the venue of any litigation arising in connection with the Debt or
in respect of any of the obligations of Maker under this Note shall, to the
extent permitted by law, be in New York County.

            XXXVI. Maker (and the undersigned representative of Maker, if any)
represents that Maker has full power, authority and legal right to execute and
deliver this Note and that this Note constitutes a valid and binding obligation
of Maker.

            XXXVII. MAKER HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES, AND
PAYEE BY ITS ACCEPTANCE OF THIS NOTE IRREVOCABLY AND UNCONDITIONALLY WAIVES, ANY
AND ALL RIGHT TO TRIAL BY JURY IN ANY ACTION, CASE, PROCEEDING, SUIT OR
COUNTERCLAIM ARISING IN CONNECTION WITH, OUT OF OR OTHERWISE RELATING TO THE
CREDIT FACILITY, THIS NOTE, OR THE OTHER CREDIT FACILITY DOCUMENTS.
<PAGE>

            XXXVIII. Whenever used, the singular number shall include the
plural, the plural the singular, and the words "Payee", "Agent", "Co-Lenders",
and "Maker" shall include their respective successors and assigns, provided,
however, that Maker shall in no event or under any circumstance have the right
without obtaining the prior written consent of Co-Lenders to assign or transfer
its obligations under this Note or the other Credit Facility Documents, in whole
or in part, to any other person, party or entity.

            XXXIX. No recourse shall be had for any obligation of BRT under this
Note or any of the other Credit Facility Documents or for any claim based
thereon or otherwise in respect thereof, against any past, present or future
trustee, shareholder, officer or employee of BRT, 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 Payee and
each other party to this Note and the other Credit Facility Documents.

            XL. Maker acknowledges and agrees that without limiting, modifying
or otherwise affecting in any respect the provisions of paragraph 25 of the
Credit Agreement, that (i) Payee shall have the sole obligation and
responsibility to fund its Credit Facility Percentage Interest (as set forth on
the Co-Lenders Certificate (the "Co-Lenders Certificate") being delivered to
Maker contemporaneously with the execution and delivery of this Note) in each
advance of the Credit Facility which is made, or required to be made, by
Co-Lenders in accordance with the provisions of the Credit Agreement and (ii)
Maker shall not have the right under any fact or circumstance to look to any
party other than Payee, including without limitation, Initial Co-Lenders or any
other Co-Lender, for the funding of the portion of the Credit Facility required
to be funded by Payee in accordance with the Credit Agreement and as set forth
in the Co-Lenders Certificate, if Payee shall default in doing so, all risk of
such loss being directly assumed in all respects by Maker.

            XLI. This Note is being executed and delivered in connection with an
increase in the Credit Facility from up to $80,000,000 to up to $150,000,000 and
this Note amends and restates in its entirety that certain Note dated as of
April 9, 1997 from Maker to Payee (the "Existing Note") but is not in payment,
satisfaction or cancellation of the outstanding indebtedness evidenced by the
Existing Note. Neither this Note nor any of the other Credit Facility Notes
dated the date hereof nor anything contained herein or therein shall be
construed as a substitution or novation of the indebtedness of Maker by the
Existing Note, which indebtedness (as so increased) shall remain in full force
and effect and is now evidenced by this Note and the other Credit Facility
Notes.
<PAGE>

            IN WITNESS WHEREOF, Maker has duly executed this Note the day and
year first above written.

                                    BRANDYWINE REALTY TRUST


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

                                    BRANDYWINE OPERATING PARTNERSHIP, L.P.

                                    By:   Brandywine Realty Trust, a Maryland 
                                          real estate investment trust, its 
                                          general partner


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

                                    LC/N HORSHAM LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    LC/N KEITH VALLEY LIMITED PARTNERSHIP I, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NICHOLS LANSDALE LIMITED PARTNERSHIP III, 
                                    a Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NEWTECH III LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NEWTECH IV LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    C/N OAKLANDS LIMITED PARTNERSHIP I, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    FIFTEEN HORSHAM, L.P., a Pennsylvania 
                                    limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    C/N LEEDOM LIMITED PARTNERSHIP II, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    C/N IRON RUN LIMITED PARTNERSHIP III, a 
                                    Pennsylvania limited partnership

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    BRANDYWINE - MAIN STREET, LLC, a Delaware 
                                    limited liability company

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          a member

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    By:   Brandywine Acquisitions, LLC, a 
                                          Delaware limited liability company, 
                                          a member
<PAGE>

                                          By:   Brandywine Operating 
                                                Partnership, L.P., a Delaware
                                                limited partnership, a member

                                                By:   Brandywine Realty Trust, 
                                                      a Maryland real estate 
                                                      investment trust, its 
                                                      general partner


                                                     By:  /s/ Gerard H. Sweeney
                                                        -----------------------
                                                        Name:  Gerard H. Sweeney
                                                        Title: President and
                                                               Chief Executive
                                                               Officer
<PAGE>

                                   Exhibit D-3

                            AMENDED AND RESTATED NOTE
                           (Revolving Credit Facility)

$20,000,000.00                                                New York, New York
                                                             As of July 15, 1997

            FOR VALUE RECEIVED, Brandywine Realty Trust, a Maryland real estate
investment trust, Brandywine Operating Partnership, L.P., a Delaware limited
partnership, LC/N Horsham Limited Partnership, a Pennsylvania limited
partnership; LC/N Keith Valley Limited Partnership I, a Pennsylvania limited
partnership; Nichols Lansdale Limited Partnership III, a Pennsylvania limited
partnership; Newtech III Limited Partnership, a Pennsylvania limited
partnership; Newtech IV Limited Partnership, a Pennsylvania limited partnership;
C/N Oaklands Limited Partnership I, a Pennsylvania limited partnership; Fifteen
Horsham, L.P., a Pennsylvania limited partnership; C/N Leedom Limited
Partnership II, a Pennsylvania limited partnership; C/N Iron Run Limited
Partnership III, a Pennsylvania limited partnership; Brandywine-Main Street,
LLC, a Delaware limited liability company, each having an office at Newtown
Square Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
Pennsylvania (hereinafter collectively referred to as "Maker"), promise to pay
The First National Bank of Chicago, a national banking association having an
office at One First National Plaza, Chicago, Illinois (hereinafter referred to
as "Payee") or order, at such place as may be designated from time to time in
writing by Payee, the principal sum of Twenty Million and 00/100 Dollars
($20,000,000.00) in lawful money of the United States of America, or so much
thereof as may be advanced and readvanced by Payee to Maker and be outstanding
from time to time in accordance with the provisions of the Credit Agreement,
with interest thereon from and including the date of this Note to, but not
including, the date this Note is paid in full, calculated in the manner
hereinafter set forth, as follows:

                  1. interest on the Principal Balance calculated in the manner
      set forth in the Credit Agreement shall be due and payable in Federal
      funds or other immediately available funds on each Re-Set Date during the
      term of this Note and otherwise in accordance with the provisions of the
      Credit Agreement; and

                  2. the entire Principal Balance, together with all interest
      accrued and unpaid thereon calculated in the manner set forth in the
      Credit Agreement and all other sums due under this Note, shall be due and
      payable on the Maturity Date and otherwise in accordance with the
      provisions of the Credit Agreement.
<PAGE>

            XLII. The term "Credit Agreement" as used in this Note means a
certain Revolving Credit Agreement dated as of November 25, 1996 entered into
among Smith Barney Mortgage Capital Group, Inc., NationsBank, N.A., in its
individual capacity, Maker and NationsBank, N.A., acting in its capacity as
administrative and documentation agent for the Credit Facility, as the same may
be modified or amended from time to time, and pursuant to the provisions of
which the Credit Facility has been extended by Co-Lenders to Maker. This Note
constitutes one of the Credit Facility Notes which have been executed and
delivered by Maker to Co-Lenders in accordance with the Credit Agreement and
which together evidence the Credit Facility. All other capitalized terms used in
this Note shall, unless otherwise defined in this Note, have the meaning given
to such term in the Credit Agreement.

            XLIII. It is hereby expressly agreed that the entire Debt shall
become immediately due and payable at the option of Co-Lenders on the happening
of any Event of Default.

            XLIV. All of the terms, covenants and provisions contained in the
Credit Agreement and the other Credit Facility Documents which are to be kept
and performed by Maker are hereby made part of this Note to the same extent and
with the same force and effect as if they were fully set forth herein. Maker
agrees to perform and comply with each of the terms, covenants and provisions
contained in this Note, the Credit Agreement and the other Credit Facility
Documents on the part of Maker to be observed and performed.

            XLV. If any installment of interest payable under this Note is not
paid when due, Maker shall pay to Agent upon demand an amount equal to four
percent (4%) of such unpaid installment as a late payment charge.

            XLVI. In addition to any late payment charge which may be due under
this Note, if the Debt is declared immediately due and payable pursuant to the
provisions of the Credit Facility Documents, or if the Debt is not paid in full
on the Maturity Date, Maker shall thereafter pay interest on the then entire
outstanding Principal Balance from the date of such declaration or the Maturity
Date, as the case may be, until the date the Principal Balance is paid in full,
at the Default Rate. In addition, if an Event of Default shall occur, the
Principal Balance shall, from and including the date upon which such Event of
Default has occurred and for so long as such Event of Default continues and
without further act or instrument and without the necessity of any further or
prior notice by Payee or Agent to Maker, bear interest at the Default Rate
irrespective of whether the Debt shall have been declared to be immediately due
and payable as the result of the occurrence of such Event of Default.

            XLVII. Maker hereby waives presentment and demand for payment,
notice of dishonor, protest and notice of protest of this Note. If any payment
under this Note is not made when due, Maker agrees to pay all costs of
collection when incurred, including reasonable attorneys' fees (which costs
shall be added to the amount due under this Note and shall be receivable
therewith). No release of any security for the payment of this Note or extension
of time for payment of this Note, or any installment hereof, and no alteration,
amendment or waiver of any provision of this Note or any of the 
<PAGE>

other Credit Facility Documents made by agreement between or among Co-Lenders,
Agent and/or Payee and any other person or party shall release, discharge,
modify, change or affect the liability of Maker under this Note or any of the
other Credit Facility Documents.

            XLVIII. This Note is subject to the express condition that at no
time shall Maker be obligated or required to pay interest on the Principal
Balance at a rate which could subject Payee to either civil or criminal
liability as a result of being in excess of the maximum rate which Maker is
permitted by law to contract or agree to pay. If by the terms of this Note Maker
is at any time required or obligated to pay interest on the Principal Balance at
a rate in excess of such maximum rate, the rate of interest under this Note
shall be deemed to be immediately reduced to such maximum rate and interest
payable hereunder shall be computed at such maximum rate and the portion of all
prior interest payments in excess of such maximum rate shall be applied and
shall be deemed to have been payments in reduction of the Principal Balance.

            XLIX. If Maker consists of more than one person or party, the
obligations and liabilities of each such person or party hereunder shall be
joint and several.

            L. Except as otherwise specifically provided to the contrary in the
Credit Facility Documents, this Note is secured on a pari passu basis with the
other Credit Facility Notes by the Mortgages and the other Credit Facility
Documents.

            LI. The terms of this Note shall be governed by and construed under
the laws of the State of New York.

            LII. This Note may only be modified, amended, changed or terminated
by an agreement in writing signed by Payee, Agent and Maker. No waiver of any
term, covenant or provision of this Note shall be effective unless given in
writing by Payee and Agent and if so given by Payee and Agent shall only be
effective in the specific instance in which given.

            LIII. Maker acknowledges that this Note and Maker's obligations
under this Note are and shall at all times continue to be absolute and
unconditional in all respects, and shall at all times be valid and enforceable
irrespective of any other agreements or circumstances of any nature whatsoever
which might otherwise constitute a defense (other than a defense of payment) to
this Note and the obligations of Maker under this Note or the obligations of any
other person or party relating to this Note or the obligations of Maker
hereunder or otherwise with respect to the Credit Facility. Maker absolutely,
unconditionally and irrevocably waives any and all right to assert any defense,
setoff, counterclaim (other than a compulsory counterclaim in a court of
competent jurisdiction) or crossclaim of any nature whatsoever with respect to
this Note or the obligations of Maker under this Note or the obligations of any
other person or party relating to this Note or the obligations of Maker
hereunder or otherwise with respect to the Credit Facility in any action, case
or proceeding brought by Payee or Agent to collect the Debt, or any portion
<PAGE>

thereof, or to enforce, foreclose and realize upon the liens and security
interests created by the Mortgages and the other Credit Facility Documents
(provided, however, that the foregoing provisions of this sentence shall not be
deemed a waiver of the right of Maker to assert any compulsory counterclaim in
any such action, case or proceeding brought by Payee or Agent in any state court
if such counterclaim is compelled under local law or rule or procedure, or in
any such action, case or proceeding brought by Payee or Agent in a court of the
United States, nor shall the foregoing provisions of this sentence be deemed a
waiver of the right of Maker to assert any claim which would otherwise
constitute a defense, setoff, counterclaim or crossclaim of any nature
whatsoever against Payee or Agent in any separate action, case or proceeding
brought by Maker against Payee or Agent). MAKER ACKNOWLEDGES THAT NO ORAL OR
OTHER AGREEMENTS, UNDERSTANDINGS, REPRESENTATIONS OR WARRANTIES EXIST WITH
RESPECT TO THIS NOTE OR WITH RESPECT TO THE OBLIGATIONS OF MAKER UNDER THIS
NOTE, EXCEPT THOSE SPECIFICALLY SET FORTH IN THIS NOTE AND THE OTHER CREDIT
FACILITY DOCUMENTS, AND THAT THIS NOTE AND THE OTHER CREDIT FACILITY DOCUMENTS
SET FORTH THE ENTIRE AGREEMENT AND UNDERSTANDING OF PAYEE, AGENT, CO-LENDERS AND
MAKER.

            LIV. No delay on the part of Payee, Agent or Co-Lenders in
exercising any right or remedy under this Note or the other Credit Facility
Documents or failure to exercise the same shall operate as a waiver in whole or
in part of any such right or remedy. No notice to or demand on Maker shall be
deemed to be a waiver of the obligation of Maker or of the right of Payee, Agent
or Co-Lender to take further action without further notice or demand as provided
in this Note and the other Credit Facility Documents.

            LV. Maker agrees to submit to personal jurisdiction in the State of
New York in any action, case or proceeding arising out of this Note and, in
furtherance of such agreement, Maker hereby agrees and consents that without
limiting other methods of obtaining jurisdiction, personal jurisdiction over
Maker in any such action, case or proceeding may be obtained within or without
the jurisdiction of any court located in New York and that any process or notice
of motion or other application to any such court in connection with any such
action, case or proceeding may be served upon Maker by registered or certified
mail to or by personal service at the last known address of Maker, whether such
address be within or without the jurisdiction of any such court. Maker also
agrees that the venue of any litigation arising in connection with the Debt or
in respect of any of the obligations of Maker under this Note shall, to the
extent permitted by law, be in New York County.

            LVI. Maker (and the undersigned representative of Maker, if any)
represents that Maker has full power, authority and legal right to execute and
deliver this Note and that this Note constitutes a valid and binding obligation
of Maker.

            LVII. MAKER HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES, AND PAYEE
BY ITS ACCEPTANCE OF THIS NOTE IRREVOCABLY AND UNCONDITIONALLY WAIVES, ANY AND
ALL RIGHT TO TRIAL BY JURY IN ANY ACTION, CASE, PROCEEDING, SUIT OR COUNTERCLAIM
ARISING IN CONNECTION WITH, OUT OF OR OTHERWISE RELATING TO THE CREDIT FACILITY,
THIS NOTE, OR THE OTHER CREDIT FACILITY DOCUMENTS.
<PAGE>

            LVIII. Whenever used, the singular number shall include the plural,
the plural the singular, and the words "Payee", "Agent", "Co-Lenders", and
"Maker" shall include their respective successors and assigns, provided,
however, that Maker shall in no event or under any circumstance have the right
without obtaining the prior written consent of Co-Lenders to assign or transfer
its obligations under this Note or the other Credit Facility Documents, in whole
or in part, to any other person, party or entity.

            LIX. No recourse shall be had for any obligation of BRT under this
Note or any of the other Credit Facility Documents or for any claim based
thereon or otherwise in respect thereof, against any past, present or future
trustee, shareholder, officer or employee of BRT, 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 Payee and
each other party to this Note and the other Credit Facility Documents.

            LX. Maker acknowledges and agrees that without limiting, modifying
or otherwise affecting in any respect the provisions of paragraph 25 of the
Credit Agreement, that (i) Payee shall have the sole obligation and
responsibility to fund its Credit Facility Percentage Interest (as set forth on
the Co-Lenders Certificate (the "Co-Lenders Certificate") being delivered to
Maker contemporaneously with the execution and delivery of this Note) in each
advance of the Credit Facility which is made, or required to be made, by
Co-Lenders in accordance with the provisions of the Credit Agreement and (ii)
Maker shall not have the right under any fact or circumstance to look to any
party other than Payee, including without limitation, Initial Co-Lenders or any
other Co-Lender, for the funding of the portion of the Credit Facility required
to be funded by Payee in accordance with the Credit Agreement and as set forth
in the Co-Lenders Certificate, if Payee shall default in doing so, all risk of
such loss being directly assumed in all respects by Maker.

            LXI. This Note is being executed and delivered in connection with an
increase in the Credit Facility from up to $80,000,000 to up to $150,000,000 and
this Note amends and restates in its entirety that certain Note dated as of
April 9, 1997 from Maker to Payee (the "Existing Note") but is not in payment,
satisfaction or cancellation of the outstanding indebtedness evidenced by the
Existing Note. Neither this Note nor any of the other Credit Facility Notes
dated the date hereof nor anything contained herein or therein shall be
construed as a substitution or novation of the indebtedness of Maker by the
Existing Note, which indebtedness (as so increased) shall remain in full force
and effect and is now evidenced by this Note and the other Credit Facility
Notes.
<PAGE>

            IN WITNESS WHEREOF, Maker has duly executed this Note the day and
year first above written.

                                    BRANDYWINE REALTY TRUST


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

                                    BRANDYWINE OPERATING PARTNERSHIP, L.P.

                                    By:   Brandywine Realty Trust, a Maryland 
                                          real estate investment trust, its 
                                          general partner


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

                                    LC/N HORSHAM LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    LC/N KEITH VALLEY LIMITED PARTNERSHIP I, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NICHOLS LANSDALE LIMITED PARTNERSHIP III, 
                                    a Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NEWTECH III LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NEWTECH IV LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    C/N OAKLANDS LIMITED PARTNERSHIP I, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    FIFTEEN HORSHAM, L.P., a Pennsylvania 
                                    limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    C/N LEEDOM LIMITED PARTNERSHIP II, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    C/N IRON RUN LIMITED PARTNERSHIP III, a 
                                    Pennsylvania limited partnership

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    BRANDYWINE - MAIN STREET, LLC, a Delaware 
                                    limited liability company

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          a member

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    By:   Brandywine Acquisitions, LLC, a 
                                          Delaware limited liability company, 
                                          a member
<PAGE>

                                          By:   Brandywine Operating 
                                                Partnership, L.P., a Delaware
                                                limited partnership, a member

                                                By:   Brandywine Realty Trust, 
                                                      a Maryland real estate 
                                                      investment trust, its 
                                                      general partner


                                                     By:  /s/ Gerard H. Sweeney
                                                        -----------------------
                                                        Name:  Gerard H. Sweeney
                                                        Title: President and
                                                               Chief Executive
                                                               Officer
<PAGE>

                                   Exhibit D-4

                            AMENDED AND RESTATED NOTE
                           (Revolving Credit Facility)

$20,000,000.00                                                New York, New York
                                                             As of July 15, 1997

            FOR VALUE RECEIVED, Brandywine Realty Trust, a Maryland real estate
investment trust, Brandywine Operating Partnership, L.P., a Delaware limited
partnership, LC/N Horsham Limited Partnership, a Pennsylvania limited
partnership; LC/N Keith Valley Limited Partnership I, a Pennsylvania limited
partnership; Nichols Lansdale Limited Partnership III, a Pennsylvania limited
partnership; Newtech III Limited Partnership, a Pennsylvania limited
partnership; Newtech IV Limited Partnership, a Pennsylvania limited partnership;
C/N Oaklands Limited Partnership I, a Pennsylvania limited partnership; Fifteen
Horsham, L.P., a Pennsylvania limited partnership; C/N Leedom Limited
Partnership II, a Pennsylvania limited partnership; C/N Iron Run Limited
Partnership III, a Pennsylvania limited partnership; Brandywine-Main Street,
LLC, a Delaware limited liability company, each having an office at Newtown
Square Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
Pennsylvania (hereinafter collectively referred to as "Maker"), promise to pay
Mellon Bank, N.A. a national banking association having an office at 1735 Market
Street, Philadelphia, Pennsylvania (hereinafter referred to as "Payee") or
order, at such place as may be designated from time to time in writing by Payee,
the principal sum of Twenty Million and 00/100 Dollars ($20,000,000.00) in
lawful money of the United States of America, or so much thereof as may be
advanced and readvanced by Payee to Maker and be outstanding from time to time
in accordance with the provisions of the Credit Agreement, with interest thereon
from and including the date of this Note to, but not including, the date this
Note is paid in full, calculated in the manner hereinafter set forth, as
follows:

                  1. interest on the Principal Balance calculated in the manner
      set forth in the Credit Agreement shall be due and payable in Federal
      funds or other immediately available funds on each Re-Set Date during the
      term of this Note and otherwise in accordance with the provisions of the
      Credit Agreement; and

                  2. the entire Principal Balance, together with all interest
      accrued and unpaid thereon calculated in the manner set forth in the
      Credit Agreement and all other sums due under this Note, shall be due and
      payable on the Maturity Date and otherwise in accordance with the
      provisions of the Credit Agreement.
<PAGE>

            LXII. The term "Credit Agreement" as used in this Note means a
certain Revolving Credit Agreement dated as of November 25, 1996 entered into
among Smith Barney Mortgage Capital Group, Inc., NationsBank, N.A., in its
individual capacity, Maker and NationsBank, N.A., acting in its capacity as
administrative and documentation agent for the Credit Facility, as the same may
be modified or amended from time to time, and pursuant to the provisions of
which the Credit Facility has been extended by Co-Lenders to Maker. This Note
constitutes one of the Credit Facility Notes which have been executed and
delivered by Maker to Co-Lenders in accordance with the Credit Agreement and
which together evidence the Credit Facility. All other capitalized terms used in
this Note shall, unless otherwise defined in this Note, have the meaning given
to such term in the Credit Agreement.

            LXIII. It is hereby expressly agreed that the entire Debt shall
become immediately due and payable at the option of Co-Lenders on the happening
of any Event of Default.

            LXIV. All of the terms, covenants and provisions contained in the
Credit Agreement and the other Credit Facility Documents which are to be kept
and performed by Maker are hereby made part of this Note to the same extent and
with the same force and effect as if they were fully set forth herein. Maker
agrees to perform and comply with each of the terms, covenants and provisions
contained in this Note, the Credit Agreement and the other Credit Facility
Documents on the part of Maker to be observed and performed.

            LXV. If any installment of interest payable under this Note is not
paid when due, Maker shall pay to Agent upon demand an amount equal to four
percent (4%) of such unpaid installment as a late payment charge.

            LXVI. In addition to any late payment charge which may be due under
this Note, if the Debt is declared immediately due and payable pursuant to the
provisions of the Credit Facility Documents, or if the Debt is not paid in full
on the Maturity Date, Maker shall thereafter pay interest on the then entire
outstanding Principal Balance from the date of such declaration or the Maturity
Date, as the case may be, until the date the Principal Balance is paid in full,
at the Default Rate. In addition, if an Event of Default shall occur, the
Principal Balance shall, from and including the date upon which such Event of
Default has occurred and for so long as such Event of Default continues and
without further act or instrument and without the necessity of any further or
prior notice by Payee or Agent to Maker, bear interest at the Default Rate
irrespective of whether the Debt shall have been declared to be immediately due
and payable as the result of the occurrence of such Event of Default.

            LXVII. Maker hereby waives presentment and demand for payment,
notice of dishonor, protest and notice of protest of this Note. If any payment
under this Note is not made when due, Maker agrees to pay all costs of
collection when incurred, including reasonable attorneys' fees (which costs
shall be added to the amount due under this Note and shall be receivable
therewith). No release of any security for the payment of this Note or extension
of time for payment of this Note, or any installment hereof, and no alteration,
amendment or waiver of any provision of this Note or any of the 
<PAGE>

other Credit Facility Documents made by agreement between or among Co-Lenders,
Agent and/or Payee and any other person or party shall release, discharge,
modify, change or affect the liability of Maker under this Note or any of the
other Credit Facility Documents.

            LXVIII. This Note is subject to the express condition that at no
time shall Maker be obligated or required to pay interest on the Principal
Balance at a rate which could subject Payee to either civil or criminal
liability as a result of being in excess of the maximum rate which Maker is
permitted by law to contract or agree to pay. If by the terms of this Note Maker
is at any time required or obligated to pay interest on the Principal Balance at
a rate in excess of such maximum rate, the rate of interest under this Note
shall be deemed to be immediately reduced to such maximum rate and interest
payable hereunder shall be computed at such maximum rate and the portion of all
prior interest payments in excess of such maximum rate shall be applied and
shall be deemed to have been payments in reduction of the Principal Balance.

            LXIX. If Maker consists of more than one person or party, the
obligations and liabilities of each such person or party hereunder shall be
joint and several.

            LXX. Except as otherwise specifically provided to the contrary in
the Credit Facility Documents, this Note is secured on a pari passu basis with
the other Credit Facility Notes by the Mortgages and the other Credit Facility
Documents.

            LXXI. The terms of this Note shall be governed by and construed
under the laws of the State of New York.

            LXXII. This Note may only be modified, amended, changed or
terminated by an agreement in writing signed by Payee, Agent and Maker. No
waiver of any term, covenant or provision of this Note shall be effective unless
given in writing by Payee and Agent and if so given by Payee and Agent shall
only be effective in the specific instance in which given.

            LXXIII. Maker acknowledges that this Note and Maker's obligations
under this Note are and shall at all times continue to be absolute and
unconditional in all respects, and shall at all times be valid and enforceable
irrespective of any other agreements or circumstances of any nature whatsoever
which might otherwise constitute a defense (other than a defense of payment) to
this Note and the obligations of Maker under this Note or the obligations of any
other person or party relating to this Note or the obligations of Maker
hereunder or otherwise with respect to the Credit Facility. Maker absolutely,
unconditionally and irrevocably waives any and all right to assert any defense,
setoff, counterclaim (other than a compulsory counterclaim in a court of
competent jurisdiction) or crossclaim of any nature whatsoever with respect to
this Note or the obligations of Maker under this Note or the obligations of any
other person or party relating to this Note or the obligations of Maker
hereunder or otherwise with respect to the Credit Facility in any action, case
or proceeding brought by Payee or Agent to collect the Debt, or any portion
<PAGE>

thereof, or to enforce, foreclose and realize upon the liens and security
interests created by the Mortgages and the other Credit Facility Documents
(provided, however, that the foregoing provisions of this sentence shall not be
deemed a waiver of the right of Maker to assert any compulsory counterclaim in
any such action, case or proceeding brought by Payee or Agent in any state court
if such counterclaim is compelled under local law or rule or procedure, or in
any such action, case or proceeding brought by Payee or Agent in a court of the
United States, nor shall the foregoing provisions of this sentence be deemed a
waiver of the right of Maker to assert any claim which would otherwise
constitute a defense, setoff, counterclaim or crossclaim of any nature
whatsoever against Payee or Agent in any separate action, case or proceeding
brought by Maker against Payee or Agent). MAKER ACKNOWLEDGES THAT NO ORAL OR
OTHER AGREEMENTS, UNDERSTANDINGS, REPRESENTATIONS OR WARRANTIES EXIST WITH
RESPECT TO THIS NOTE OR WITH RESPECT TO THE OBLIGATIONS OF MAKER UNDER THIS
NOTE, EXCEPT THOSE SPECIFICALLY SET FORTH IN THIS NOTE AND THE OTHER CREDIT
FACILITY DOCUMENTS, AND THAT THIS NOTE AND THE OTHER CREDIT FACILITY DOCUMENTS
SET FORTH THE ENTIRE AGREEMENT AND UNDERSTANDING OF PAYEE, AGENT, CO-LENDERS AND
MAKER.

            LXXIV. No delay on the part of Payee, Agent or Co-Lenders in
exercising any right or remedy under this Note or the other Credit Facility
Documents or failure to exercise the same shall operate as a waiver in whole or
in part of any such right or remedy. No notice to or demand on Maker shall be
deemed to be a waiver of the obligation of Maker or of the right of Payee, Agent
or Co-Lender to take further action without further notice or demand as provided
in this Note and the other Credit Facility Documents.

            LXXV. Maker agrees to submit to personal jurisdiction in the State
of New York in any action, case or proceeding arising out of this Note and, in
furtherance of such agreement, Maker hereby agrees and consents that without
limiting other methods of obtaining jurisdiction, personal jurisdiction over
Maker in any such action, case or proceeding may be obtained within or without
the jurisdiction of any court located in New York and that any process or notice
of motion or other application to any such court in connection with any such
action, case or proceeding may be served upon Maker by registered or certified
mail to or by personal service at the last known address of Maker, whether such
address be within or without the jurisdiction of any such court. Maker also
agrees that the venue of any litigation arising in connection with the Debt or
in respect of any of the obligations of Maker under this Note shall, to the
extent permitted by law, be in New York County.

            LXXVI. Maker (and the undersigned representative of Maker, if any)
represents that Maker has full power, authority and legal right to execute and
deliver this Note and that this Note constitutes a valid and binding obligation
of Maker.

            LXXVII. MAKER HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES, AND
PAYEE BY ITS ACCEPTANCE OF THIS NOTE IRREVOCABLY AND UNCONDITIONALLY WAIVES, ANY
AND ALL RIGHT TO TRIAL BY JURY IN ANY ACTION, CASE, PROCEEDING, SUIT OR
COUNTERCLAIM ARISING IN CONNECTION WITH, OUT OF OR OTHERWISE RELATING TO THE
CREDIT FACILITY, THIS NOTE, OR THE OTHER CREDIT FACILITY DOCUMENTS.
<PAGE>

            LXXVIII. Whenever used, the singular number shall include the
plural, the plural the singular, and the words "Payee", "Agent", "Co-Lenders",
and "Maker" shall include their respective successors and assigns, provided,
however, that Maker shall in no event or under any circumstance have the right
without obtaining the prior written consent of Co-Lenders to assign or transfer
its obligations under this Note or the other Credit Facility Documents, in whole
or in part, to any other person, party or entity.

            LXXIX. No recourse shall be had for any obligation of BRT under this
Note or any of the other Credit Facility Documents or for any claim based
thereon or otherwise in respect thereof, against any past, present or future
trustee, shareholder, officer or employee of BRT, 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 Payee and
each other party to this Note and the other Credit Facility Documents.

            LXXX. Maker acknowledges and agrees that without limiting, modifying
or otherwise affecting in any respect the provisions of paragraph 25 of the
Credit Agreement, that (i) Payee shall have the sole obligation and
responsibility to fund its Credit Facility Percentage Interest (as set forth on
the Co-Lenders Certificate (the "Co-Lenders Certificate") being delivered to
Maker contemporaneously with the execution and delivery of this Note) in each
advance of the Credit Facility which is made, or required to be made, by
Co-Lenders in accordance with the provisions of the Credit Agreement and (ii)
Maker shall not have the right under any fact or circumstance to look to any
party other than Payee, including without limitation, Initial Co-Lenders or any
other Co-Lender, for the funding of the portion of the Credit Facility required
to be funded by Payee in accordance with the Credit Agreement and as set forth
in the Co-Lenders Certificate, if Payee shall default in doing so, all risk of
such loss being directly assumed in all respects by Maker.

            LXXXI. This Note is being executed and delivered in connection with
an increase in the Credit Facility from up to $80,000,000 to up to $150,000,000
and this Note amends and restates in its entirety that certain Note dated as of
April 4, 1997 from Maker to Payee (the "Existing Note") but is not in payment,
satisfaction or cancellation of the outstanding indebtedness evidenced by the
Existing Note. Neither this Note nor any of the other Credit Facility Notes
dated the date hereof nor anything contained herein or therein shall be
construed as a substitution or novation of the indebtedness of Maker by the
Existing Note, which indebtedness (as so increased) shall remain in full force
and effect and is now evidenced by this Note and the other Credit Facility
Notes.
<PAGE>

            IN WITNESS WHEREOF, Maker has duly executed this Note the day and
year first above written.

                                    BRANDYWINE REALTY TRUST


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

                                    BRANDYWINE OPERATING PARTNERSHIP, L.P.

                                    By:   Brandywine Realty Trust, a Maryland 
                                          real estate investment trust, its 
                                          general partner


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

                                    LC/N HORSHAM LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    LC/N KEITH VALLEY LIMITED PARTNERSHIP I, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NICHOLS LANSDALE LIMITED PARTNERSHIP III, 
                                    a Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NEWTECH III LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NEWTECH IV LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    C/N OAKLANDS LIMITED PARTNERSHIP I, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    FIFTEEN HORSHAM, L.P., a Pennsylvania 
                                    limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    C/N LEEDOM LIMITED PARTNERSHIP II, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    C/N IRON RUN LIMITED PARTNERSHIP III, a 
                                    Pennsylvania limited partnership

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    BRANDYWINE - MAIN STREET, LLC, a Delaware 
                                    limited liability company

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          a member

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    By:   Brandywine Acquisitions, LLC, a 
                                          Delaware limited liability company, 
                                          a member
<PAGE>

                                          By:   Brandywine Operating 
                                                Partnership, L.P., a Delaware
                                                limited partnership, a member

                                                By:   Brandywine Realty Trust, 
                                                      a Maryland real estate 
                                                      investment trust, its 
                                                      general partner


                                                     By:  /s/ Gerard H. Sweeney
                                                        -----------------------
                                                        Name:  Gerard H. Sweeney
                                                        Title: President and
                                                               Chief Executive
                                                               Officer
<PAGE>

                                   Exhibit D-5

                            AMENDED AND RESTATED NOTE
                           (Revolving Credit Facility)

$20,000,000.00                                                New York, New York
                                                             As of July 15, 1997

            FOR VALUE RECEIVED, Brandywine Realty Trust, a Maryland real estate
investment trust, Brandywine Operating Partnership, L.P., a Delaware limited
partnership, LC/N Horsham Limited Partnership, a Pennsylvania limited
partnership; LC/N Keith Valley Limited Partnership I, a Pennsylvania limited
partnership; Nichols Lansdale Limited Partnership III, a Pennsylvania limited
partnership; Newtech III Limited Partnership, a Pennsylvania limited
partnership; Newtech IV Limited Partnership, a Pennsylvania limited partnership;
C/N Oaklands Limited Partnership I, a Pennsylvania limited partnership; Fifteen
Horsham, L.P., a Pennsylvania limited partnership; C/N Leedom Limited
Partnership II, a Pennsylvania limited partnership; C/N Iron Run Limited
Partnership III, a Pennsylvania limited partnership; Brandywine-Main Street,
LLC, a Delaware limited liability company, each having an office at Newtown
Square Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
Pennsylvania (hereinafter collectively referred to as "Maker"), promise to pay
PNC Bank, National Association, a national banking association having an office
at 1600 Market Street, Philadelphia, Pennsylvania (hereinafter referred to as
"Payee") or order, at such place as may be designated from time to time in
writing by Payee, the principal sum of Twenty Million and 00/100 Dollars
($20,000,000.00) in lawful money of the United States of America, or so much
thereof as may be advanced and readvanced by Payee to Maker and be outstanding
from time to time in accordance with the provisions of the Credit Agreement,
with interest thereon from and including the date of this Note to, but not
including, the date this Note is paid in full, calculated in the manner
hereinafter set forth, as follows:

                  1. interest on the Principal Balance calculated in the manner
      set forth in the Credit Agreement shall be due and payable in Federal
      funds or other immediately available funds on each Re-Set Date during the
      term of this Note and otherwise in accordance with the provisions of the
      Credit Agreement; and

                  2. the entire Principal Balance, together with all interest
      accrued and unpaid thereon calculated in the manner set forth in the
      Credit Agreement and all other sums due under this Note, shall be due and
      payable on the Maturity Date and otherwise in accordance with the
      provisions of the Credit Agreement.
<PAGE>

            LXXXII. The term "Credit Agreement" as used in this Note means a
certain Revolving Credit Agreement dated as of November 25, 1996 entered into
among Smith Barney Mortgage Capital Group, Inc., NationsBank, N.A., in its
individual capacity, Maker and NationsBank, N.A., acting in its capacity as
administrative and documentation agent for the Credit Facility, as the same may
be modified or amended from time to time, and pursuant to the provisions of
which the Credit Facility has been extended by Co-Lenders to Maker. This Note
constitutes one of the Credit Facility Notes which have been executed and
delivered by Maker to Co-Lenders in accordance with the Credit Agreement and
which together evidence the Credit Facility. All other capitalized terms used in
this Note shall, unless otherwise defined in this Note, have the meaning given
to such term in the Credit Agreement.

            LXXXIII. It is hereby expressly agreed that the entire Debt shall
become immediately due and payable at the option of Co-Lenders on the happening
of any Event of Default.

            LXXXIV. All of the terms, covenants and provisions contained in the
Credit Agreement and the other Credit Facility Documents which are to be kept
and performed by Maker are hereby made part of this Note to the same extent and
with the same force and effect as if they were fully set forth herein. Maker
agrees to perform and comply with each of the terms, covenants and provisions
contained in this Note, the Credit Agreement and the other Credit Facility
Documents on the part of Maker to be observed and performed.

            LXXXV. If any installment of interest payable under this Note is not
paid when due, Maker shall pay to Agent upon demand an amount equal to four
percent (4%) of such unpaid installment as a late payment charge.

            LXXXVI. In addition to any late payment charge which may be due
under this Note, if the Debt is declared immediately due and payable pursuant to
the provisions of the Credit Facility Documents, or if the Debt is not paid in
full on the Maturity Date, Maker shall thereafter pay interest on the then
entire outstanding Principal Balance from the date of such declaration or the
Maturity Date, as the case may be, until the date the Principal Balance is paid
in full, at the Default Rate. In addition, if an Event of Default shall occur,
the Principal Balance shall, from and including the date upon which such Event
of Default has occurred and for so long as such Event of Default continues and
without further act or instrument and without the necessity of any further or
prior notice by Payee or Agent to Maker, bear interest at the Default Rate
irrespective of whether the Debt shall have been declared to be immediately due
and payable as the result of the occurrence of such Event of Default.

            LXXXVII. Maker hereby waives presentment and demand for payment,
notice of dishonor, protest and notice of protest of this Note. If any payment
under this Note is not made when due, Maker agrees to pay all costs of
collection when incurred, including reasonable attorneys' fees (which costs
shall be added to the amount due under this Note and shall be receivable
therewith). No release of any security for the payment of this Note or extension
of time for payment of this Note, or any installment hereof, and no alteration,
amendment or waiver of any provision of this Note or any of the other Credit
Facility Documents made by agreement between or among Co-Lenders, 
<PAGE>

Agent and/or Payee and any other person or party shall release, discharge,
modify, change or affect the liability of Maker under this Note or any of the
other Credit Facility Documents.

            LXXXVIII. This Note is subject to the express condition that at no
time shall Maker be obligated or required to pay interest on the Principal
Balance at a rate which could subject Payee to either civil or criminal
liability as a result of being in excess of the maximum rate which Maker is
permitted by law to contract or agree to pay. If by the terms of this Note Maker
is at any time required or obligated to pay interest on the Principal Balance at
a rate in excess of such maximum rate, the rate of interest under this Note
shall be deemed to be immediately reduced to such maximum rate and interest
payable hereunder shall be computed at such maximum rate and the portion of all
prior interest payments in excess of such maximum rate shall be applied and
shall be deemed to have been payments in reduction of the Principal Balance.

            LXXXIX. If Maker consists of more than one person or party, the
obligations and liabilities of each such person or party hereunder shall be
joint and several.

            XC. Except as otherwise specifically provided to the contrary in the
Credit Facility Documents, this Note is secured on a pari passu basis with the
other Credit Facility Notes by the Mortgages and the other Credit Facility
Documents.

            XCI. The terms of this Note shall be governed by and construed under
the laws of the State of New York.

            XCII. This Note may only be modified, amended, changed or terminated
by an agreement in writing signed by Payee, Agent and Maker. No waiver of any
term, covenant or provision of this Note shall be effective unless given in
writing by Payee and Agent and if so given by Payee and Agent shall only be
effective in the specific instance in which given.

            XCIII. Maker acknowledges that this Note and Maker's obligations
under this Note are and shall at all times continue to be absolute and
unconditional in all respects, and shall at all times be valid and enforceable
irrespective of any other agreements or circumstances of any nature whatsoever
which might otherwise constitute a defense (other than a defense of payment) to
this Note and the obligations of Maker under this Note or the obligations of any
other person or party relating to this Note or the obligations of Maker
hereunder or otherwise with respect to the Credit Facility. Maker absolutely,
unconditionally and irrevocably waives any and all right to assert any defense,
setoff, counterclaim (other than a compulsory counterclaim in a court of
competent jurisdiction) or crossclaim of any nature whatsoever with respect to
this Note or the obligations of Maker under this Note or the obligations of any
other person or party relating to this Note or the obligations of Maker
hereunder or otherwise with respect to the Credit Facility in any action, case
or proceeding brought by Payee or Agent to collect the Debt, or any portion
thereof, or to enforce, foreclose and realize upon the liens and security
<PAGE>

interests created by the Mortgages and the other Credit Facility Documents
(provided, however, that the foregoing provisions of this sentence shall not be
deemed a waiver of the right of Maker to assert any compulsory counterclaim in
any such action, case or proceeding brought by Payee or Agent in any state court
if such counterclaim is compelled under local law or rule or procedure, or in
any such action, case or proceeding brought by Payee or Agent in a court of the
United States, nor shall the foregoing provisions of this sentence be deemed a
waiver of the right of Maker to assert any claim which would otherwise
constitute a defense, setoff, counterclaim or crossclaim of any nature
whatsoever against Payee or Agent in any separate action, case or proceeding
brought by Maker against Payee or Agent). MAKER ACKNOWLEDGES THAT NO ORAL OR
OTHER AGREEMENTS, UNDERSTANDINGS, REPRESENTATIONS OR WARRANTIES EXIST WITH
RESPECT TO THIS NOTE OR WITH RESPECT TO THE OBLIGATIONS OF MAKER UNDER THIS
NOTE, EXCEPT THOSE SPECIFICALLY SET FORTH IN THIS NOTE AND THE OTHER CREDIT
FACILITY DOCUMENTS, AND THAT THIS NOTE AND THE OTHER CREDIT FACILITY DOCUMENTS
SET FORTH THE ENTIRE AGREEMENT AND UNDERSTANDING OF PAYEE, AGENT, CO-LENDERS AND
MAKER.

            XCIV. No delay on the part of Payee, Agent or Co-Lenders in
exercising any right or remedy under this Note or the other Credit Facility
Documents or failure to exercise the same shall operate as a waiver in whole or
in part of any such right or remedy. No notice to or demand on Maker shall be
deemed to be a waiver of the obligation of Maker or of the right of Payee, Agent
or Co-Lender to take further action without further notice or demand as provided
in this Note and the other Credit Facility Documents.

            XCV. Maker agrees to submit to personal jurisdiction in the State of
New York in any action, case or proceeding arising out of this Note and, in
furtherance of such agreement, Maker hereby agrees and consents that without
limiting other methods of obtaining jurisdiction, personal jurisdiction over
Maker in any such action, case or proceeding may be obtained within or without
the jurisdiction of any court located in New York and that any process or notice
of motion or other application to any such court in connection with any such
action, case or proceeding may be served upon Maker by registered or certified
mail to or by personal service at the last known address of Maker, whether such
address be within or without the jurisdiction of any such court. Maker also
agrees that the venue of any litigation arising in connection with the Debt or
in respect of any of the obligations of Maker under this Note shall, to the
extent permitted by law, be in New York County.

            XCVI. Maker (and the undersigned representative of Maker, if any)
represents that Maker has full power, authority and legal right to execute and
deliver this Note and that this Note constitutes a valid and binding obligation
of Maker.

            XCVII. MAKER HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES, AND
PAYEE BY ITS ACCEPTANCE OF THIS NOTE IRREVOCABLY AND UNCONDITIONALLY WAIVES, ANY
AND ALL RIGHT TO TRIAL BY JURY IN ANY ACTION, CASE, PROCEEDING, SUIT OR
COUNTERCLAIM ARISING IN CONNECTION WITH, OUT OF OR OTHERWISE RELATING TO THE
CREDIT FACILITY, THIS NOTE, OR THE OTHER CREDIT FACILITY DOCUMENTS.
<PAGE>

            XCVIII. Whenever used, the singular number shall include the plural,
the plural the singular, and the words "Payee", "Agent", "Co-Lenders", and
"Maker" shall include their respective successors and assigns, provided,
however, that Maker shall in no event or under any circumstance have the right
without obtaining the prior written consent of Co-Lenders to assign or transfer
its obligations under this Note or the other Credit Facility Documents, in whole
or in part, to any other person, party or entity.

            XCIX. No recourse shall be had for any obligation of BRT under this
Note or any of the other Credit Facility Documents or for any claim based
thereon or otherwise in respect thereof, against any past, present or future
trustee, shareholder, officer or employee of BRT, 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 Payee and
each other party to this Note and the other Credit Facility Documents.

            C. Maker acknowledges and agrees that without limiting, modifying or
otherwise affecting in any respect the provisions of paragraph 25 of the Credit
Agreement, that (i) Payee shall have the sole obligation and responsibility to
fund its Credit Facility Percentage Interest (as set forth on the Co-Lenders
Certificate (the "Co-Lenders Certificate") being delivered to Maker
contemporaneously with the execution and delivery of this Note) in each advance
of the Credit Facility which is made, or required to be made, by Co-Lenders in
accordance with the provisions of the Credit Agreement and (ii) Maker shall not
have the right under any fact or circumstance to look to any party other than
Payee, including without limitation, Initial Co-Lenders or any other Co-Lender,
for the funding of the portion of the Credit Facility required to be funded by
Payee in accordance with the Credit Agreement and as set forth in the Co-Lenders
Certificate, if Payee shall default in doing so, all risk of such loss being
directly assumed in all respects by Maker.

            CI. This Note is being executed and delivered in connection with an
increase in the Credit Facility from up to $80,000,000 to up to $150,000,000 and
this Note amends and restates in its entirety that certain Note dated as of
April 4, 1997 from Maker to Payee (the "Existing Note") but is not in payment,
satisfaction or cancellation of the outstanding indebtedness evidenced by the
Existing Note. Neither this Note nor any of the other Credit Facility Notes
dated the date hereof nor anything contained herein or therein shall be
construed as a substitution or novation of the indebtedness of Maker by the
Existing Note, which indebtedness (as so increased) shall remain in full force
and effect and is now evidenced by this Note and the other Credit Facility
Notes.
<PAGE>

            IN WITNESS WHEREOF, Maker has duly executed this Note the day and
year first above written.

                                    BRANDYWINE REALTY TRUST


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

                                    BRANDYWINE OPERATING PARTNERSHIP, L.P.

                                    By:   Brandywine Realty Trust, a Maryland 
                                          real estate investment trust, its 
                                          general partner


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

                                    LC/N HORSHAM LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    LC/N KEITH VALLEY LIMITED PARTNERSHIP I, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NICHOLS LANSDALE LIMITED PARTNERSHIP III, 
                                    a Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NEWTECH III LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NEWTECH IV LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    C/N OAKLANDS LIMITED PARTNERSHIP I, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    FIFTEEN HORSHAM, L.P., a Pennsylvania 
                                    limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    C/N LEEDOM LIMITED PARTNERSHIP II, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    C/N IRON RUN LIMITED PARTNERSHIP III, a 
                                    Pennsylvania limited partnership

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    BRANDYWINE - MAIN STREET, LLC, a Delaware 
                                    limited liability company

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          a member

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    By:   Brandywine Acquisitions, LLC, a 
                                          Delaware limited liability company, 
                                          a member
<PAGE>

                                          By:   Brandywine Operating 
                                                Partnership, L.P., a Delaware
                                                limited partnership, a member

                                                By:   Brandywine Realty Trust, 
                                                      a Maryland real estate 
                                                      investment trust, its 
                                                      general partner


                                                     By:  /s/ Gerard H. Sweeney
                                                        -----------------------
                                                        Name:  Gerard H. Sweeney
                                                        Title: President and
                                                               Chief Executive
                                                               Officer
<PAGE>

                                   Exhibit D-6

                            AMENDED AND RESTATED NOTE
                           (Revolving Credit Facility)

$15,000,000.00                                                New York, New York
                                                             As of July 15, 1997

            FOR VALUE RECEIVED, Brandywine Realty Trust, a Maryland real estate
investment trust, Brandywine Operating Partnership, L.P., a Delaware limited
partnership, LC/N Horsham Limited Partnership, a Pennsylvania limited
partnership; LC/N Keith Valley Limited Partnership I, a Pennsylvania limited
partnership; Nichols Lansdale Limited Partnership III, a Pennsylvania limited
partnership; Newtech III Limited Partnership, a Pennsylvania limited
partnership; Newtech IV Limited Partnership, a Pennsylvania limited partnership;
C/N Oaklands Limited Partnership I, a Pennsylvania limited partnership; Fifteen
Horsham, L.P., a Pennsylvania limited partnership; C/N Leedom Limited
Partnership II, a Pennsylvania limited partnership; C/N Iron Run Limited
Partnership III, a Pennsylvania limited partnership; Brandywine-Main Street,
LLC, a Delaware limited liability company, each having an office at Newtown
Square Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
Pennsylvania (hereinafter collectively referred to as "Maker"), promise to pay
Signet Bank, a state banking association organized under the laws of the
Commonwealth of Virginia having an office at 7779 Leesburg Pike, 4th Floor,
Falls Church, Virginia (hereinafter referred to as "Payee") or order, at such
place as may be designated from time to time in writing by Payee, the principal
sum of Fifteen Million and 00/100 Dollars ($15,000,000.00) in lawful money of
the United States of America, or so much thereof as may be advanced and
readvanced by Payee to Maker and be outstanding from time to time in accordance
with the provisions of the Credit Agreement, with interest thereon from and
including the date of this Note to, but not including, the date this Note is
paid in full, calculated in the manner hereinafter set forth, as follows:

                  1. interest on the Principal Balance calculated in the manner
      set forth in the Credit Agreement shall be due and payable in Federal
      funds or other immediately available funds on each Re-Set Date during the
      term of this Note and otherwise in accordance with the provisions of the
      Credit Agreement; and

                  2. the entire Principal Balance, together with all interest
      accrued and unpaid thereon calculated in the manner set forth in the
      Credit Agreement and all other sums due under this Note, shall be due and
      payable on the Maturity Date and otherwise in accordance with the
      provisions of the Credit Agreement.
<PAGE>

            CII. The term "Credit Agreement" as used in this Note means a
certain Revolving Credit Agreement dated as of November 25, 1996 entered into
among Smith Barney Mortgage Capital Group, Inc., NationsBank, N.A., in its
individual capacity, Maker and NationsBank, N.A., acting in its capacity as
administrative and documentation agent for the Credit Facility, as the same may
be modified or amended from time to time, and pursuant to the provisions of
which the Credit Facility has been extended by Co-Lenders to Maker. This Note
constitutes one of the Credit Facility Notes which have been executed and
delivered by Maker to Co-Lenders in accordance with the Credit Agreement and
which together evidence the Credit Facility. All other capitalized terms used in
this Note shall, unless otherwise defined in this Note, have the meaning given
to such term in the Credit Agreement.

            CIII. It is hereby expressly agreed that the entire Debt shall
become immediately due and payable at the option of Co-Lenders on the happening
of any Event of Default.

            CIV. All of the terms, covenants and provisions contained in the
Credit Agreement and the other Credit Facility Documents which are to be kept
and performed by Maker are hereby made part of this Note to the same extent and
with the same force and effect as if they were fully set forth herein. Maker
agrees to perform and comply with each of the terms, covenants and provisions
contained in this Note, the Credit Agreement and the other Credit Facility
Documents on the part of Maker to be observed and performed.

            CV. If any installment of interest payable under this Note is not
paid when due, Maker shall pay to Agent upon demand an amount equal to four
percent (4%) of such unpaid installment as a late payment charge.

            CVI. In addition to any late payment charge which may be due under
this Note, if the Debt is declared immediately due and payable pursuant to the
provisions of the Credit Facility Documents, or if the Debt is not paid in full
on the Maturity Date, Maker shall thereafter pay interest on the then entire
outstanding Principal Balance from the date of such declaration or the Maturity
Date, as the case may be, until the date the Principal Balance is paid in full,
at the Default Rate. In addition, if an Event of Default shall occur, the
Principal Balance shall, from and including the date upon which such Event of
Default has occurred and for so long as such Event of Default continues and
without further act or instrument and without the necessity of any further or
prior notice by Payee or Agent to Maker, bear interest at the Default Rate
irrespective of whether the Debt shall have been declared to be immediately due
and payable as the result of the occurrence of such Event of Default.

            CVII. Maker hereby waives presentment and demand for payment, notice
of dishonor, protest and notice of protest of this Note. If any payment under
this Note is not made when due, Maker agrees to pay all costs of collection when
incurred, including reasonable attorneys' fees (which costs shall be added to
the amount due under this Note and shall be receivable therewith). No release of
any security for the payment of this Note or extension of time for payment of
this Note, or any installment hereof, and no 
<PAGE>

alteration, amendment or waiver of any provision of this Note or any of the
other Credit Facility Documents made by agreement between or among Co-Lenders,
Agent and/or Payee and any other person or party shall release, discharge,
modify, change or affect the liability of Maker under this Note or any of the
other Credit Facility Documents.

            CVIII. This Note is subject to the express condition that at no time
shall Maker be obligated or required to pay interest on the Principal Balance at
a rate which could subject Payee to either civil or criminal liability as a
result of being in excess of the maximum rate which Maker is permitted by law to
contract or agree to pay. If by the terms of this Note Maker is at any time
required or obligated to pay interest on the Principal Balance at a rate in
excess of such maximum rate, the rate of interest under this Note shall be
deemed to be immediately reduced to such maximum rate and interest payable
hereunder shall be computed at such maximum rate and the portion of all prior
interest payments in excess of such maximum rate shall be applied and shall be
deemed to have been payments in reduction of the Principal Balance.

            CIX. If Maker consists of more than one person or party, the
obligations and liabilities of each such person or party hereunder shall be
joint and several.

            CX. Except as otherwise specifically provided to the contrary in the
Credit Facility Documents, this Note is secured on a pari passu basis with the
other Credit Facility Notes by the Mortgages and the other Credit Facility
Documents.

            CXI. The terms of this Note shall be governed by and construed under
the laws of the State of New York.

            CXII. This Note may only be modified, amended, changed or terminated
by an agreement in writing signed by Payee, Agent and Maker. No waiver of any
term, covenant or provision of this Note shall be effective unless given in
writing by Payee and Agent and if so given by Payee and Agent shall only be
effective in the specific instance in which given.

            CXIII. Maker acknowledges that this Note and Maker's obligations
under this Note are and shall at all times continue to be absolute and
unconditional in all respects, and shall at all times be valid and enforceable
irrespective of any other agreements or circumstances of any nature whatsoever
which might otherwise constitute a defense (other than a defense of payment) to
this Note and the obligations of Maker under this Note or the obligations of any
other person or party relating to this Note or the obligations of Maker
hereunder or otherwise with respect to the Credit Facility. Maker absolutely,
unconditionally and irrevocably waives any and all right to assert any defense,
setoff, counterclaim (other than a compulsory counterclaim in a court of
competent jurisdiction) or crossclaim of any nature whatsoever with respect to
this Note or the obligations of Maker under this Note or the obligations of any
other person or party relating to this Note or the obligations of Maker
hereunder or otherwise with respect to the Credit Facility in any action, case
or proceeding brought by Payee or Agent to collect the Debt, or any portion
thereof, or to enforce, foreclose and realize upon the liens and security
interests created by the Mortgages and the other Credit Facility Documents
(provided, however, that the foregoing provisions of this sentence shall not be
deemed a waiver of the right of Maker to assert any compulsory counterclaim in
any such action, case 
<PAGE>

or proceeding brought by Payee or Agent in any state court if such counterclaim
is compelled under local law or rule or procedure, or in any such action, case
or proceeding brought by Payee or Agent in a court of the United States, nor
shall the foregoing provisions of this sentence be deemed a waiver of the right
of Maker to assert any claim which would otherwise constitute a defense, setoff,
counterclaim or crossclaim of any nature whatsoever against Payee or Agent in
any separate action, case or proceeding brought by Maker against Payee or
Agent). MAKER ACKNOWLEDGES THAT NO ORAL OR OTHER AGREEMENTS, UNDERSTANDINGS,
REPRESENTATIONS OR WARRANTIES EXIST WITH RESPECT TO THIS NOTE OR WITH RESPECT TO
THE OBLIGATIONS OF MAKER UNDER THIS NOTE, EXCEPT THOSE SPECIFICALLY SET FORTH IN
THIS NOTE AND THE OTHER CREDIT FACILITY DOCUMENTS, AND THAT THIS NOTE AND THE
OTHER CREDIT FACILITY DOCUMENTS SET FORTH THE ENTIRE AGREEMENT AND UNDERSTANDING
OF PAYEE, AGENT, CO-LENDERS AND MAKER.

            CXIV. No delay on the part of Payee, Agent or Co-Lenders in
exercising any right or remedy under this Note or the other Credit Facility
Documents or failure to exercise the same shall operate as a waiver in whole or
in part of any such right or remedy. No notice to or demand on Maker shall be
deemed to be a waiver of the obligation of Maker or of the right of Payee, Agent
or Co-Lender to take further action without further notice or demand as provided
in this Note and the other Credit Facility Documents.

            CXV. Maker agrees to submit to personal jurisdiction in the State of
New York in any action, case or proceeding arising out of this Note and, in
furtherance of such agreement, Maker hereby agrees and consents that without
limiting other methods of obtaining jurisdiction, personal jurisdiction over
Maker in any such action, case or proceeding may be obtained within or without
the jurisdiction of any court located in New York and that any process or notice
of motion or other application to any such court in connection with any such
action, case or proceeding may be served upon Maker by registered or certified
mail to or by personal service at the last known address of Maker, whether such
address be within or without the jurisdiction of any such court. Maker also
agrees that the venue of any litigation arising in connection with the Debt or
in respect of any of the obligations of Maker under this Note shall, to the
extent permitted by law, be in New York County.

            CXVI. Maker (and the undersigned representative of Maker, if any)
represents that Maker has full power, authority and legal right to execute and
deliver this Note and that this Note constitutes a valid and binding obligation
of Maker.

            CXVII. MAKER HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES, AND
PAYEE BY ITS ACCEPTANCE OF THIS NOTE IRREVOCABLY AND UNCONDITIONALLY WAIVES, ANY
AND ALL RIGHT TO TRIAL BY JURY IN ANY ACTION, CASE, PROCEEDING, SUIT OR
<PAGE>

COUNTERCLAIM ARISING IN CONNECTION WITH, OUT OF OR OTHERWISE RELATING TO THE
CREDIT FACILITY, THIS NOTE, OR THE OTHER CREDIT FACILITY DOCUMENTS.

            CXVIII. Whenever used, the singular number shall include the plural,
the plural the singular, and the words "Payee", "Agent", "Co-Lenders", and
"Maker" shall include their respective successors and assigns, provided,
however, that Maker shall in no event or under any circumstance have the right
without obtaining the prior written consent of Co-Lenders to assign or transfer
its obligations under this Note or the other Credit Facility Documents, in whole
or in part, to any other person, party or entity.

            CXIX. No recourse shall be had for any obligation of BRT under this
Note or any of the other Credit Facility Documents or for any claim based
thereon or otherwise in respect thereof, against any past, present or future
trustee, shareholder, officer or employee of BRT, 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 Payee and
each other party to this Note and the other Credit Facility Documents.

            CXX. Maker acknowledges and agrees that without limiting, modifying
or otherwise affecting in any respect the provisions of paragraph 25 of the
Credit Agreement, that (i) Payee shall have the sole obligation and
responsibility to fund its Credit Facility Percentage Interest (as set forth on
the Co-Lenders Certificate (the "Co-Lenders Certificate") being delivered to
Maker contemporaneously with the execution and delivery of this Note) in each
advance of the Credit Facility which is made, or required to be made, by
Co-Lenders in accordance with the provisions of the Credit Agreement and (ii)
Maker shall not have the right under any fact or circumstance to look to any
party other than Payee, including without limitation, Initial Co-Lenders or any
other Co-Lender, for the funding of the portion of the Credit Facility required
to be funded by Payee in accordance with the Credit Agreement and as set forth
in the Co-Lenders Certificate, if Payee shall default in doing so, all risk of
such loss being directly assumed in all respects by Maker.

            CXXI. This Note is being executed and delivered in connection with
an increase in the Credit Facility from up to $80,000,000 to up to $150,000,000
and this Note amends and restates in its entirety that certain Note dated as of
April 4, 1997 from Maker to Payee (the "Existing Note") but is not in payment,
satisfaction or cancellation of the outstanding indebtedness evidenced by the
Existing Note. Neither this Note nor any of the other Credit Facility Notes
dated the date hereof nor anything contained herein or therein shall be
construed as a substitution or novation of the indebtedness of Maker by the
Existing Note, which indebtedness (as so increased) shall remain in full force
and effect and is now evidenced by this Note and the other Credit Facility
Notes.
<PAGE>

            IN WITNESS WHEREOF, Maker has duly executed this Note the day and
year first above written.

                                    BRANDYWINE REALTY TRUST


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

                                    BRANDYWINE OPERATING PARTNERSHIP, L.P.

                                    By:   Brandywine Realty Trust, a Maryland 
                                          real estate investment trust, its 
                                          general partner


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

                                    LC/N HORSHAM LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    LC/N KEITH VALLEY LIMITED PARTNERSHIP I, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NICHOLS LANSDALE LIMITED PARTNERSHIP III, 
                                    a Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NEWTECH III LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NEWTECH IV LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    C/N OAKLANDS LIMITED PARTNERSHIP I, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    FIFTEEN HORSHAM, L.P., a Pennsylvania 
                                    limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    C/N LEEDOM LIMITED PARTNERSHIP II, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    C/N IRON RUN LIMITED PARTNERSHIP III, a 
                                    Pennsylvania limited partnership

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    BRANDYWINE - MAIN STREET, LLC, a Delaware 
                                    limited liability company

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          a member

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    By:   Brandywine Acquisitions, LLC, a 
                                          Delaware limited liability company, 
                                          a member
<PAGE>

                                          By:   Brandywine Operating 
                                                Partnership, L.P., a Delaware
                                                limited partnership, a member

                                                By:   Brandywine Realty Trust, 
                                                      a Maryland real estate 
                                                      investment trust, its 
                                                      general partner


                                                     By:  /s/ Gerard H. Sweeney
                                                        -----------------------
                                                        Name:  Gerard H. Sweeney
                                                        Title: President
<PAGE>

                                   Exhibit D-7

                            AMENDED AND RESTATED NOTE
                           (Revolving Credit Facility)

$20,000,000.00                                                New York, New York
                                                             As of July 15, 1997

            FOR VALUE RECEIVED, Brandywine Realty Trust, a Maryland real estate
investment trust, Brandywine Operating Partnership, L.P., a Delaware limited
partnership, LC/N Horsham Limited Partnership, a Pennsylvania limited
partnership; LC/N Keith Valley Limited Partnership I, a Pennsylvania limited
partnership; Nichols Lansdale Limited Partnership III, a Pennsylvania limited
partnership; Newtech III Limited Partnership, a Pennsylvania limited
partnership; Newtech IV Limited Partnership, a Pennsylvania limited partnership;
C/N Oaklands Limited Partnership I, a Pennsylvania limited partnership; Fifteen
Horsham, L.P., a Pennsylvania limited partnership; C/N Leedom Limited
Partnership II, a Pennsylvania limited partnership; C/N Iron Run Limited
Partnership III, a Pennsylvania limited partnership; Brandywine-Main Street,
LLC, a Delaware limited liability company, each having an office at Newtown
Square Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
Pennsylvania (hereinafter collectively referred to as "Maker"), promise to pay
Summit Bank, a state banking association organized under the laws of the State
of New Jersey having an office at 1800 Chapel Avenue West, Cherry Hill, New
Jersey (hereinafter referred to as "Payee") or order, at such place as may be
designated from time to time in writing by Payee, the principal sum of Twenty
Million and 00/100 Dollars ($20,000,000.00) in lawful money of the United States
of America, or so much thereof as may be advanced and readvanced by Payee to
Maker and be outstanding from time to time in accordance with the provisions of
the Credit Agreement, with interest thereon from and including the date of this
Note to, but not including, the date this Note is paid in full, calculated in
the manner hereinafter set forth, as follows:

                  1. interest on the Principal Balance calculated in the manner
      set forth in the Credit Agreement shall be due and payable in Federal
      funds or other immediately available funds on each Re-Set Date during the
      term of this Note and otherwise in accordance with the provisions of the
      Credit Agreement; and

                  2. the entire Principal Balance, together with all interest
      accrued and unpaid thereon calculated in the manner set forth in the
      Credit Agreement and all other sums due under this Note, shall be due and
      payable on the Maturity Date and otherwise in accordance with the
      provisions of the Credit Agreement.
<PAGE>

            CXXII. The term "Credit Agreement" as used in this Note means a
certain Revolving Credit Agreement dated as of November 25, 1996 entered into
among Smith Barney Mortgage Capital Group, Inc., NationsBank, N.A., in its
individual capacity, Maker and NationsBank, N.A., acting in its capacity as
administrative and documentation agent for the Credit Facility, as the same may
be modified or amended from time to time, and pursuant to the provisions of
which the Credit Facility has been extended by Co-Lenders to Maker. This Note
constitutes one of the Credit Facility Notes which have been executed and
delivered by Maker to Co-Lenders in accordance with the Credit Agreement and
which together evidence the Credit Facility. All other capitalized terms used in
this Note shall, unless otherwise defined in this Note, have the meaning given
to such term in the Credit Agreement.

            CXXIII. It is hereby expressly agreed that the entire Debt shall
become immediately due and payable at the option of Co-Lenders on the happening
of any Event of Default.

            CXXIV. All of the terms, covenants and provisions contained in the
Credit Agreement and the other Credit Facility Documents which are to be kept
and performed by Maker are hereby made part of this Note to the same extent and
with the same force and effect as if they were fully set forth herein. Maker
agrees to perform and comply with each of the terms, covenants and provisions
contained in this Note, the Credit Agreement and the other Credit Facility
Documents on the part of Maker to be observed and performed.

            CXXV. If any installment of interest payable under this Note is not
paid when due, Maker shall pay to Agent upon demand an amount equal to four
percent (4%) of such unpaid installment as a late payment charge.

            CXXVI. In addition to any late payment charge which may be due under
this Note, if the Debt is declared immediately due and payable pursuant to the
provisions of the Credit Facility Documents, or if the Debt is not paid in full
on the Maturity Date, Maker shall thereafter pay interest on the then entire
outstanding Principal Balance from the date of such declaration or the Maturity
Date, as the case may be, until the date the Principal Balance is paid in full,
at the Default Rate. In addition, if an Event of Default shall occur, the
Principal Balance shall, from and including the date upon which such Event of
Default has occurred and for so long as such Event of Default continues and
without further act or instrument and without the necessity of any further or
prior notice by Payee or Agent to Maker, bear interest at the Default Rate
irrespective of whether the Debt shall have been declared to be immediately due
and payable as the result of the occurrence of such Event of Default.

            CXXVII. Maker hereby waives presentment and demand for payment,
notice of dishonor, protest and notice of protest of this Note. If any payment
under this Note is not made when due, Maker agrees to pay all costs of
collection when incurred, including reasonable attorneys' fees (which costs
shall be added to the amount due under this Note and shall be receivable
therewith). No release of any security for the payment of this Note or extension
of time for payment of this Note, or any installment hereof, and no alteration,
amendment or waiver of any provision of this Note or any of the other Credit
Facility Documents made by agreement between or among Co-Lenders, 
<PAGE>

Agent and/or Payee and any other person or party shall release, discharge,
modify, change or affect the liability of Maker under this Note or any of the
other Credit Facility Documents.

            CXXVIII. This Note is subject to the express condition that at no
time shall Maker be obligated or required to pay interest on the Principal
Balance at a rate which could subject Payee to either civil or criminal
liability as a result of being in excess of the maximum rate which Maker is
permitted by law to contract or agree to pay. If by the terms of this Note Maker
is at any time required or obligated to pay interest on the Principal Balance at
a rate in excess of such maximum rate, the rate of interest under this Note
shall be deemed to be immediately reduced to such maximum rate and interest
payable hereunder shall be computed at such maximum rate and the portion of all
prior interest payments in excess of such maximum rate shall be applied and
shall be deemed to have been payments in reduction of the Principal Balance.

            CXXIX. If Maker consists of more than one person or party, the
obligations and liabilities of each such person or party hereunder shall be
joint and several.

            CXXX. Except as otherwise specifically provided to the contrary in
the Credit Facility Documents, this Note is secured on a pari passu basis with
the other Credit Facility Notes by the Mortgages and the other Credit Facility
Documents.

            CXXXI. The terms of this Note shall be governed by and construed
under the laws of the State of New York.

            CXXXII. This Note may only be modified, amended, changed or
terminated by an agreement in writing signed by Payee, Agent and Maker. No
waiver of any term, covenant or provision of this Note shall be effective unless
given in writing by Payee and Agent and if so given by Payee and Agent shall
only be effective in the specific instance in which given.

            CXXXIII. Maker acknowledges that this Note and Maker's obligations
under this Note are and shall at all times continue to be absolute and
unconditional in all respects, and shall at all times be valid and enforceable
irrespective of any other agreements or circumstances of any nature whatsoever
which might otherwise constitute a defense (other than a defense of payment) to
this Note and the obligations of Maker under this Note or the obligations of any
other person or party relating to this Note or the obligations of Maker
hereunder or otherwise with respect to the Credit Facility. Maker absolutely,
unconditionally and irrevocably waives any and all right to assert any defense,
setoff, counterclaim (other than a compulsory counterclaim in a court of
competent jurisdiction) or crossclaim of any nature whatsoever with respect to
this Note or the obligations of Maker under this Note or the obligations of any
other person or party relating to this Note or the obligations of Maker
hereunder or otherwise with respect to the Credit Facility in any action, case
or proceeding brought by Payee or Agent to collect the Debt, or any portion
thereof, or to enforce, foreclose and realize upon the liens and security
interests created by the Mortgages and the other 
<PAGE>

Credit Facility Documents (provided, however, that the foregoing provisions of
this sentence shall not be deemed a waiver of the right of Maker to assert any
compulsory counterclaim in any such action, case or proceeding brought by Payee
or Agent in any state court if such counterclaim is compelled under local law or
rule or procedure, or in any such action, case or proceeding brought by Payee or
Agent in a court of the United States, nor shall the foregoing provisions of
this sentence be deemed a waiver of the right of Maker to assert any claim which
would otherwise constitute a defense, setoff, counterclaim or crossclaim of any
nature whatsoever against Payee or Agent in any separate action, case or
proceeding brought by Maker against Payee or Agent). MAKER ACKNOWLEDGES THAT NO
ORAL OR OTHER AGREEMENTS, UNDERSTANDINGS, REPRESENTATIONS OR WARRANTIES EXIST
WITH RESPECT TO THIS NOTE OR WITH RESPECT TO THE OBLIGATIONS OF MAKER UNDER THIS
NOTE, EXCEPT THOSE SPECIFICALLY SET FORTH IN THIS NOTE AND THE OTHER CREDIT
FACILITY DOCUMENTS, AND THAT THIS NOTE AND THE OTHER CREDIT FACILITY DOCUMENTS
SET FORTH THE ENTIRE AGREEMENT AND UNDERSTANDING OF PAYEE, AGENT, CO-LENDERS AND
MAKER.

            CXXXIV. No delay on the part of Payee, Agent or Co-Lenders in
exercising any right or remedy under this Note or the other Credit Facility
Documents or failure to exercise the same shall operate as a waiver in whole or
in part of any such right or remedy. No notice to or demand on Maker shall be
deemed to be a waiver of the obligation of Maker or of the right of Payee, Agent
or Co-Lender to take further action without further notice or demand as provided
in this Note and the other Credit Facility Documents.

            CXXXV. Maker agrees to submit to personal jurisdiction in the State
of New York in any action, case or proceeding arising out of this Note and, in
furtherance of such agreement, Maker hereby agrees and consents that without
limiting other methods of obtaining jurisdiction, personal jurisdiction over
Maker in any such action, case or proceeding may be obtained within or without
the jurisdiction of any court located in New York and that any process or notice
of motion or other application to any such court in connection with any such
action, case or proceeding may be served upon Maker by registered or certified
mail to or by personal service at the last known address of Maker, whether such
address be within or without the jurisdiction of any such court. Maker also
agrees that the venue of any litigation arising in connection with the Debt or
in respect of any of the obligations of Maker under this Note shall, to the
extent permitted by law, be in New York County.

            CXXXVI. Maker (and the undersigned representative of Maker, if any)
represents that Maker has full power, authority and legal right to execute and
deliver this Note and that this Note constitutes a valid and binding obligation
of Maker.

            CXXXVII. MAKER HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES, AND
PAYEE BY ITS ACCEPTANCE OF THIS NOTE IRREVOCABLY AND UNCONDITIONALLY WAIVES, ANY
AND ALL RIGHT TO TRIAL BY JURY IN ANY ACTION, CASE, PROCEEDING, SUIT OR
COUNTERCLAIM ARISING IN CONNECTION WITH, OUT OF OR OTHERWISE RELATING TO THE
CREDIT FACILITY, THIS NOTE, OR THE OTHER CREDIT FACILITY DOCUMENTS.

            CXXXVIII. Whenever used, the singular number shall include the
plural, the plural the singular, and the words "Payee", "Agent", "Co-Lenders",
<PAGE>

and "Maker" shall include their respective successors and assigns, provided,
however, that Maker shall in no event or under any circumstance have the right
without obtaining the prior written consent of Co-Lenders to assign or transfer
its obligations under this Note or the other Credit Facility Documents, in whole
or in part, to any other person, party or entity.

            CXXXIX. No recourse shall be had for any obligation of BRT under
this Note or any of the other Credit Facility Documents or for any claim based
thereon or otherwise in respect thereof, against any past, present or future
trustee, shareholder, officer or employee of BRT, 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 Payee and
each other party to this Note and the other Credit Facility Documents.

            CXL. Maker acknowledges and agrees that without limiting, modifying
or otherwise affecting in any respect the provisions of paragraph 25 of the
Credit Agreement, that (i) Payee shall have the sole obligation and
responsibility to fund its Credit Facility Percentage Interest (as set forth on
the Co-Lenders Certificate (the "Co-Lenders Certificate") being delivered to
Maker contemporaneously with the execution and delivery of this Note) in each
advance of the Credit Facility which is made, or required to be made, by
Co-Lenders in accordance with the provisions of the Credit Agreement and (ii)
Maker shall not have the right under any fact or circumstance to look to any
party other than Payee, including without limitation, Initial Co-Lenders or any
other Co-Lender, for the funding of the portion of the Credit Facility required
to be funded by Payee in accordance with the Credit Agreement and as set forth
in the Co-Lenders Certificate, if Payee shall default in doing so, all risk of
such loss being directly assumed in all respects by Maker.

            CXLI. This Note is being executed and delivered in connection with
an increase in the Credit Facility from up to $80,000,000 to up to $150,000,000
and this Note amends and restates in its entirety that certain Note dated as of
April 4, 1997 from Maker to Payee (the "Existing Note") but is not in payment,
satisfaction or cancellation of the outstanding indebtedness evidenced by the
Existing Note. Neither this Note nor any of the other Credit Facility Notes
dated the date hereof nor anything contained herein or therein shall be
construed as a substitution or novation of the indebtedness of Maker by the
Existing Note, which indebtedness (as so increased) shall remain in full force
and effect and is now evidenced by this Note and the other Credit Facility
Notes.
<PAGE>

            IN WITNESS WHEREOF, Maker has duly executed this Note the day and
year first above written.

                                    BRANDYWINE REALTY TRUST


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

                                    BRANDYWINE OPERATING PARTNERSHIP, L.P.

                                    By:   Brandywine Realty Trust, a Maryland 
                                          real estate investment trust, its 
                                          general partner


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

                                    LC/N HORSHAM LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    LC/N KEITH VALLEY LIMITED PARTNERSHIP I, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NICHOLS LANSDALE LIMITED PARTNERSHIP III, 
                                    a Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NEWTECH III LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    NEWTECH IV LIMITED PARTNERSHIP, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    C/N OAKLANDS LIMITED PARTNERSHIP I, a 
                                    Pennsylvania limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    FIFTEEN HORSHAM, L.P., a Pennsylvania 
                                    limited partnership

                                    By:   Witmer Operating Partnership I, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Holdings I, Inc., a
                                                Pennsylvania corporation, its
                                                general partner


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

                                    C/N LEEDOM LIMITED PARTNERSHIP II, a 
                                    Pennsylvania limited partnership
<PAGE>

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    C/N IRON RUN LIMITED PARTNERSHIP III, a 
                                    Pennsylvania limited partnership

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          its general partner

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    BRANDYWINE - MAIN STREET, LLC, a Delaware 
                                    limited liability company

                                    By:   Brandywine Operating Partnership, 
                                          L.P., a Delaware limited partnership, 
                                          a member

                                          By:   Brandywine Realty Trust, a 
                                                Maryland real estate investment 
                                                trust, its general partner


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

                                    By:   Brandywine Acquisitions, LLC, a 
                                          Delaware limited liability company, 
                                          a member
<PAGE>

                                          By:   Brandywine Operating 
                                                Partnership, L.P., a Delaware
                                                limited partnership, a member

                                                By:   Brandywine Realty Trust, 
                                                      a Maryland real estate 
                                                      investment trust, its 
                                                      general partner


                                                     By:  /s/ Gerard H. Sweeney
                                                        -----------------------
                                                        Name:  Gerard H. Sweeney
                                                        Title: President
<PAGE>

                                   Exhibit E-1

                                  AMENDMENT TO
                    OPEN-END MORTGAGE AND SECURITY AGREEMENT

       (This is an Amendment to a Mortgage which Secures Future Advances)

                  This Amendment entered into as of the 15th day of July, 1997,
      between ***[Brandywine Operating Partnership, L.P., a Delaware]*** limited
      partnership having an office c/o Brandywine Realty Trust, Newtown Square
      Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
      Pennsylvania (hereinafter referred to as "Mortgagor"); and NationsBank,
      N.A., a national banking association having an office at 8300 Greensboro
      Drive, McLean, Virginia, not individually, but acting in its capacity as
      administrative and documentation agent for the equal and ratable benefit
      of Co-Lenders, pursuant to and in accordance with the terms and provisions
      of the Credit Agreement (NationsBank, N.A., acting in such capacity as
      administrative and documentation agent being hereinafter referred to as
      "Mortgagee").

                              PRELIMINARY STATEMENT

            A. All capitalized terms as used in this Amendment shall, unless
otherwise defined in this Amendment, have the meanings given to such terms in
the Mortgage (as described on Exhibit A attached hereto).

            B. Mortgagor is the owner of a fee estate in the premises described
in Exhibit B attached hereto (hereinafter referred to as the "Premises").

            C. Co-Lenders have, pursuant to the terms of the Credit Agreement,
previously extended to Borrowers a revolving credit facility in the principal
sum of up to, but not in excess of, $80,000,000 (hereinafter referred to as the
"Existing Credit Facility").

            D. In connection with the Existing Credit Facility, and as partial
security therefor, Mortgagor has previously executed and delivered the Mortgage
to Mortgagee and Mortgagee is the owner and holder of the Mortgage covering the
fee estate of Mortgagor in the Premises.

            E. At the request of Borrowers, Co-Lenders and Mortgagee have agreed
to increase the Existing Credit Facility from up to $80,000,000 to up to
$150,000,000 (hereinafter referred to as the "Credit Facility Increase"; the
Existing Credit Facility, as so increased, is hereinafter referred to as the
"Credit Facility").

            F. The Co-Lenders and Mortgagee were willing to agree to the Credit
Facility Increase only if (i) Borrowers and certain other parties enter 
<PAGE>

into a certain First Amendment of Credit Agreement and Other Credit Facility
Documents dated the date hereof (the "First Amendment"), (ii) Mortgagor and the
other Borrowers execute and deliver the other amendments to the Credit Facility
Documents as contemplated by the First Amendment and (iii) Mortgagor executes
and delivers this Amendment.

            NOW, THEREFORE, in consideration of the premises and other good and
valuable consideration, the receipt of which is hereby acknowledged, and in
order to induce Co-Lenders and Mortgagee to agree to the Credit Facility
Increase, Mortgagor covenants and agrees with and represents and warrants to
Mortgagee as follows:

            CXLII. Amendments. From and after the date of this Amendment, the
Mortgage is hereby modified and amended in the following respects:

            a. The "NOW, THEREFORE" clause contained in Paragraph E of the
      Preliminary Statement of the Mortgage is deleted in its entirety and the
      following clause is substituted therefor:

                  "E. NOW, THEREFORE, to secure the payment of an indebtedness
            in the principal sum of up to, but not in excess of, One Hundred
            Fifty Million and 00/100 Dollars ($150,000,000.00), lawful money of
            the United States of America, or so much thereof as may be advanced
            and readvanced and be outstanding from time to time in accordance
            with the provisions of the Credit Agreement, to be paid with
            interest in accordance with the provisions of the Credit Facility
            Notes and the Credit Agreement (said indebtedness, interest and any
            and all sums which may or shall become due in accordance with the
            provisions of the Credit Facility Documents being hereinafter
            collectively referred to as the "Debt"), Mortgagor has mortgaged,
            created a security interest in, given, granted, bargained, sold,
            aliened, enfeoffed, conveyed, confirmed and assigned, and by these
            presents does mortgage, create a security interest in, give, grant,
            bargain, sell, alien, enfeoff, convey, confirm and assign unto
            Mortgagee forever all right, title and interest of Mortgagor now
            owned, or hereafter acquired, in and to the following property,
            rights and interests (such property, rights and interests being
            hereinafter collectively referred to as the "Mortgaged Property"):"

            b. The following definition is hereby inserted in Exhibit A of the
      Mortgage in its appropriate alphabetical order:
<PAGE>

            "BMS: The term "BMS" as used in this Mortgage shall mean
            Brandywine-Main Street, LLC, a Delaware limited liability company."

            c. The definition of "Borrowers" appearing in Exhibit A of the
      Mortgage is deleted in its entirety and the following definition is
      substituted therefor:

            "Borrowers: The term "Borrowers" as used in this Mortgage shall
            collectively mean BRT, BOP, BMS and the BRT/BOP Limited
            Partnerships."

            d. The definition of "Co-Lenders" appearing in Exhibit A of the
      Mortgage is deleted in its entirety and the following definition is
      substituted therefor:

            "Co-Lenders: The term "Co-Lenders" as used in this Mortgage shall
            mean, collectively, Smith Barney, NB, The First National Bank of
            Chicago, a national banking association, Mellon Bank, N.A., a
            national banking association, PNC Bank, National Association, a
            national banking association, Signet Bank, a state banking
            association organized under the laws of the Commonwealth of
            Virginia, Summit Bank, a state banking association organized under
            the laws of the State of New Jersey, and all other parties from time
            to time to whom direct interests in the Credit Facility are sold,
            transferred and assigned, and who are as a result thereof designated
            as Co-Lenders, under and pursuant to the provisions of the Credit
            Agreement and the Co-Lenders Agreement."

            CXLIII. Confirmation and Reaffirmation of Mortgagor. Mortgagor
confirms and reaffirms that the Mortgage, as modified and amended pursuant to
the provisions of this Amendment, and the lien thereof encumbers all of the
right, title and interest of Mortgagor, now owned, or hereafter acquired, in and
to the Mortgaged Property (as hereinafter defined). In furtherance of the
foregoing but without limitation of the terms of the granting clause of the
Mortgage, Mortgagor confirms and reaffirms that pursuant to the terms of the
Mortgage, as modified by this Amendment, Mortgagor does mortgage, create a
security interest in, give, grant, bargain, sell, alien, enfeoff, convey,
confirm and assign unto Mortgagee forever all right, title and interest of
Mortgagor now owned, or hereafter acquired, in and to the following property,
rights and interests (such property, rights and interests being hereinafter
collectively referred to as the "Mortgaged Property"):
<PAGE>

                  (a) the Premises;

                  (b) all buildings and improvements now or hereafter located on
            the Premises;

                  (c) all of the estate, right, title, claim or demand of any
            nature whatsoever of Mortgagor, either in law or in equity, in
            possession or expectancy, in and to the Mortgaged Property or any
            part thereof;

                  (d) all easements, rights-of-way, gores of land, streets,
            ways, alleys, passages, sewer rights, waters, water courses, water
            rights and powers, and all estates, rights, titles, interests,
            privileges, liberties, tenements, hereditaments, and appurtenances
            of any nature whatsoever, in any way belonging, relating or
            pertaining to the Mortgaged Property (including, without limitation,
            any and all development rights, air rights or similar or comparable
            rights of any nature whatsoever now or hereafter appurtenant to the
            Premises or now or hereafter transferred to the Premises) and all
            land lying in the bed of any street, road or avenue, opened or
            proposed, in front of or adjoining the Premises to the center line
            thereof;

                  (e) all FF&E and the right, title and interest of Mortgagor in
            and to any of the FF&E which may be subject to any security
            agreements (as defined in the Uniform Commercial Code) superior in
            lien to the lien of the Mortgage;

                  (f) all awards or payments, including interest thereon, if
            any, and the right to receive the same, which may be made with
            respect to the Mortgaged Property, whether from the exercise of the
            right of eminent domain (including any transfer made in lieu of the
            exercise of said right), or for any other injury to or decrease in
            the value of the Mortgaged Property;

                  (g) all leases, licenses and other agreements affecting or
            relating to the use or occupancy of the Mortgaged Property now or
            hereafter entered into and the right to receive and apply the rents,
            income, revenues, receipts, accounts, accounts receivable, issues
            and profits of or derived from or relating to the Mortgaged Property
            to the payment of the Debt;

                  (h) all proceeds of and any unearned premiums on any insurance
            policies covering the Mortgaged Property, including, without
            limitation, the right (subject to the provisions of the Credit
            Agreement) to receive and apply the proceeds of any insurance,
            judgments, or settlements made in lieu thereof, for damage to the
            Mortgaged Property; and

                  (i) the right to appear in and defend any action, case or
            proceeding brought with respect to the Mortgaged Property and to
<PAGE>

            commence any action, case or proceeding to protect the interest of
            Mortgagee in the Mortgaged Property.

            TO HAVE AND TO HOLD the above granted and described Mortgaged
Property unto and to the proper use and benefit of Mortgagee, and the successors
and assigns of Mortgagee, forever;

            PROVIDED, HOWEVER, that if Mortgagor shall pay, perform and
discharge the obligations secured by the Mortgage, as modified by this
Amendment, in full, then the Mortgage, as modified by this Amendment and the
estate thereby and hereby granted shall cease, terminate and become void.

            CXLIV. Amendment to Open-End Mortgage. This Amendment is an
amendment to an open-end mortgage securing future advances pursuant to 42 Pa.
C.S.A. ss.8143. Without limiting the foregoing or any other provision of the
Mortgage, as modified by this Amendment, the Mortgage (as modified by this
Amendment) secures, inter alia, present and future advances of the Credit
Facility made by Co-Lenders or Mortgagee pursuant to the Credit Agreement and/or
the other Credit Facility Documents; advances made by Mortgagee or Co-Lenders
with respect to the Mortgaged Property for the payment of taxes, assessments,
maintenance charges, insurance premiums or costs incurred for the protection of
the Mortgaged Property or the lien of this Amendment; and expenses incurred by
Mortgagee or Co-Lenders by reason of the occurrence of an Event of Default. The
priority of such future advances and expenses shall relate back to the date of
the Mortgage, or to such later date as required by applicable law, regardless of
the date upon which such advances are made or such expenses are incurred. If the
Credit Facility Documents provide that any advances of the Credit Facility shall
be made by Co-Lenders upon completion by Mortgagor of certain performance
obligations under the Credit Agreement and/or the other Credit Facility
Documents (including, without limitation, compliance with the terms of the
Credit Agreement and/or the other Credit Facility Documents such that no default
or Event of Default shall have occurred), such advances of the Credit Facility
shall be deemed "obligatory advances" solely for the purpose of the application
of the obligatory advance doctrine to confirm the lien priority of such advances
of the Credit Facility actually made by Co-Lenders, whether such advances of the
Credit Facility are initially either (1) advanced by Co-Lenders or Mortgagee
into an escrow subject to Mortgagee's or Co-Lenders' control or (2) retained by
Co-Lenders or Mortgagee.

            CXLV. Incorporation of First Amendment. All references in the
Mortgage to (i) the Credit Facility Notes shall be deemed to refer to the
Restated Credit Facility Notes and (ii) the Credit Agreement, the Credit
Facility Documents and the Credit Facility shall be deemed to refer to the
Credit Agreement and the Credit Facility Documents, as modified and amended by
the execution and delivery of the First Amendment, and to the Credit Facility,
as increased in the manner contemplated by the First Amendment.

            CXLVI. Prompt Recordation; Payment of Certain Fees and Expenses.
Mortgagor shall promptly cause this Amendment to be filed, registered or
recorded in such manner and in such places as may be required by any present or
future law in order to publish notice of and fully to protect the lien of the
Mortgage, as modified and amended pursuant to the provisions
<PAGE>

of this Amendment, upon, and the interest of Mortgagee, in the Mortgaged
Property. Mortgagor will pay all filing, registration and recording fees, and
all expenses incident to the preparation, execution, acknowledgment and
enforcement of this Amendment, and all Federal, state, county and municipal
taxes, documentary stamps, intangible taxes, duties, imposts, assessments and
charges arising out of or in connection with the filing, registration,
recording, execution and delivery of this Amendment, and Mortgagor shall hold
harmless and indemnify Mortgagee against any liability incurred by reason of the
imposition of any tax on the issuance making, filing, registration or recording
of this Amendment.

            CXLVII. Not a Novation. This Amendment constitutes a modification of
the Credit Facility Documents, and is not intended to and shall not terminate or
extinguish any of the indebtedness or obligations under the Credit Facility
Notes, the Mortgage and the other Credit Facility Documents and shall not
constitute a novation of the original indebtedness or obligations under the
Credit Facility Notes, the Mortgage and the other Credit Facility Documents nor
shall this Amendment affect or impair in any manner whatsoever the attachment,
perfection and/or priority of any liens created thereby, it being the intention
of the parties hereto to carry forward all liens and security interests securing
payment of the Credit Facility Notes, which liens and interest are acknowledged
by Mortgagor to be valid and subsisting against the Mortgaged Property.

            CXLVIII. Exculpation. No recourse shall be had for any obligation of
BRT under the Mortgage, as modified by this Amendment, or any of the other
Credit Facility Documents or for any claim based thereon or otherwise in respect
thereof, against any past, present or future trustee, shareholder, officer or
employee of BRT, 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 each other party to this Amendment and the
other Credit Facility Documents.

            CXLIX. No Offsets, etc. Mortgagor represents, warrants and covenants
that there are no offsets, counterclaims or defenses against the Debt, the
Credit Facility Notes, the Credit Agreement, the Mortgage or the Other Credit
Facility Documents.

            CL. Authorization. Mortgagor represents, warrants and covenants that
Mortgagor (and the undersigned representative of Mortgagor, if any) has full
power, authority and legal right to execute this Amendment and to keep and
observe all of the terms of this Amendment on Mortgagor's part to be observed
and performed.

            CLI. Counterparts. This Amendment may be executed in any number of
duplicate originals and each such duplicate original shall be deemed to
constitute but one and the same instrument.

            CLII. Savings Clause. If any term, covenant or condition of this
Amendment shall be held to be invalid, illegal or unenforceable in any respect,
this Amendment shall be construed without such provision.
<PAGE>

            CLIII. Full Force and Effect. All of the terms, covenants and
conditions of the Mortgage shall, except as expressly modified and amended
pursuant to the provisions of this Amendment, remain in full force and effect.

            CLIV. No Oral Modifications, etc. This Amendment may not be
modified, amended or terminated, except by an agreement in writing signed by the
parties hereto.

            CLV. Successors and Assigns. This Amendment shall be binding upon
and inure to the benefit of the parties hereto and their respective successors
and assigns.

            CLVI. Governing Law. This Amendment shall be governed by and
construed in accordance with the laws of the state in which the Premises are
located.
<PAGE>

            IN WITNESS WHEREOF, Mortgagor and Mortgagee have duly executed this
Amendment as of the day and year first above written.


                                       BRANDYWINE OPERATING PARTNERSHIP, L.P., a
                                       Delaware limited partnership

                                       By:   Brandywine Realty Trust, a Maryland
                                             real estate investment trust


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

                                       NATIONSBANK, N.A., not individually but 
                                       acting in its capacity as administrative 
                                       and documentation agent for the equal and
                                       ratable benefit of Co-Lenders


                                       By:   /s/ Cheryl D. Fitzgerald
                                             --------------------------------
                                             Name:   Cheryl D. Fitzgerald
                                             Title:  Vice President

                    Certificate of Residence of the Mortgagee

            The business address of the Mortgagee herein is 8300 Greensboro
Drive, McLean, Virginia 22102-3604.


                                        ----------------------------
                                        Agent/Attorney for Mortgagee
<PAGE>

STATE OF          )
                  ) ss.:
COUNTY OF         )

            On this, the ____ day of July, 1997, before me, a Notary Public, the
undersigned officer, personally appeared Cheryl D. Fitzgerald, a Vice President
of NationsBank, N.A., a national banking association, known to me (or
satisfactorily proven) to be the person whose name is subscribed to the within
instrument, and acknowledged that he/she executed the same on behalf of the
association in the capacity therein stated and for the purposes therein
contained.


                                        -------------------------------
                                        Notary Public

[SEAL]

My Commission Expires:
<PAGE>

                                ACKNOWLEDGEMENTS

                                (To be attached)
<PAGE>

                                    EXHIBIT A

                          (Description of the Mortgage)

Mortgage: Open-End Mortgage and Security Agreement dated as of ***[November 25,
1996 OR May 21, 1997]*** given by Mortgagor to Mortgagee and recorded on
_______, 1997 in _______, page _______ in the office of the __________ of
__________ County, Pennsylvania.
<PAGE>

                                   *EXHIBIT B

                            (Description of Premises)

- ----------
* Legal description of premises should include insurable description of any
easements which are appurtenant to the Premises.
<PAGE>

================================================================================

                   ***[Brandywine Operating Partnership, L.P.,
                a Delaware]*** limited partnership, as Mortgagor

                                       and

                       NationsBank, N.A., not individually
                  but acting in its capacity as administrative
                    and documentation agent for the equal and
                        ratable benefit of the co-lenders
                         described herein, as Mortgagee

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

                                  AMENDMENT TO
                    OPEN-END MORTGAGE AND SECURITY AGREEMENT
       (This is an Amendment to a Mortgage which Secures Future Advances)

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

                           Dated: As of July 15, 1997

                           Location: ___________________
                                     ________ County, Pennsylvania

                           RECORD AND RETURN TO:

                           Battle Fowler LLP
                           Park Avenue Tower
                           75 East 55th Street
                           New York, New York 10022

                           Attention: Dean A. Stiffle, Esq.
<PAGE>

                       Uniform Parcel Identifier: _______

================================================================================
<PAGE>

                                   Exhibit E-2

                                                                      New Jersey

                                  AMENDMENT TO
                                    MORTGAGE

                  This Amendment entered into as of the 15th day of July, 1997,
      between ***[Brandywine Operating Partnership, L.P., a Delaware limited
      partnership]*** having an office c/o Brandywine Realty Trust, Newtown
      Square Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
      Pennsylvania (hereinafter referred to as "Mortgagor"); and NationsBank,
      N.A., a national banking association having an office at 8300 Greensboro
      Drive, McLean, Virginia, not individually, but acting in its capacity as
      administrative and documentation agent for the equal and ratable benefit
      of Co-Lenders, pursuant to and in accordance with the terms and provisions
      of the Credit Agreement (NationsBank, N.A., acting in such capacity as
      administrative and documentation agent being hereinafter referred to as
      "Mortgagee").

                              PRELIMINARY STATEMENT

            A. All capitalized terms as used in this Amendment shall, unless
otherwise defined in this Amendment, have the meanings given to such terms in
the Mortgage (as described on Exhibit A attached hereto).

            B. Mortgagor is the owner of a fee estate in the premises described
in Exhibit B attached hereto (hereinafter referred to as the "Premises").

            C. Co-Lenders have, pursuant to the terms of the Credit Agreement,
previously extended to Borrowers a revolving credit facility in the principal
sum of up to, but not in excess of, $80,000,000 (hereinafter referred to as the
"Existing Credit Facility").

            D. In connection with the Existing Credit Facility, and as partial
security therefor, Mortgagor has previously executed and delivered the Mortgage
to Mortgagee and Mortgagee is the owner and holder of the Mortgage covering the
fee estate of Mortgagor in the Premises.

            E. At the request of Borrowers, Co-Lenders and Mortgagee have agreed
to increase the Existing Credit Facility from up to $80,000,000 to up to
$150,000,000 (hereinafter referred to as the "Credit Facility Increase"; the
Existing Credit Facility, as so increased, is hereinafter referred to as the
"Credit Facility").
<PAGE>

            F. The Co-Lenders and Mortgagee were willing to agree to the Credit
Facility Increase only if (i) Borrowers and certain other parties enter into a
certain First Amendment of Credit Agreement and Other Credit Facility Documents
dated the date hereof (the "First Amendment"), (ii) Mortgagor and the other
Borrowers execute and deliver the other amendments to the Credit Facility
Documents as contemplated by the First Amendment and (iii) Mortgagor executes
and delivers this Amendment.

            NOW, THEREFORE, in consideration of the premises and other good and
valuable consideration, the receipt of which is hereby acknowledged, and in
order to induce Co-Lenders and Mortgagee to agree to the Credit Facility
Increase, Mortgagor covenants and agrees with and represents and warrants to
Mortgagee as follows:

            CLVII. Amendments. From and after the date of this Amendment, the
Mortgage is hereby modified and amended in the following respects:

            a. The "NOW, THEREFORE" clause contained in Paragraph E of the
      Preliminary Statement of the Mortgage is deleted in its entirety and the
      following clause is substituted therefor:

                  "E. NOW, THEREFORE, to secure the payment of an indebtedness
            in the principal sum of up to, but not in excess of, One Hundred
            Fifty Million and 00/100 Dollars ($150,000,000.00), lawful money of
            the United States of America, or so much thereof as may be advanced
            and readvanced and be outstanding from time to time in accordance
            with the provisions of the Credit Agreement, to be paid with
            interest in accordance with the provisions of the Credit Facility
            Notes and the Credit Agreement (said indebtedness, interest and any
            and all sums which may or shall become due in accordance with the
            provisions of the Credit Facility Documents being hereinafter
            collectively referred to as the "Debt"), Mortgagor has mortgaged,
            created a security interest in, given, granted, bargained, sold,
            aliened, enfeoffed, conveyed, confirmed and assigned, and by these
            presents does mortgage, create a security interest in, give, grant,
            bargain, sell, alien, enfeoff, convey, confirm and assign unto
            Mortgagee forever all right, title and interest of Mortgagor now
            owned, or hereafter acquired, in and to the following property,
            rights and interests (such property, rights and interests being
            hereinafter collectively referred to as the "Mortgaged Property"):"

            b. The following definition is hereby inserted in Exhibit A of the
      Mortgage in its appropriate alphabetical order:
<PAGE>

            "BMS: The term "BMS" as used in this Mortgage shall mean
            Brandywine-Main Street, LLC, a Delaware limited liability company."

            c. The definition of "Borrowers" appearing in Exhibit A of the
      Mortgage is deleted in its entirety and the following definition is
      substituted therefor: 

            "Borrowers: The term "Borrowers" as used in this Mortgage shall
            collectively mean BRT, BOP, BMS and the BRT/BOP Limited
            Partnerships."

            d. The definition of "Co-Lenders" appearing in Exhibit A of the
      Mortgage is deleted in its entirety and the following definition is
      substituted therefor:

            "Co-Lenders: The term "Co-Lenders" as used in this Mortgage shall
            mean, collectively, Smith Barney, NB, The First National Bank of
            Chicago, a national banking association, Mellon Bank, N.A., a
            national banking association, PNC Bank, National Association, a
            national banking association, Signet Bank, a state banking
            association organized under the laws of the Commonwealth of
            Virginia, Summit Bank, a state banking association organized under
            the laws of the State of New Jersey, and all other parties from time
            to time to whom direct interests in the Credit Facility are sold,
            transferred and assigned, and who are as a result thereof designated
            as Co-Lenders, under and pursuant to the provisions of the Credit
            Agreement and the Co-Lenders Agreement."

            CLVIII. Confirmation and Reaffirmation of Mortgagor. Mortgagor
confirms and reaffirms that the Mortgage, as modified and amended pursuant to
the provisions of this Amendment, and the lien thereof encumbers all of the
right, title and interest of Mortgagor, now owned, or hereafter acquired, in and
to the Mortgaged Property (as hereinafter defined). In furtherance of the
foregoing but without limitation of the terms of the granting clause of the
Mortgage, Mortgagor confirms and reaffirms that pursuant to the terms of the
Mortgage, as modified by this Amendment, Mortgagor does mortgage, create a
security interest in, give, grant, bargain, sell, alien, enfeoff, convey,
confirm and assign unto Mortgagee forever all right, title and interest of
Mortgagor now owned, or hereafter acquired, in and to the following property,
rights and 
<PAGE>

interests (such property, rights and interests being hereinafter collectively
referred to as the "Mortgaged Property"):

                  (a) the Premises;

                  (b) all buildings and improvements now or hereafter located on
            the Premises;

                  (c) all of the estate, right, title, claim or demand of any
            nature whatsoever of Mortgagor, either in law or in equity, in
            possession or expectancy, in and to the Mortgaged Property or any
            part thereof;

                  (d) all easements, rights-of-way, gores of land, streets,
            ways, alleys, passages, sewer rights, waters, water courses, water
            rights and powers, and all estates, rights, titles, interests,
            privileges, liberties, tenements, hereditaments, and appurtenances
            of any nature whatsoever, in any way belonging, relating or
            pertaining to the Mortgaged Property (including, without limitation,
            any and all development rights, air rights or similar or comparable
            rights of any nature whatsoever now or hereafter appurtenant to the
            Premises or now or hereafter transferred to the Premises) and all
            land lying in the bed of any street, road or avenue, opened or
            proposed, in front of or adjoining the Premises to the center line
            thereof;

                  (e) all FF&E and the right, title and interest of Mortgagor in
            and to any of the FF&E which may be subject to any security
            agreements (as defined in the Uniform Commercial Code) superior in
            lien to the lien of the Mortgage;

                  (f) all awards or payments, including interest thereon, if
            any, and the right to receive the same, which may be made with
            respect to the Mortgaged Property, whether from the exercise of the
            right of eminent domain (including any transfer made in lieu of the
            exercise of said right), or for any other injury to or decrease in
            the value of the Mortgaged Property;

                  (g) all leases, licenses and other agreements affecting or
            relating to the use or occupancy of the Mortgaged Property now or
            hereafter entered into and the right to receive and apply the rents,
            income, revenues, receipts, accounts, accounts receivable, issues
            and profits of or derived from or relating to the Mortgaged Property
            to the payment of the Debt;

                  (h) all proceeds of and any unearned premiums on any insurance
            policies covering the Mortgaged Property, including, without
            limitation, the right (subject to the provisions of the Credit
            Agreement) to receive and apply the proceeds of any insurance,
            judgments, or settlements made in lieu thereof, for damage to the
            Mortgaged Property; and
<PAGE>

                  (i) the right to appear in and defend any action, case or
            proceeding brought with respect to the Mortgaged Property and to
            commence any action, case or proceeding to protect the interest of
            Mortgagee in the Mortgaged Property.

            TO HAVE AND TO HOLD the above granted and described Mortgaged
Property unto and to the proper use and benefit of Mortgagee, and the successors
and assigns of Mortgagee, forever;

            PROVIDED, HOWEVER, that if Mortgagor shall pay, perform and
discharge the obligations secured by the Mortgage, as modified by this
Amendment, in full, then the Mortgage, as modified by this Amendment and the
estate thereby and hereby granted shall cease, terminate and become void.

            CLIX. Incorporation of First Amendment. All references in the
Mortgage to (i) the Credit Facility Notes shall be deemed to refer to the
Restated Credit Facility Notes and (ii) the Credit Agreement, the Credit
Facility Documents and the Credit Facility shall be deemed to refer to the
Credit Agreement and the Credit Facility Documents, as modified and amended by
the execution and delivery of the First Amendment, and to the Credit Facility,
as increased in the manner contemplated by the First Amendment.

            CLX. Prompt Recordation; Payment of Certain Fees and Expenses.
Mortgagor shall promptly cause this Amendment to be filed, registered or
recorded in such manner and in such places as may be required by any present or
future law in order to publish notice of and fully to protect the lien of the
Mortgage, as modified and amended pursuant to the provisions of this Amendment,
upon, and the interest of Mortgagee, in the Mortgaged Property. Mortgagor will
pay all filing, registration and recording fees, and all expenses incident to
the preparation, execution, acknowledgment and enforcement of this Amendment,
and all Federal, state, county and municipal taxes, documentary stamps,
intangible taxes, duties, imposts, assessments and charges arising out of or in
connection with the filing, registration, recording, execution and delivery of
this Amendment, and Mortgagor shall hold harmless and indemnify Mortgagee
against any liability incurred by reason of the imposition of any tax on the
issuance making, filing, registration or recording of this Amendment.
<PAGE>

            CLXI. Not a Novation. This Amendment constitutes a modification of
the Credit Facility Documents, and is not intended to and shall not terminate or
extinguish any of the indebtedness or obligations under the Credit Facility
Notes, the Mortgage and the other Credit Facility Documents and shall not
constitute a novation of the original indebtedness or obligations under the
Credit Facility Notes, the Mortgage and the other Credit Facility Documents nor
shall this Amendment affect or impair in any manner whatsoever the attachment,
perfection and/or priority of any liens created thereby, it being the intention
of the parties hereto to carry forward all liens and security interests securing
payment of the Credit Facility Notes, which liens and interest are acknowledged
by Mortgagor to be valid and subsisting against the Mortgaged Property.

            CLXII. Exculpation. No recourse shall be had for any obligation of
BRT under the Mortgage, as modified by this Amendment, or any of the other
Credit Facility Documents or for any claim based thereon or otherwise in respect
thereof, against any past, present or future trustee, shareholder, officer or
employee of BRT, 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 each other party to this Amendment and the
other Credit Facility Documents.

            CLXIII. No Offsets, etc. Mortgagor represents, warrants and
covenants that there are no offsets, counterclaims or defenses against the Debt,
the Credit Facility Notes, the Credit Agreement, the Mortgage or the Other
Credit Facility Documents.

            CLXIV. Authorization. Mortgagor represents, warrants and covenants
that Mortgagor (and the undersigned representative of Mortgagor, if any) has
full power, authority and legal right to execute this Amendment and to keep and
observe all of the terms of this Amendment on Mortgagor's part to be observed
and performed.

            CLXV. Counterparts. This Amendment may be executed in any number of
duplicate originals and each such duplicate original shall be deemed to
constitute but one and the same instrument.

            CLXVI. Savings Clause. If any term, covenant or condition of this
Amendment shall be held to be invalid, illegal or unenforceable in any respect,
this Amendment shall be construed without such provision.

            CLXVII. Full Force and Effect. All of the terms, covenants and
conditions of the Mortgage shall, except as expressly modified and amended
pursuant to the provisions of this Amendment, remain in full force and effect.

            CLXVIII. No Oral Modifications, etc. This Amendment may not be
modified, amended or terminated, except by an agreement in writing signed by the
parties hereto.
<PAGE>

            CLXIX. Successors and Assigns. This Amendment shall be binding upon
and inure to the benefit of the parties hereto and their respective successors
and assigns.

            CLXX. Governing Law. This Amendment shall be governed by and
construed in accordance with the laws of the state in which the Premises are
located.
<PAGE>

            IN WITNESS WHEREOF, Mortgagor and Mortgagee have duly executed this
Amendment as of the day and year first above written.


                                       ***[BRANDYWINE OPERATING PARTNERSHIP, 
                                       L.P., a Delaware limited partnership]***

                                       By:   Brandywine Realty Trust, a Maryland
                                             real estate investment trust


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

                                       NATIONSBANK, N.A., not individually but 
                                       acting in its capacity as administrative
                                       and documentation agent for the equal and
                                       ratable benefit of Co-Lenders


                                       By:   /s/ Cheryl D. Fitzgerald
                                             -------------------------------
                                             Name:   Cheryl D. Fitzgerald
                                             Title:  Vice President
<PAGE>

STATE OF         )
                 ) ss.:
COUNTY OF        )

            I certify, that on July ____, 1997, Cheryl D. Fitzgerald personally
came before me and this person acknowledged under oath, to my satisfaction,
that:

            (a) this person signed, sealed and delivered the attached document
            as Vice President of NationsBank, N.A., a national banking
            association, the banking association named in this document; and

            (b) this document was signed and made by the banking association as
            its voluntary act and deed by virtue of authority from its board of
            directors.


                                        -------------------------------
                                        Notary Public

My Commission Expires:
<PAGE>

                                ACKNOWLEDGEMENTS

                                (To be attached)
<PAGE>

                                    EXHIBIT A

                          (Description of the Mortgage)

Mortgage: Mortgage dated as of ***[November 25, 1996 OR May 21, 1997]*** given
by Mortgagor to Mortgagee and recorded on _______, 1997 in _______, page _______
in the office of the __________ of __________ County, New Jersey.
<PAGE>

                                   *EXHIBIT B

                            (Description of Premises)

- ----------
* Legal description of premises should include insurable description of any
easements which are appurtenant to the Premises.
<PAGE>

================================================================================

                   ***[Brandywine Operating Partnership, L.P.,
                a Delaware]*** limited partnership, as Mortgagor

                                       and

                       NationsBank, N.A., not individually
                  but acting in its capacity as administrative
                    and documentation agent for the equal and
                        ratable benefit of the co-lenders
                         described herein, as Mortgagee

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

                                  AMENDMENT TO
                                    MORTGAGE

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

                           Dated: As of July __, 1997

                           Location:  ___________________
                                      ________  County, New Jersey

                           RECORD AND RETURN TO:

                           Battle Fowler LLP
                           Park Avenue Tower
                           75 East 55th Street
                           New York, New York 10022

                           Attention: Dean A. Stiffle, Esq.

================================================================================
<PAGE>

                                         Master New Jersey Amendment to Mortgage

THIS AMENDMENT TO MORTGAGE
WAS PREPARED BY:


- ---------------------------
Attorney at Law
<PAGE>

                                   Exhibit E-3

                                  AMENDMENT TO
                                    MORTGAGE

                  This Amendment entered into as of the 15th day of July, 1997,
      between Brandywine Operating Partnership, L.P., a Delaware limited
      partnership having an office c/o Brandywine Realty Trust, Newtown Square
      Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
      Pennsylvania (hereinafter referred to as "Mortgagor"); and NationsBank,
      N.A., a national banking association having an office at 8300 Greensboro
      Drive, McLean, Virginia, not individually, but acting in its capacity as
      administrative and documentation agent for the equal and ratable benefit
      of Co-Lenders, pursuant to and in accordance with the terms and provisions
      of the Credit Agreement (NationsBank, N.A., acting in such capacity as
      administrative and documentation agent being hereinafter referred to as
      "Mortgagee").

                              PRELIMINARY STATEMENT

            A. All capitalized terms as used in this Amendment shall, unless
otherwise defined in this Amendment, have the meanings given to such terms in
the Mortgage (as described on Exhibit A attached hereto).

            B. Mortgagor is the owner of a leasehold estate in the premises
described in Exhibit B attached hereto (hereinafter referred to as the
"Premises") under and pursuant to the provisions of the lease described in
Exhibit B-1 attached hereto (hereinafter referred to as the "Ground Lease").

            C. Co-Lenders have, pursuant to the terms of the Credit Agreement,
previously extended to Borrowers a revolving credit facility in the principal
sum of up to, but not in excess of, $80,000,000 (hereinafter referred to as the
"Existing Credit Facility").

            D. In connection with the Existing Credit Facility, and as partial
security therefor, Mortgagor has previously executed and delivered the Mortgage
to Mortgagee and Mortgagee is the owner and holder of the Mortgage covering the
fee estate of Mortgagor in the Premises.

            E. At the request of Borrowers, Co-Lenders and Mortgagee have agreed
to increase the Existing Credit Facility from up to $80,000,000 to up to
$150,000,000 (hereinafter referred to as the "Credit Facility Increase"; the
Existing Credit Facility, as so increased, is hereinafter referred to as the
"Credit Facility").

            F. The Co-Lenders and Mortgagee were willing to agree to the Credit
Facility Increase only if (i) Borrowers and certain other parties enter into a
certain First Amendment of Credit Agreement and Other Credit Facility Documents
dated the date hereof (the "First Amendment"), (ii) Mortgagor and 
<PAGE>

the other Borrowers execute and deliver the other amendments to the Credit
Facility Documents as contemplated by the First Amendment and (iii) Mortgagor
executes and delivers this Amendment.

            NOW, THEREFORE, in consideration of the premises and other good and
valuable consideration, the receipt of which is hereby acknowledged, and in
order to induce Co-Lenders and Mortgagee to agree to the Credit Facility
Increase, Mortgagor covenants and agrees with and represents and warrants to
Mortgagee as follows:

            CLXXI. Amendments. From and after the date of this Amendment, the
Mortgage is hereby modified and amended in the following respects:

            a. The "NOW, THEREFORE" clause contained in Paragraph E of the
      Preliminary Statement of the Mortgage is deleted in its entirety and the
      following clause is substituted therefor:

                  "E. NOW, THEREFORE, to secure the payment of an indebtedness
            in the principal sum of up to, but not in excess of, One Hundred
            Fifty Million and 00/100 Dollars ($150,000,000.00), lawful money of
            the United States of America, or so much thereof as may be advanced
            and readvanced and be outstanding from time to time in accordance
            with the provisions of the Credit Agreement, to be paid with
            interest in accordance with the provisions of the Credit Facility
            Notes and the Credit Agreement (said indebtedness, interest and any
            and all sums which may or shall become due in accordance with the
            provisions of the Credit Facility Documents being hereinafter
            collectively referred to as the "Debt"), Mortgagor has mortgaged,
            created a security interest in, given, granted, bargained, sold,
            aliened, enfeoffed, conveyed, confirmed and assigned, and by these
            presents does mortgage, create a security interest in, give, grant,
            bargain, sell, alien, enfeoff, convey, confirm and assign unto
            Mortgagee forever all right, title and interest of Mortgagor now
            owned, or hereafter acquired, in and to the following property,
            rights and interests (such property, rights and interests being
            hereinafter collectively referred to as the "Mortgaged Property"):"

            b. The following definition is hereby inserted in Exhibit A of the
      Mortgage in its appropriate alphabetical order:

            "BMS: The term "BMS" as used in this Mortgage shall mean
            Brandywine-Main Street, LLC, a Delaware limited liability company."
<PAGE>

            c. The definition of "Borrowers" appearing in Exhibit A of the
      Mortgage is deleted in its entirety and the following definition is
      substituted therefor: 

            "Borrowers: The term "Borrowers" as used in this Mortgage shall
            collectively mean BRT, BOP, BMS and the BRT/BOP Limited
            Partnerships."

            d. The definition of "Co-Lenders" appearing in Exhibit A of the
      Mortgage is deleted in its entirety and the following definition is
      substituted therefor:

            "Co-Lenders: The term "Co-Lenders" as used in this Mortgage shall
            mean, collectively, Smith Barney, NB, The First National Bank of
            Chicago, a national banking association, Mellon Bank, N.A., a
            national banking association, PNC Bank, National Association, a
            national banking association, Signet Bank, a state banking
            association organized under the laws of the Commonwealth of
            Virginia, Summit Bank, a state banking association organized under
            the laws of the State of New Jersey, and all other parties from time
            to time to whom direct interests in the Credit Facility are sold,
            transferred and assigned, and who are as a result thereof designated
            as Co-Lenders, under and pursuant to the provisions of the Credit
            Agreement and the Co-Lenders Agreement."

            CLXXII. Confirmation and Reaffirmation of Mortgagor. Mortgagor
confirms and reaffirms that the Mortgage, as modified and amended pursuant to
the provisions of this Amendment, and the lien thereof encumbers all of the
right, title and interest of Mortgagor, now owned, or hereafter acquired, in and
to the Mortgaged Property (as hereinafter defined). In furtherance of the
foregoing but without limitation of the terms of the granting clause of the
Mortgage, Mortgagor confirms and reaffirms that pursuant to the terms of the
Mortgage, as modified by this Amendment, Mortgagor does mortgage, create a
security interest in, give, grant, bargain, sell, alien, enfeoff, convey,
confirm and assign unto Mortgagee forever all right, title and interest of
Mortgagor now owned, or hereafter acquired, in and to the following property,
rights and interests (such property, rights and interests being hereinafter
collectively referred to as the "Mortgaged Property"):

                  (a) the Premises;
<PAGE>

                  (b) all buildings and improvements now or hereafter located on
            the Premises;

                  (b)(1) the Ground Lease and the leasehold estate created
            thereunder;

                  (b)(2) all modifications, extensions and renewals of the
            Ground Lease and all credits, deposits, options, purchase options,
            privileges and rights of Mortgagor under and in accordance with the
            provisions of the Ground Lease, including, but not limited to, the
            right, if any, to renew or extend the Ground Lease for a succeeding
            term or terms or to acquire fee title to or other interest in all or
            any portion of the Premises or the Improvements;

                  (c) all of the estate, right, title, claim or demand of any
            nature whatsoever of Mortgagor, either in law or in equity, in
            possession or expectancy, in and to the Mortgaged Property or any
            part thereof;

                  (d) all easements, rights-of-way, gores of land, streets,
            ways, alleys, passages, sewer rights, waters, water courses, water
            rights and powers, and all estates, rights, titles, interests,
            privileges, liberties, tenements, hereditaments, and appurtenances
            of any nature whatsoever, in any way belonging, relating or
            pertaining to the Mortgaged Property (including, without limitation,
            any and all development rights, air rights or similar or comparable
            rights of any nature whatsoever now or hereafter appurtenant to the
            Premises or now or hereafter transferred to the Premises) and all
            land lying in the bed of any street, road or avenue, opened or
            proposed, in front of or adjoining the Premises to the center line
            thereof;

                  (e) all FF&E and the right, title and interest of Mortgagor in
            and to any of the FF&E which may be subject to any security
            agreements (as defined in the Uniform Commercial Code) superior in
            lien to the lien of the Mortgage;

                  (f) all awards or payments, including interest thereon, if
            any, and the right to receive the same, which may be made with
            respect to the Mortgaged Property, whether from the exercise of the
            right of eminent domain (including any transfer made in lieu of the
            exercise of said right), or for any other injury to or decrease in
            the value of the Mortgaged Property;

                  (g) all leases, licenses and other agreements (other than the
            Ground Lease) affecting or relating to the use or occupancy of the
            Mortgaged Property now or hereafter entered into and the right to
            receive and apply the rents, income, revenues, receipts, accounts,
            accounts receivable, issues and profits of or derived from or
            relating to the Mortgaged Property to the payment of the Debt;
<PAGE>

                  (h) all proceeds of and any unearned premiums on any insurance
            policies covering the Mortgaged Property, including, without
            limitation, the right (subject to the provisions of the Credit
            Agreement) to receive and apply the proceeds of any insurance,
            judgments, or settlements made in lieu thereof, for damage to the
            Mortgaged Property; and

                  (i) the right to appear in and defend any action, case or
            proceeding brought with respect to the Mortgaged Property and to
            commence any action, case or proceeding to protect the interest of
            Mortgagee in the Mortgaged Property.

            TO HAVE AND TO HOLD the above granted and described Mortgaged
Property unto and to the proper use and benefit of Mortgagee, and the successors
and assigns of Mortgagee, forever;

            PROVIDED, HOWEVER, that if Mortgagor shall pay, perform and
discharge the obligations secured by the Mortgage, as modified by this
Amendment, in full, then the Mortgage, as modified by this Amendment and the
estate thereby and hereby granted shall cease, terminate and become void.

            CLXXIII. Incorporation of First Amendment. All references in the
Mortgage to (i) the Credit Facility Notes shall be deemed to refer to the
Restated Credit Facility Notes and (ii) the Credit Agreement, the Credit
Facility Documents and the Credit Facility shall be deemed to refer to the
Credit Agreement and the Credit Facility Documents, as modified and amended by
the execution and delivery of the First Amendment, and to the Credit Facility,
as increased in the manner contemplated by the First Amendment.

            CLXXIV. Prompt Recordation; Payment of Certain Fees and Expenses.
Mortgagor shall promptly cause this Amendment to be filed, registered or
recorded in such manner and in such places as may be required by any present or
future law in order to publish notice of and fully to protect the lien of the
Mortgage, as modified and amended pursuant to the provisions of this Amendment,
upon, and the interest of Mortgagee, in the Mortgaged Property. Mortgagor will
pay all filing, registration and recording fees, and all expenses incident to
the preparation, execution, acknowledgment and enforcement of this Amendment,
and all Federal, state, county and municipal taxes, documentary stamps,
intangible taxes, duties, imposts, assessments and charges arising out of or in
connection with the filing, registration, recording, execution and delivery of
this Amendment, and Mortgagor shall hold harmless and indemnify Mortgagee
against any liability incurred by reason of the imposition of any tax on the
issuance making, filing, registration or recording of this Amendment.
<PAGE>

            CLXXV. Not a Novation. This Amendment constitutes a modification of
the Credit Facility Documents, and is not intended to and shall not terminate or
extinguish any of the indebtedness or obligations under the Credit Facility
Notes, the Mortgage and the other Credit Facility Documents and shall not
constitute a novation of the original indebtedness or obligations under the
Credit Facility Notes, the Mortgage and the other Credit Facility Documents nor
shall this Amendment affect or impair in any manner whatsoever the attachment,
perfection and/or priority of any liens created thereby, it being the intention
of the parties hereto to carry forward all liens and security interests securing
payment of the Credit Facility Notes, which liens and interest are acknowledged
by Mortgagor to be valid and subsisting against the Mortgaged Property.

            CLXXVI. Exculpation. No recourse shall be had for any obligation of
BRT under the Mortgage, as modified by this Amendment, or any of the other
Credit Facility Documents or for any claim based thereon or otherwise in respect
thereof, against any past, present or future trustee, shareholder, officer or
employee of BRT, 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 each other party to this Amendment and the
other Credit Facility Documents.

            CLXXVII. No Offsets, etc. Mortgagor represents, warrants and
covenants that there are no offsets, counterclaims or defenses against the Debt,
the Credit Facility Notes, the Credit Agreement, the Mortgage or the Other
Credit Facility Documents.

            CLXXVIII. Authorization. Mortgagor represents, warrants and
covenants that Mortgagor (and the undersigned representative of Mortgagor, if
any) has full power, authority and legal right to execute this Amendment and to
keep and observe all of the terms of this Amendment on Mortgagor's part to be
observed and performed.

            CLXXIX. Counterparts. This Amendment may be executed in any number
of duplicate originals and each such duplicate original shall be deemed to
constitute but one and the same instrument.

            CLXXX. Savings Clause. If any term, covenant or condition of this
Amendment shall be held to be invalid, illegal or unenforceable in any respect,
this Amendment shall be construed without such provision.

            CLXXXI. Full Force and Effect. All of the terms, covenants and
conditions of the Mortgage shall, except as expressly modified and amended
pursuant to the provisions of this Amendment, remain in full force and effect.

            CLXXXII. No Oral Modifications, etc. This Amendment may not be
modified, amended or terminated, except by an agreement in writing signed by the
parties hereto.
<PAGE>

            CLXXXIII. Successors and Assigns. This Amendment shall be binding
upon and inure to the benefit of the parties hereto and their respective
successors and assigns.

            CLXXXIV. Governing Law. This Amendment shall be governed by and
construed in accordance with the laws of the state in which the Premises are
located.
<PAGE>

            IN WITNESS WHEREOF, Mortgagor and Mortgagee have duly executed this
Amendment as of the day and year first above written.


                                       BRANDYWINE OPERATING PARTNERSHIP, L.P., a
                                       Delaware limited partnership

                                       By:   Brandywine Realty Trust, a Maryland
                                             real estate investment trust


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

                                       NATIONSBANK, N.A., not individually but 
                                       acting in its capacity as administrative 
                                       and documentation agent for the equal and
                                       ratable benefit of Co-Lenders


                                       By:   /s/ Cheryl D. Fitzgerald
                                             ---------------------------------
                                             Name:   Cheryl D. Fitzgerald
                                             Title:  Vice President
<PAGE>

STATE OF _________)
                  ) ss.:
COUNTY OF ________)

            This instrument was acknowledged before me on July __, 1997, by
Gerard H. Sweeney, as the President and Chief Executive Officer of Brandywine
Realty Trust, a Maryland real estate investment trust, as the general partner of
Brandywine Operating Partnership, L.P., a Delaware limited partnership.


                                        -----------------------------------
                                        Notary Public

My Commission Expires:
<PAGE>

STATE OF _________)
                  ) ss.:
COUNTY OF ________)

            This instrument was acknowledged before me on July __, 1997, by
Cheryl D. Fitzgerald, as a Vice President of NationsBank, N.A., a national
banking association.


                                        ---------------------------------
                                        Notary Public

My Commission Expires:
<PAGE>

                                    EXHIBIT A

                          (Description of the Mortgage)

Mortgage: Mortgage dated as of November 25, 1996 given by Mortgagor to Mortgagee
and recorded on January 6, 1997 in Book 4452, page 0093 in the office of the
Recorder of Deeds of New Castle County, Delaware.
<PAGE>

                                   *EXHIBIT B

                            (Description of Premises)

- ----------
* Legal description of premises should include insurable description of any
easements which are appurtenant to the Premises.
<PAGE>

                                   EXHIBIT B-1

                          (Description of Ground Lease)

Ground Lease: The term "Ground Lease" as used in this Amendment shall mean,
collectively, the following:

            That certain Ground Lease dated as of May 31, 1988 by and between
Woodlawn Trustees, Incorporated, a Delaware corporation, as ground lessor, and
Donahoe Wilmington Associates One Limited Partnership, a Delaware limited
partnership, as ground lessee, and recorded on June 3, 1988 in the Office of the
Recorder of Deeds for New Castle County, Delaware in Deed Book 711, Page 34.

            The ground lessee's interest in the foregoing was assigned by that
certain Deed of Michael P. Walsh, Sheriff of New Castle County, Delaware, as
assignor, dated March 15, 1995 and given to New York Life Insurance and Annuity
Corporation, a Delaware corporation, as assignee, and recorded in the Office of
the Recorder of Deeds for New Castle County, Delaware in Deed Book 1895, Page
253.

            The ground lessee's interest in the foregoing was further assigned
by that certain Assignment and Assumption Agreement dated as of June 29, 1995 by
and between New York Life Insurance and Annuity Corporation, a Delaware
corporation, as assignor, and KB Fund II, a Delaware general partnership, as
assignee, and recorded on July 14, 1995 in the Office of the Recorder of Deeds
for New Castle County, Delaware in Deed Book 1949, Page 301.

            The ground lessee's interest in the foregoing was further assigned
by that certain Assignment and Assumption of Ground Lease dated December 2, 1996
by and between KB Fund II, a Delaware general partnership, as assignor, and
Mortgagor, as assignee and recorded on January 6, 1997 in the Office of the
Recorder of Deeds for New Castle County, Delaware in Deed Book 2219, Page 265.
<PAGE>

                                                    Tax Parcel No. 06-040.00-007

                                                      PREPARED BY AND RETURN TO:

                                                      Dean A. Stiffle, Esq.
                                                      Battle Fowler LLP
                                                      Park Avenue Tower
                                                      75 East 55th Street
                                                      New York, New York 10022

================================================================================

                     Brandywine Operating Partnership, L.P.,
                  a Delaware limited partnership, as Mortgagor

                                       and

                       NationsBank, N.A., not individually
                  but acting in its capacity as administrative
                    and documentation agent for the equal and
                        ratable benefit of the co-lenders
                         described herein, as Mortgagee

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

                                  AMENDMENT TO
                                    MORTGAGE
                           --------------------------

                           Dated: As of July 15, 1997

                           Location:  Delaware Corporate Center 1
                                      New Castle County
                                      Delaware
<PAGE>

================================================================================
<PAGE>

                                   Exhibit F-1

                                              Uniform Parcel Identifier: _______

                    OPEN-END MORTGAGE AND SECURITY AGREEMENT
                     (This Mortgage Secures Future Advances)

                  This Mortgage entered into as of the ___ day of July, 1997,
            between Brandywine Operating Partnership, L.P., a Delaware limited
            partnership having an office c/o Brandywine Realty Trust, Newtown
            Square Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown
            Square, Pennsylvania (hereinafter referred to as "Mortgagor"); and
            NationsBank, N.A., a national banking association having an office
            at 8300 Greensboro Drive, McLean, Virginia, not individually, but
            acting in its capacity as administrative and documentation agent for
            the equal and ratable benefit of Co-Lenders, pursuant to and in
            accordance with the terms and provisions of the Credit Agreement
            (NationsBank, N.A., acting in such capacity as administrative and
            documentation agent being hereinafter referred to as "Mortgagee").

                              PRELIMINARY STATEMENT

            A. All capitalized terms as used in this Mortgage shall, unless
otherwise defined in this Mortgage, have the meanings given to such terms in
Exhibit A attached hereto.

            B. Mortgagor is the owner of a fee estate in the premises described
in Exhibit B attached hereto (hereinafter referred to as the "Premises").

            C. Co-Lenders have on the terms, covenants and provisions set forth
in the Credit Agreement extended to Borrowers a revolving credit facility in the
principal sum of up to, but not in excess of, $150,000,000 (hereinafter referred
to as the "Credit Facility"), which Credit Facility is evidenced by, and payable
together with interest thereon in accordance with the provisions of, the Credit
Facility Notes.

            D. Co-Lenders have approved the inclusion of the Premises and the
Improvements as part of the collateral pool for the Credit Facility in
accordance with the provisions of the Credit Agreement, and in connection
therewith, and as consideration therefor, Mortgagor has agreed to execute and
deliver this Mortgage to Mortgagee, as administrative and documentation agent
for the equal and ratable benefit of Co-Lenders, as security for the payment of
the Debt.
<PAGE>

            E. NOW, THEREFORE, to secure the payment of an indebtedness in the
principal sum of up to, but not in excess of, One Hundred Fifty Million and
00/100 Dollars ($150,000,000.00), lawful money of the United States of America,
or so much thereof as may be advanced and readvanced and be outstanding from
time to time in accordance with the provisions of the Credit Agreement, to be
paid with interest in accordance with the provisions of the Credit Facility
Notes and the Credit Agreement (said indebtedness, interest and any and all sums
which may or shall become due in accordance with the provisions of the Credit
Facility Documents being hereinafter collectively referred to as the "Debt"),
Mortgagor has mortgaged, created a security interest in, given, granted,
bargained, sold, aliened, enfeoffed, conveyed, confirmed and assigned, and by
these presents does mortgage, create a security interest in, give, grant,
bargain, sell, alien, enfeoff, convey, confirm and assign unto Mortgagee forever
all right, title and interest of Mortgagor now owned, or hereafter acquired, in
and to the following property, rights and interests (such property, rights and
interests being hereinafter collectively referred to as the "Mortgaged
Property"):

            a. the Premises;

            b. all buildings and improvements now or hereafter located on the
      Premises (hereinafter referred collectively to as the "Improvements");

            c. all of the estate, right, title, claim or demand of any nature
      whatsoever of Mortgagor, either in law or in equity, in possession or
      expectancy, in and to the Mortgaged Property or any part thereof;

            d. all easements, rights-of-way, gores of land, streets, ways,
      alleys, passages, sewer rights, waters, water courses, water rights and
      powers, and all estates, rights, titles, interests, privileges, liberties,
      tenements, hereditaments, and appurtenances of any nature whatsoever, in
      any way belonging, relating or pertaining to the Mortgaged Property
      (including, without limitation, any and all development rights, air rights
      or similar or comparable rights of any nature whatsoever now or hereafter
      appurtenant to the Premises or now or hereafter transferred to the
      Premises) and all land lying in the bed of any street, road or avenue,
      opened or proposed, in front of or adjoining the Premises to the center
      line thereof;

            e. all FF&E and the right, title and interest of Mortgagor in and to
      any of the FF&E which may be subject to any security agreements (as
      defined in the Uniform Commercial Code) superior in lien to the lien of
      this Mortgage;

            f. all awards or payments, including interest thereon, if any, and
      the right to receive the same, which may be made with respect to the
      Mortgaged Property, whether from the exercise of the right of eminent
      domain (including any transfer made in lieu of the exercise of said
      right), or for any other injury to or decrease in the value of the
      Mortgaged Property;
<PAGE>

            g. all leases, licenses and other agreements affecting or relating
      to the use or occupancy of the Mortgaged Property now or hereafter entered
      into (such leases, licenses and other agreements are hereinafter
      collectively referred to as the "Leases") and the right to receive and
      apply the rents, income, revenues, receipts, accounts, accounts
      receivable, issues and profits of or derived from or relating to the
      Mortgaged Property (hereinafter collectively referred to as the "Rents")
      to the payment of the Debt;

            h. all proceeds of and any unearned premiums on any insurance
      policies covering the Mortgaged Property, including, without limitation,
      the right (subject to the provisions of the Credit Agreement) to receive
      and apply the proceeds of any insurance, judgments, or settlements made in
      lieu thereof, for damage to the Mortgaged Property; and

            i. the right to appear in and defend any action, case or proceeding
      brought with respect to the Mortgaged Property and to commence any action,
      case or proceeding to protect the interest of Mortgagee in the Mortgaged
      Property;

            TO HAVE AND TO HOLD the above granted and described Mortgaged
Property unto and to the proper use and benefit of Mortgagee, and the successors
and assigns of Mortgagee, forever;

            PROVIDED, HOWEVER, that if Mortgagor shall pay, perform and
discharge the obligations secured hereby in full, then this Mortgage and the
estate hereby granted shall cease, terminate and become void.

            AND Mortgagor covenants and agrees with and represents and warrants
to Mortgagee as follows:

            CLXXXV. Payment of Debt. Mortgagor will pay the Debt at the time and
in the manner provided for its payment in the Credit Facility Documents.

            CLXXXVI. Warranty of Title. Subject only to those exceptions to
title specifically set forth in the title policy issued or to be issued by the
Title Company to Mortgagee and insuring the lien of this Mortgage, Mortgagor
warrants the title to the Premises, the Improvements, the FF&E and the balance
of the Mortgaged Property.

            CLXXXVII. Leases and Rents. Subject to the terms of this paragraph,
Mortgagee waives the right to enter the Mortgaged Property for the purpose of
collecting the Rents, and grants Mortgagor the right to collect the Rents.
Mortgagor shall collect and hold the Rents, or an amount sufficient to discharge
all current sums due on the Debt, in trust for use in payment of the Debt. The
right of Mortgagor to collect the Rents may be revoked by Mortgagee upon the
occurrence of any Event of Default by giving notice of such revocation to
Mortgagor. Following such notice and as long as such Event of Default is
continuing (it being understood that the decision whether or not to accept the
cure of an Event of Default shall be in the sole and absolute discretion of
Mortgagee), Mortgagee may retain and apply the Rents toward payment of the Debt
in such order, priority and proportions as Mortgagee, in 
<PAGE>

its discretion, shall deem proper, or to the operation, maintenance and repair
of the Mortgaged Property, and irrespective of whether Mortgagee shall have
commenced a foreclosure of this Mortgage or shall have applied or arranged for
the appointment of a receiver. In addition, Mortgagee shall have the absolute
and unconditional right following the occurrence and during the continuance of
an Event of Default to notify the tenants under the Leases that all Rents should
be paid directly to Mortgagee. In addition to the rights which Mortgagee may
have herein, if an Event of Default shall occur and shall be continuing
Mortgagee, at its option, may require Mortgagor to pay monthly in advance to
Mortgagee, or any receiver appointed to collect the Rents, the fair and
reasonable rental value for the use and occupation of such part of the Mortgaged
Property as may be in possession of Mortgagor. Upon default in any such payment,
Mortgagor will vacate and surrender possession of the Mortgaged Property to
Mortgagee, or to such receiver and, in default thereof, Mortgagor may be evicted
by summary proceedings or otherwise. Nothing contained in this paragraph shall
be construed as imposing on Mortgagee any of the obligations of the landlord
under the Leases.

            CLXXXVIII. Notice. Any notice, request, demand, statement,
authorization, approval or consent made hereunder shall be in writing and shall
be sent by Federal Express, or other reputable national courier service, or by
postage pre-paid registered or certified mail, return receipt requested, and
shall be deemed given (i) when received at the following addresses if sent by
Federal Express, or other reputable national courier service, and (ii) three (3)
business days after being postmarked and addressed as follows if sent by
registered or certified mail, return receipt requested:
<PAGE>

            If to Mortgagor:

                  c/o Brandywine Realty Trust
                  Newtown Square Corporate Campus
                  16 Campus Boulevard, Suite 150
                  Newtown Square, Pennsylvania 19073
                  Attention:  Gerard H. Sweeney
                              President and Chief Executive Officer

            With a copy to:

                  Pepper, Hamilton & Scheetz
                  3000 Two Logan Square
                  Eighteenth and Arch Streets
                  Philadelphia, Pennsylvania 19103-2799
                  Attention:  Michael H. Friedman, Esq.

            If to Mortgagee:

                  NationsBank, N.A.
                  Real Estate Banking
                  8300 Greensboro Drive
                  McLean, Virginia 22102-3604
                  Attention:  Cheryl D. Fitzgerald
                              Vice President

            With copies to:

                  Cadwalader, Wickersham & Taft
                  201 South College Street - Suite 1510
                  Charlotte, North Carolina 28244
                  Attention:  James P. Carroll, Esq.

                              and

                  Battle Fowler LLP
                  Park Avenue Tower
                  75 East 55th Street
                  New York, New York 10022
                  Attention:  Dean A. Stiffle, Esq.

Each party may designate a change of address by notice to the other party, given
at least fifteen (15) days before such change of address is to become effective.

            CLXXXIX. Sale of Mortgaged Property. If this Mortgage is foreclosed,
the Mortgaged Property, or any interest therein, may, at the discretion of
Mortgagee, be sold in one or more parcels or in several interests or portions
and in any order or manner.

            CXC. Changes in Laws Regarding Taxation. In the event of the passage
after the date of this Mortgage of any law of the State in which the 
<PAGE>

Premises are located deducting from the value of real property for the purpose
of taxation any lien or encumbrance thereon or changing in any way the laws for
the taxation of mortgages or debts secured by mortgages for state or local
purposes or the manner of the collection of any such taxes, and imposing a tax,
either directly or indirectly, on this Mortgage, the Credit Facility Notes or
the Debt, Mortgagor shall, if permitted by law, pay any tax imposed as a result
of any such law within the statutory period or within thirty (30) days after
demand by Mortgagee, whichever is less, provided, however, that if, in the
opinion of the attorneys for Mortgagee, Mortgagor is not permitted by law to pay
such taxes, Mortgagee shall have the right, at its option, to declare the Debt
due and payable on a date specified in a prior notice to Mortgagor of not less
than sixty (60) days.

            CXCI. No Credits on Account of the Debt. Mortgagor will not claim or
demand or be entitled to any credit or credits on account of the Debt for any
part of the Taxes assessed against the Mortgaged Property or any part thereof
and no deduction shall otherwise be made or claimed from the taxable value of
the Mortgaged Property, or any part thereof, by reason of this Mortgage or the
Debt.

            CXCII. Documentary Stamps. If at any time the United States of
America, any state thereof, or any governmental subdivision of any such state,
shall require revenue or other stamps to be affixed to the Credit Facility Notes
(or any of them), this Mortgage or any of the other Credit Facility Documents,
Mortgagor will, to the extent permitted by law, pay for the same, with interest
and penalties thereon, if any.

            CXCIII. Events of Default. The Debt shall become due at the option
of Mortgagee upon the occurrence of any one or more of the Events of Default.

            CXCIV. Certain Remedies. Following the occurrence of any Event of
Default, Mortgagee shall have all rights and remedies provided pursuant to the
Credit Facility Documents, at law and in equity.

      A. Without limiting the generality of the foregoing, Mortgagee may:

                  1. Entry. Enter and take possession of Mortgaged Property or
            any part thereof, exclude Mortgagee and/or any lessee of any portion
            of the Mortgaged Property and all persons claiming under them wholly
            or partly therefrom, and operate, use, manage and control the same,
            or cause the same to be operated by a person selected by Mortgagee,
            either in the name of Mortgagor or otherwise, and upon such entry,
            from time to time, at the expense of Mortgagor, make all such
            repairs, replacements, alterations, additions or improvements
            thereto as Mortgagee may deem proper, and collect and receive the
            income therefrom and apply the same to the payment of all expenses
            which Mortgagee may be authorized to incur under the provisions of
            this Mortgage and the other Credit Facility Documents and applicable
            law, the remainder to be applied to the payment, performance and
            discharge of the obligations
<PAGE>

            secured hereby in such order, priority and proportion as Mortgagee
            may determine in the exercise of its sole and absolute discretion
            until the same have been paid in full.

                  2. Foreclosure. Institute an action for the foreclosure of
            this Mortgage and the sale of the Mortgaged Property pursuant to the
            judgment or decree of a court of competent jurisdiction.

                  3. Sale. Sell the Mortgaged Property at foreclosure to the
            highest bidder or bidders at public auction at sales held at such
            places and times and upon such notice and otherwise in such manner
            as may be required by law, or in the absence of any such
            requirement, as Mortgagee may deem appropriate, and from time to
            time adjourn such sale by announcement at the time and place
            specified for such sale or for such adjourned sale without further
            notice.

                  4. Specific Performance. Take all steps to protect and enforce
            the rights of Mortgagee under this Mortgage by suit for specific
            performance of any covenant herein contained, or in aid of the
            execution of any power herein granted or for the enforcement of any
            other rights.

            B. If Mortgagor fails or refuses to surrender possession of the
      Mortgaged Property after any sale thereof, Mortgagor shall be deemed a
      tenant at sufferance, subject to eviction by means of forcible entry and
      detainer proceedings, provided that this remedy is not exclusive or in
      derogation of any other right or remedy available to Mortgagee or any
      purchaser of the Mortgaged Property under any provision of this Mortgage
      or pursuant to any judgment or decree of court.

            C. FOR THE PURPOSES OF THE REMEDIES AFFORDED MORTGAGEE IN THIS
      MORTGAGE, MORTGAGOR HEREBY AUTHORIZES ANY ATTORNEY OF ANY COURT OF RECORD
      TO APPEAR FOR IT TO SIGN AN AGREEMENT FOR ENTERING AN AMICABLE ACTION OF
      EJECTMENT FOR POSSESSION OF ANY OF THE MORTGAGED PROPERTY AND TO CONFESS
      JUDGMENT THEREON AGAINST MORTGAGOR IN FAVOR OF MORTGAGEE, WHEREUPON A WRIT
      MAY FORTHWITH ISSUE FOR THE IMMEDIATE POSSESSION OF ANY OF THE MORTGAGED
      PROPERTY, WITHOUT ANY PRIOR WRIT OR PROCEEDING WHATSOEVER; AND FOR SO
      DOING, THIS MORTGAGE OR A COPY HEREOF VERIFIED BY AFFIDAVIT SHALL BE A
      SUFFICIENT WARRANT.

            D. Mortgagor hereby waives and releases all procedural errors,
      defects and imperfections in any proceedings instituted by Mortgagee under
      this Mortgage except for required notices under this Mortgage.

            CXCV. Appointment of Receiver. Mortgagee, in any action to foreclose
this Mortgage or upon the actual or threatened waste to any part of the
Mortgaged Property or upon the occurrence of any Event of Default, shall be at
liberty, without notice, to apply for the appointment of a receiver of the
Rents, and shall be entitled to the appointment of such receiver as a matter of
right, without regard to the value of the Mortgaged Property as 
<PAGE>

security for the Debt, or the solvency or insolvency of any person then liable
for the payment of the Debt.

            CXCVI. Non-Waiver. The failure of Mortgagee to insist upon strict
performance of any term of this Mortgage shall not be deemed to be a waiver of
any term of this Mortgage. Mortgagor shall not be relieved of Mortgagor's
obligation to pay the Debt at the time and in the manner provided for its
payment in the Credit Facility Documents by reason of (i) failure of Mortgagee
to comply with any request of Mortgagor to take any action to foreclose this
Mortgage or any other mortgage or deed of trust securing the Debt or any portion
thereof or otherwise enforce any of the provisions of this Mortgage or any of
the other Credit Facility Documents, (ii) the release, regardless of
consideration, of the whole or any part of the Mortgaged Property or any other
security for the Debt, or (iii) any agreement or stipulation between Mortgagee
and any subsequent owner or owners of the Mortgaged Property or other person
extending the time of payment or otherwise modifying or supplementing the terms
of the Credit Facility Documents without first having obtained the consent of
Mortgagor, and in the latter event, Mortgagor shall continue to be obligated to
pay the Debt at the times and in the manner provided in the Credit Facility
Documents, as so extended, modified and supplemented, unless expressly released
and discharged from such obligation by Mortgagee in writing. Regardless of
consideration, and without the necessity for any notice to or consent by the
holder of any subordinate lien, encumbrance, right, title or interest in or to
the Mortgaged Property, Mortgagee may release any person at any time liable for
the payment of the Debt or any portion thereof or any part of the security held
for the Debt and may extend the time of payment of the Debt or otherwise modify
the terms of the Credit Facility Documents, including, without limitation, a
modification of the interest rate payable on the Principal Balance of the Credit
Facility Notes, without in any manner impairing or affecting this Mortgage or
the lien thereof or the priority of this Mortgage, as so extended and modified,
as security for the Debt over any such subordinate lien, encumbrance, right,
title or interest. Mortgagee may resort for the payment of the Debt to any other
security held by Mortgagee in such order and manner as Mortgagee, in its
discretion, may elect. Mortgagee may take action to recover the Debt, or any
portion thereof, or to enforce any covenant hereof without prejudice to the
right of Mortgagee thereafter to foreclose this Mortgage. Mortgagee shall not be
limited exclusively to the rights and remedies herein stated but shall be
entitled to every additional right and remedy set forth in the Credit Facility
Documents or now or hereafter afforded by law. The rights of Mortgagee under
this Mortgage and the other Credit Facility Documents shall be separate,
distinct and cumulative and none shall be given effect to the exclusion of the
others. No act of Mortgagee shall be construed as an election to proceed under
any one provision of this Mortgage or of the other Credit Facility Documents to
the exclusion of any other provision set forth in this Mortgage or the other
Credit Facility Documents.

            CXCVII. Construction. The terms of this Mortgage shall be construed
in accordance with the laws of the State in which the Premises are located.
<PAGE>

            CXCVIII. Security Agreement. This Mortgage constitutes both a real
property mortgage and a "security agreement", within the meaning of the Uniform
Commercial Code, and the Mortgaged Property includes both real and personal
property and all other rights and interest, whether tangible or intangible in
nature, of Mortgagor in the Mortgaged Property. This Mortgage secures, and the
obligations secured hereby include, future advances. All advances and
indebtedness arising and accruing from time to time under the Credit Facility
shall be secured hereby to the same extent as though the Credit Agreement and
the other Credit Facility Documents were fully incorporated in this Mortgage.
Under the Credit Agreement and the other Credit Facility Documents advances may
be made and indebtedness may be incurred from time to time hereafter, but each
such advance or indebtedness shall be secured hereby as if made on the date
hereof. Mortgagor by executing and delivering this Mortgage has granted to
Mortgagee, as security for the Debt, a security interest in the Mortgaged
Property, including, without limitation, FF&E. This Mortgage constitutes and is
effective as a fixture filing as provided in Section 402 of Division 9 of the
Uniform Commercial Code, as to those portions of the Mortgaged Property are or
are to become fixtures as defined in the Uniform Commercial Code. If an Event of
Default shall occur, Mortgagee, in addition to any other rights and remedies
which it may have, shall have and may exercise immediately and without demand
any and all rights and remedies granted to a secured party upon default under
the Uniform Commercial Code, including, without limiting the generality of the
foregoing, the right to take possession of the FF&E or any part thereof, and to
take such other measures as Mortgagee may deem necessary for the care,
protection and preservation of the FF&E. Mortgagor shall pay to Mortgagee on
demand any and all expenses (including reasonable attorneys' fees) actually
incurred or paid by Mortgagee in protecting its interest in the FF&E and in
enforcing its rights hereunder with respect to the FF&E. Any notice of sale,
disposition or other intended action by Mortgagee with respect to the FF&E sent
to Mortgagor in accordance with the provisions of this Mortgage at least seven
(7) business days prior to the date of any such sale, disposition or other
action, shall constitute reasonable notice to Mortgagor (except in the case of
FF&E which is perishable or is of a type customarily sold on a recognized
market, in which case such seven (7) business days' notice shall not be
required), and the method of sale or disposition or other intended action set
forth or specified in such notice shall conclusively be deemed to be
commercially reasonable within the meaning of the Uniform Commercial Code unless
objected to in writing by Mortgagor within five (5) days after receipt by
Mortgagor of such notice. The proceeds of any sale or disposition of the FF&E,
or any part thereof, may be applied by Mortgagee to the payment of the Debt in
such order, priority and proportions as Mortgagee in its discretion shall deem
proper.

            CXCIX. Further Acts, etc. Mortgagor will, at the cost of Mortgagor,
and without expense to Mortgagee, do, execute, acknowledge and deliver all and
every such further acts, deeds, conveyances, mortgages, assignments, notices of
assignments, transfers and assurances as Mortgagee shall, from time to time,
require for the better assuring, conveying, assigning, transferring and
confirming unto Mortgagee the property and rights hereby mortgaged or intended
now or hereafter so to be, or which Mortgagor may be or may hereafter become
bound to convey or assign to Mortgagee, or for 
<PAGE>

carrying out the intention or facilitating the performance of the terms of this
Mortgage or for filing, registering or recording this Mortgage and, on demand,
will execute and deliver and hereby authorizes Mortgagee to execute in the name
of Mortgagor to the extent Mortgagee may lawfully do so, one or more financing
statements, chattel mortgages or comparable security instruments, to evidence
more effectively the lien hereof upon the Mortgaged Property.

            CC. Headings, etc. The headings, titles and captions of various
paragraphs of this Mortgage are for convenience of reference only and are not to
be construed as defining or limiting, in any way, the scope or intent of the
provisions hereof.

            CCI. Filing of Mortgage, etc. Mortgagor forthwith upon the execution
and delivery of this Mortgage and thereafter, from time to time, will cause this
Mortgage, and any security instrument creating a lien or evidencing the lien
hereof upon the Mortgaged Property and each instrument of further assurance to
be filed, registered or recorded in such manner and in such places as may be
required by any present or future law in order to publish notice of and fully to
protect, preserve and perfect the lien hereof upon, and the interest of
Mortgagee in, the Mortgaged Property. Mortgagor will pay all filing,
registration and recording fees, and all expenses incident to the preparation,
execution and acknowledgement of this Mortgage, any mortgage supplemental
hereto, any security instrument with respect to the Mortgaged Property, and any
instrument of further assurance, and all Federal, state, county and municipal
taxes, duties, imposts, assessments and charges arising out of or in connection
with the execution and delivery of this Mortgage, any mortgage supplemental
hereto, any security instrument with respect to the Mortgaged Property or any
instrument of further assurance. Mortgagor shall hold harmless and indemnify
Mortgagee, its successors and assigns, against any liability incurred by reason
of the imposition of any tax on the making and recording of this Mortgage.

            CCII. Recovery of Sums Required To Be Paid. Mortgagee shall have the
right from time to time to take action to recover any sum or sums which
constitute a part of the Debt as the same become due, without regard to whether
or not the balance of the Debt shall be due, and without prejudice to the right
of Mortgagee thereafter to bring an action of foreclosure, or any other action,
for a default or defaults by Mortgagor existing at the time such earlier action
was commenced.

            CCIII. Actions, Cases and Proceedings. Mortgagee shall have the
right to appear in and defend any action, case or proceeding brought with
respect to the Mortgaged Property and to bring any action, case or proceeding,
which Mortgagee, in its discretion, feels should be brought to protect its
interest in the Mortgaged Property.

            CCIV. Inapplicable Provisions. If any term, covenant or condition of
this Mortgage shall be held to be invalid, illegal or unenforceable in any
respect, this Mortgage shall be construed without such provision.
<PAGE>

            CCV. Duplicate Originals. This Mortgage may be executed in any
number of duplicate originals and each such duplicate original shall be deemed
to constitute but one and the same instrument.

            CCVI. Certain Usage. Unless the context clearly indicates a contrary
intent or unless otherwise specifically provided herein, words used in this
Mortgage shall be used interchangeably in singular or plural form. Whenever the
context may require, any pronouns used herein shall include the corresponding
masculine, feminine or neuter forms, and the singular forms of nouns and
pronouns shall include the plural and vice versa.

            CCVII. Waiver of Notice. Mortgagor shall not be entitled to any
notices of any nature whatsoever from Mortgagee except with respect to matters
for which this Mortgage specifically and expressly provides for the giving of
notice by Mortgagee to Mortgagor, and Mortgagor (to the full extent it may
lawfully do so) hereby expressly waives the right to receive any notice from
Mortgagee with respect to any matter for which this Mortgage does not
specifically and expressly provide for the giving of notice by Mortgagee to
Mortgagor.

            CCVIII. No Oral Change. This Mortgage may only be modified, amended
or changed by an agreement in writing signed by Mortgagor and Mortgagee, and may
only be released, discharged or satisfied of record by an agreement in writing
signed by Mortgagee. No waiver of any term, covenant or provision of this
Mortgage shall be effective unless given in writing by Mortgagee and if so given
by Mortgagee shall only be effective in the specific instance in which given.

            CCIX. Waiver of Statutory Rights. Mortgagor shall not and will not
apply for or avail itself of any appraisement, valuation, stay, extension or
exemption laws, or any so-called "Moratorium Laws", now existing or hereafter
enacted, in order to prevent or hinder the enforcement or foreclosure of this
Mortgage, but hereby waives the benefit of such laws to the full extent that
Mortgagor may do so under applicable law. Mortgagor for itself and all who may
claim through or under it waives any and all right to have the property and
estates comprising the Mortgaged Property marshalled upon any foreclosure of the
lien of this Mortgage and agrees that any court having jurisdiction to foreclose
such lien may order the Mortgaged Property sold as an entirety. Mortgagor hereby
waives for itself and all who may claim through or under it, and to the full
extent Mortgagor may do so under applicable law, any and all rights of
redemption from sale under any order or decree of foreclosure of this Mortgage
or granted under any statute now existing or hereafter enacted.

            CCX. Credit Agreement. This Mortgage is subject to all of the terms,
covenants and conditions of the Credit Agreement, which Credit Agreement and all
of the terms, covenants and conditions thereof are by this reference
incorporated herein with the same force and effect as if fully set forth herein.
The proceeds of the Credit Facility secured hereby are to be advanced and
readvanced by Mortgagee to Mortgagor in accordance with the provisions of the
Credit Agreement. Mortgagor shall observe and perform all of the terms,
covenants and conditions of the Credit Agreement on Mortgagor's 
<PAGE>

part to be observed or performed. All advances (including future advances) made
and all indebtedness arising and accruing under the Credit Agreement from time
to time shall constitute part of the Debt and shall be secured hereby as if made
on the date hereof.

            CCXI. Revolving Credit Facility. The Credit Facility is intended to
be a revolving credit facility. Mortgagor shall have the right upon compliance
with the conditions of the Credit Agreement and the other Credit Facility
Documents which pertain to the making of advances under the Credit Facility
(including, without limitation, the requirement that all advances be evidenced
and secured by the Credit Facility Documents and insured under acceptable title
insurance policies) to obtain readvances of amounts from time to time applied
(whether on a mandatory or voluntary basis) in reduction of the outstanding
Principal Balance of the Credit Facility pursuant to the provisions of the
Credit Agreement, or otherwise permitted to be made in accordance with the
provisions of the Credit Agreement or the other Credit Facility Documents
(including, without limitation, any portion of the outstanding Principal Balance
of the Credit Facility which is prepaid in accordance with the provisions of the
Credit Facility Notes and the Credit Agreement).

            CCXII. Binding Effect. The terms, covenants and provisions of this
Mortgage shall be binding on and shall inure to the benefit of Mortgagor,
Mortgagee, and their respective successors and assigns.

            CCXIII. Exculpation. No recourse shall be had for any obligation of
BRT under this Mortgage or any of the other Credit Facility Documents or for any
claim based thereon or otherwise in respect thereof, against any past, present
or future trustee, shareholder, officer or employee of BRT, 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 each
other party to this Mortgage and the other Credit Facility Documents.

            CCXIV. Open-End Mortgage. This Mortgage is an open-end mortgage
securing future advances pursuant to 42 Pa. C.S.A. ss.8143. Without limiting the
foregoing or any other provision of this Mortgage, this Mortgage secures, inter
alia, present and future advances of the Credit Facility made by Co-Lenders or
Mortgagee pursuant to the Credit Agreement and/or the other Credit Facility
Documents; advances made by Mortgagee or Co-Lenders with respect to the
Mortgaged Premises for the payment of taxes, assessments, maintenance charges,
insurance premiums or costs incurred for the protection of the Mortgaged
Premises or the lien of this Mortgage; and expenses incurred by Mortgagee or
Co-Lenders by reason of the occurrence of an Event of Default. The priority of
such future advances and expenses shall relate back to the date of this
Mortgage, or to such later date as required by applicable law, regardless of the
date upon which such advances are made or such expenses are incurred. If the
Credit Facility Documents provide that any advances of the Credit Facility shall
be made by Co-Lenders upon completion by Mortgagor of certain performance
obligations under the Credit Agreement and/or the other Credit Facility
Documents (including, without limitation, compliance with the terms of the
Credit Agreement and/or the other Credit Facility Documents such 
<PAGE>

that no default or Event of Default shall have occurred), such advances of the
Credit Facility shall be and be deemed "obligatory advances" solely for the
purpose of the application of the obligatory advance doctrine to confirm the
lien priority of such advances of the Credit Facility actually made by
Co-Lenders, whether such advances of the Credit Facility are initially either
(1) advanced by Co-Lenders or Mortgagee into an escrow subject to Mortgagee's or
Co-Lenders' control or (2) retained by Co-Lenders or Mortgagee.
<PAGE>

            IN WITNESS WHEREOF, Mortgagor has duly executed and delivered this
Mortgage as of the day and year first above written.

                                    BRANDYWINE OPERATING PARTNERSHIP, L.P., a
                                    Delaware limited partnership

                                    By:   Brandywine Realty Trust, a Maryland
                                          real estate investment trust

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

                    Certificate of Residence of the Mortgagee

            The business address of the Mortgagee herein is 8300 Greensboro
Drive, McLean, Virginia 22102-3604.

                                    
                                    ----------------------------
                                    Agent/Attorney for Mortgagee
<PAGE>

STATE OF _________)
                  )     ss:

COUNTY OF ________)

            On this, the ____ day of July, 1997, before me, a Notary Public, the
undersigned officer, personally appeared Gerard H. Sweeney, the President and
Chief Executive Officer of Brandywine Realty Trust, a Maryland real estate
investment trust, as general partner of Brandywine Operating Partnership, L.P.,
a Delaware limited partnership, known to me (or satisfactorily proven) to be the
person whose name is subscribed to the within instrument, and acknowledged that
he executed the same on behalf of the trust as general partner of the limited
partnership in the capacity therein stated and for the purposes therein
contained.

            IN WITNESS WHEREOF, I hereunto set my hand and Notarial seal.


                                        -------------------------
                                        Notary Public

[SEAL]

My Commission Expires:
<PAGE>

                                    EXHIBIT A

                                  (Definitions)

BMS:  The term "BMS" as used in this Mortgage shall mean Brandywine-Main
Street, LLC, a Delaware limited liability company.

BOP:  The term "BOP" as used in this Mortgage shall mean Brandywine Operating
Partnership, L.P., a Delaware limited partnership.

Borrowers:  The term "Borrowers" as used in this Mortgage shall collectively
mean BRT, BOP, BMS and the BRT/BOP Limited Partnerships.

BRT:  The term "BRT" as used in this Mortgage shall mean Brandywine Realty
Trust, a Maryland real estate investment trust.

BRT/BOP Limited Partnerships: The term "BRT/BOP Limited Partnerships" as used in
this Mortgage shall collectively mean LC/N Horsham Limited Partnership, a
Pennsylvania limited partnership; LC/N Keith Valley Limited Partnership I, a
Pennsylvania limited partnership; Nichols Lansdale Limited Partnership III, a
Pennsylvania limited partnership; Newtech III Limited Partnership, a
Pennsylvania limited partnership; Newtech IV Limited Partnership, a Pennsylvania
limited partnership; C/N Oaklands Limited Partnership I, a Pennsylvania limited
partnership; Fifteen Horsham, L.P., a Pennsylvania limited partnership; C/N
Leedom Limited Partnership II, a Pennsylvania limited partnership; C/N Iron Run
Limited Partnership III, a Pennsylvania limited partnership.

Co-Lenders: The term "Co-Lenders" as used in this Mortgage shall mean,
collectively, Smith Barney, NB The First National Bank of Chicago, a national
banking association, Mellon Bank, N.A., a national banking association, PNC
Bank, National Association, a national banking association, Signet Bank, a
____________________, Summit Bank, a ___________________ state banking
association, and all other parties from time to time to whom direct interests in
the Credit Facility are sold, transferred and assigned, and who are as a result
thereof designated as Co-Lenders, under and pursuant to the provisions of the
Credit Agreement and the Co-Lenders Agreement.

Co-Lenders Agreement: The term "Co-Lenders Agreement" as used in this Mortgage
shall mean that certain Co-Lender and Servicing Agreement dated as of November
25, 1996 between Smith Barney and NB, in its individual capacity and in its
capacity as administrative and documentation agent for the Credit Facility, as
the same may be modified, amended or supplemented from time to time.

Credit Agreement: The term "Credit Agreement" as used in this Mortgage shall
mean that certain Revolving Credit Agreement dated as of November 25, 1996 among
Smith Barney, NationsBank, N.A., in its individual capacity, Borrowers and NB,
acting in its capacity as administrative and documentation agent for the Credit
Facility, as the same may be amended from time to time, and 
<PAGE>

pursuant to the provisions of which the Credit Facility is being extended by
Co-Lenders to Mortgagor.

Credit Facility: The term "Credit Facility" as used in this Mortgage shall have
the meaning given to such term in paragraph C of the Preliminary Statement of
this Mortgage.

Credit Facility Documents: The term "Credit Facility Documents" as used in this
Mortgage shall have the meaning given to such term in the Credit Agreement.

Credit Facility Notes: The term "Credit Facility Notes" as used in this Mortgage
shall have the meaning given to such term in the Credit Agreement.

Debt: The term "Debt" as used in this Mortgage shall have the meaning given to
such term in paragraph E of the Preliminary Statement of this Mortgage.

Default Rate:  The term "Default Rate" as used in this Mortgage shall have
the meaning given to such term in the Credit Agreement.

Events of Default: The term "Events of Default" as used in this Mortgage shall
have the meaning given to such term in the Credit Agreement.

FF&E: The term "FF&E" as used in this Mortgage shall mean, collectively, all
goods (as such term is defined in the Uniform Commercial Code), now owned or
hereafter acquired by Mortgagor, located at or used in connection with the
Improvements and the operation of the Improvements, including, without
limitation, (i) all furniture and furnishings and all other items of personal
property (including inventory now owned or hereafter acquired by Mortgagor) now
and hereafter located on, or used in connection with the operation of the
Improvements, together with all replacements, modifications, alterations and
additions thereto; and (ii) all equipment, fixtures, machinery and other items
of property required or incidental to the use of the Improvements, including all
components thereof, now and hereafter permanently affixed to or incorporated
into the Improvements, including, without limitation, all furnaces, boilers,
heaters, electrical equipment, heating, plumbing, lighting, ventilating,
refrigerating, incineration, air and water pollution control, waste, disposal,
air-cooling and air conditioning systems and apparatus, sprinkler systems and
fire and theft protection equipment, together with all replacements,
modifications, alterations and additions thereto.

Improvements:  The term "Improvements" as used in this Mortgage shall have
the meaning given to such term in the granting clause of this Mortgage.

Leases:  The terms "Leases" as used in this Mortgage shall have the meaning
given to such term in the granting clause of this Mortgage.

Principal Balance:  The term "Principal Balance" as used in this Mortgage
shall have the meaning given to such term in the Credit Agreement.
<PAGE>

Mortgaged Property: The term "Mortgaged Property" as used in this Mortgage shall
have the meaning given to such term in the granting clause of this Mortgage.

Mortgagee:  The term "Mortgagee" as used in this Mortgage shall have the
meaning given to such term in the preamble to this Mortgage.

Mortgagor:  The term "Mortgagor" as used in this Mortgage shall have the
meaning given to such term in the preamble to this Mortgage.

NB:  The term "NB" as used in this Mortgage shall mean NationsBank, N.A., a
national banking association.

Premises: The term "Premises" as used in this Mortgage shall have the meaning
given to such term in paragraph B of the Preliminary Statement of this Mortgage.

Rents:  The term "Rents" as used in this Mortgage shall have the meaning
given to such term in the granting clause of this Mortgage.

Smith Barney:  The term "Smith Barney" as used in this Mortgage shall mean
Smith Barney Mortgage Capital Group, Inc., a Delaware corporation.

Taxes:  The term "Taxes" as used in this Mortgage shall have the meaning
given to such term in the Credit Agreement.

Title Company:  The term "Title Company" as used in this Mortgage shall have
the meaning given to such term in the Credit Agreement.

Uniform Commercial Code: The term "Uniform Commercial Code" as used in this
Mortgage shall mean the Uniform Commercial Code of the State in which the
Premises are located.
<PAGE>

                                   *EXHIBIT B

                            (Description of Premises)

- --------------
*     Legal description of premises should include insurable description of
      any easements which are appurtenant to the Premises.
<PAGE>

================================================================================

                     Brandywine Operating Partnership, L.P.,
                  a Delaware limited partnership, as Mortgagor

                                       to

                       NationsBank, N.A., not individually
                  but acting in its capacity as administrative

                    and documentation agent for the equal and
                        ratable benefit of the co-lenders

                         described herein, as Mortgagee


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

                    OPEN-END MORTGAGE AND SECURITY AGREEMENT
                     (This Mortgage Secures Future Advances)

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


                           Dated: As of July __, 1997

                          Location: __________________

                                    __________________

                                    __________________

                          RECORD AND RETURN TO:

                          Battle Fowler LLP
                          Park Avenue Tower
                          75 East 55th Street
                          New York, New York 10022

                          Attention:  Dean A. Stiffle, Esq.
<PAGE>

                          Uniform Parcel Identifier:  _______

================================================================================
                                                  Master Pennsylvania Mortgage
<PAGE>

                                TABLE OF CONTENTS
<PAGE>

                                                                            Page
                                                                            ----

1.  Payment of Debt........................................................  3

2.  Warranty of Title......................................................  3

3.  Leases and Rents.......................................................  3

4.  Notice.................................................................  4

5.  Sale of Mortgaged Property.............................................  5

6.  Changes in Laws Regarding Taxation.....................................  5

7.  No Credits on Account of the Debt......................................  5

8.  Documentary Stamps.....................................................  5

9.  Events of Default......................................................  7

10. Certain Remedies.......................................................  7

11.  Appointment of Receiver...............................................  8

12.  Non-Waiver............................................................  8

13.  Construction..........................................................  9

14.  Security Agreement....................................................  9

15.  Further Acts, etc.....................................................  9

16.  Headings, etc......................................................... 10

17.  Filing of Mortgage, etc............................................... 10

18.  Recovery of Sums Required To Be Paid.................................. 10

19.  Actions, Cases and Proceedings........................................ 10

20.  Inapplicable Provisions............................................... 10

21.  Duplicate Originals................................................... 10

22.  Certain Usage......................................................... 10

23.  Waiver of Notice...................................................... 10

24.  No Oral Change........................................................ 11
<PAGE>

25.  Waiver of Statutory Rights............................................ 11

26.  Credit Agreement...................................................... 11

27.  Revolving Credit Facility............................................. 11

28.  Binding Effect........................................................ 11

29.  Exculpation........................................................... 11

30.  Open-End Mortgage..................................................... 12

ACKNOWLEDGEMNT
EXHIBIT A - (Definitions)
EXHIBIT
<PAGE>

                                   Exhibit F-2

                                    MORTGAGE

                  This Mortgage entered into as of the ___ day of July, 1997,
      between Brandywine Operating Partnership, L.P., a Delaware limited
      partnership having an office c/o Brandywine Realty Trust, Newtown Square
      Corporate Campus, 16 Campus Boulevard, Suite 150, Newtown Square,
      Pennsylvania (hereinafter referred to as "Mortgagor"); and NationsBank,
      N.A., a national banking association having an office at 8300 Greensboro
      Drive, McLean, Virginia, not individually, but acting in its capacity as
      administrative and documentation agent for the equal and ratable benefit
      of Co-Lenders, pursuant to and in accordance with the terms and provisions
      of the Credit Agreement (NationsBank, N.A., acting in such capacity as
      administrative and documentation agent being hereinafter referred to as
      "Mortgagee").

                              PRELIMINARY STATEMENT

            A. All capitalized terms as used in this Mortgage shall, unless
otherwise defined in this Mortgage, have the meanings given to such terms in
Exhibit A attached hereto.

            B. Mortgagor is the owner of a fee estate in the premises described
in Exhibit B attached hereto (hereinafter referred to as the "Premises").

            C. Co-Lenders have on the terms, covenants and provisions set forth
in the Credit Agreement extended to Borrowers a revolving credit facility in the
principal sum of up to, but not in excess of, $150,000,000 (hereinafter referred
to as the "Credit Facility"), which Credit Facility is evidenced by, and payable
together with interest thereon in accordance with the provisions of, the Credit
Facility Notes.

            D. Co-Lenders have approved the inclusion of the Premises and the
Improvements as part of the collateral pool for the Credit Facility in
accordance with the provisions of the Credit Agreement, and in connection
therewith, and as consideration therefor, Mortgagor has agreed to execute and
deliver this Mortgage to Mortgagee, as administrative and documentation agent
for the equal and ratable benefit of Co-Lenders, as security for the payment of
the Debt.
<PAGE>

            E. NOW, THEREFORE, to secure the payment of an indebtedness in the
principal sum of up to, but not in excess of, One Hundred Fifty Million and
00/100 Dollars ($150,000,000.00), lawful money of the United States of America,
or so much thereof as may be advanced and readvanced and be outstanding from
time to time in accordance with the provisions of the Credit Agreement, to be
paid with interest in accordance with the provisions of the Credit Facility
Notes and the Credit Agreement (said indebtedness, interest and any and all sums
which may or shall become due in accordance with the provisions of the Credit
Facility Documents being hereinafter collectively referred to as the "Debt"),
Mortgagor has mortgaged, given, granted, bargained, sold, aliened, enfeoffed,
conveyed, confirmed and assigned, and by these presents does mortgage, give,
grant, bargain, sell, alien, enfeoff, convey, confirm and assign unto Mortgagee
forever all right, title and interest of Mortgagor now owned, or hereafter
acquired, in and to the following property, rights and interests (such property,
rights and interests being hereinafter collectively referred to as the
"Mortgaged Property"):

            (i) the Premises;

            (ii) all buildings and improvements now or hereafter located on the
      Premises (hereinafter referred collectively to as the "Improvements");

            (iii) all of the estate, right, title, claim or demand of any nature
      whatsoever of Mortgagor, either in law or in equity, in possession or
      expectancy, in and to the Mortgaged Property or any part thereof;

            (iv) all easements, rights-of-way, gores of land, streets, ways,
      alleys, passages, sewer rights, waters, water courses, water rights and
      powers, and all estates, rights, titles, interests, privileges, liberties,
      tenements, hereditaments, and appurtenances of any nature whatsoever, in
      any way belonging, relating or pertaining to the Mortgaged Property
      (including, without limitation, any and all development rights, air rights
      or similar or comparable rights of any nature whatsoever now or hereafter
      appurtenant to the Premises or now or hereafter transferred to the
      Premises) and all land lying in the bed of any street, road or avenue,
      opened or proposed, in front of or adjoining the Premises to the center
      line thereof;

            (v) all FF&E and the right, title and interest of Mortgagor in and
      to any of the FF&E which may be subject to any security agreements (as
      defined in the Uniform Commercial Code) superior in lien to the lien of
      this Mortgage;

            (vi) all awards or payments, including interest thereon, if any, and
      the right to receive the same, which may be made with respect to the
      Mortgaged Property, whether from the exercise of the right of eminent
<PAGE>

      domain (including any transfer made in lieu of the exercise of said
      right), or for any other injury to or decrease in the value of the
      Mortgaged Property;

            (vii) all leases, licenses and other agreements affecting or
      relating to the use or occupancy of the Mortgaged Property now or
      hereafter entered into (such leases, licenses and other agreements are
      hereinafter collectively referred to as the "Leases") and the right to
      receive and apply the rents, income, revenues, receipts, accounts,
      accounts receivable, issues and profits of or derived from or relating to
      the Mortgaged Property (hereinafter collectively referred to as the
      "Rents") to the payment of the Debt;

            (viii) all proceeds of and any unearned premiums on any insurance
      policies covering the Mortgaged Property, including, without limitation,
      the right (subject to the provisions of the Credit Agreement) to receive
      and apply the proceeds of any insurance, judgments, or settlements made in
      lieu thereof, for damage to the Mortgaged Property; and

            (ix) the right to appear in and defend any action, case or
      proceeding brought with respect to the Mortgaged Property and to commence
      any action, case or proceeding to protect the interest of Mortgagee in the
      Mortgaged Property;

            TO HAVE AND TO HOLD the above granted and described Mortgaged
Property unto and to the proper use and benefit of Mortgagee, and the successors
and assigns of Mortgagee, forever;

            AND Mortgagor covenants and agrees with and represents and warrants
to Mortgagee as follows:

            CCXV. Payment of Debt. Mortgagor will pay the Debt at the time and
in the manner provided for its payment in the Credit Facility Documents.

            CCXVI. Warranty of Title. Subject only to those exceptions to title
specifically set forth in the title policy issued or to be issued by the Title
Company to Mortgagee and insuring the lien of this Mortgage, Mortgagor warrants
the title to the Premises, the Improvements, the FF&E and the balance of the
Mortgaged Property.

            CCXVII. Leases and Rents. Subject to the terms of this paragraph,
Mortgagee waives the right to enter the Mortgaged Property for the purpose of
collecting the Rents, and grants Mortgagor the right to collect the Rents.
Mortgagor shall collect and hold the Rents, or an amount sufficient to discharge
all current sums due on the Debt, in trust for use in payment of the Debt. The
right of Mortgagor to collect the Rents may be revoked by Mortgagee upon the
occurrence of any Event of Default by giving notice of such revocation to
Mortgagor. Following such notice and as long as such Event of 
<PAGE>

Default is continuing (it being understood that the decision whether or not to
accept the cure of an Event of Default shall be in the sole and absolute
discretion of Mortgagee), Mortgagee may retain and apply the Rents toward
payment of the Debt in such order, priority and proportions as Mortgagee, in its
discretion, shall deem proper, or to the operation, maintenance and repair of
the Mortgaged Property, and irrespective of whether Mortgagee shall have
commenced a foreclosure of this Mortgage or shall have applied or arranged for
the appointment of a receiver. In addition, Mortgagee shall have the absolute
and unconditional right following the occurrence and during the continuance of
an Event of Default to notify the tenants under the Leases that all Rents should
be paid directly to Mortgagee. In addition to the rights which Mortgagee may
have herein, if an Event of Default shall occur and shall be continuing
Mortgagee, at its option, may require Mortgagor to pay monthly in advance to
Mortgagee, or any receiver appointed to collect the Rents, the fair and
reasonable rental value for the use and occupation of such part of the Mortgaged
Property as may be in possession of Mortgagor. Upon default in any such payment,
Mortgagor will vacate and surrender possession of the Mortgaged Property to
Mortgagee, or to such receiver and, in default thereof, Mortgagor may be evicted
by summary proceedings or otherwise. Nothing contained in this paragraph shall
be construed as imposing on Mortgagee any of the obligations of the landlord
under the Leases.

            CCXVIII. Notice. Any notice, request, demand, statement,
authorization, approval or consent made hereunder shall be in writing and shall
be sent by Federal Express, or other reputable national courier service, or by
postage pre-paid registered or certified mail, return receipt requested, and
shall be deemed given (i) when received at the following addresses if sent by
Federal Express, or other reputable national courier service, and (ii) three (3)
business days after being postmarked and addressed as follows if sent by
registered or certified mail, return receipt requested:
<PAGE>

            If to Mortgagor:

                  c/o Brandywine Realty Trust
                  Newtown Square Corporate Campus
                  16 Campus Boulevard, Suite 150
                  Newtown Square, Pennsylvania 19073
                  Attention:  Gerard H. Sweeney
                              President and Chief Executive Officer

            With a copy to:

                  Pepper, Hamilton & Scheetz
                  3000 Two Logan Square
                  Eighteenth and Arch Streets
                  Philadelphia, Pennsylvania 19103-2799
                  Attention:  Michael H. Friedman, Esq.

            If to Mortgagee:

                  NationsBank, N.A.
                  Real Estate Banking
                  8300 Greensboro Drive
                  McLean, Virginia 22102-3604
                  Attention:  Cheryl D. Fitzgerald
                              Vice President

            With copies to:

                  Cadwalader, Wickersham & Taft
                  201 South College Street - Suite 1510
                  Charlotte, North Carolina 28244
                  Attention:  James P. Carroll, Esq.

                              and

                  Battle Fowler LLP
                  Park Avenue Tower
                  75 East 55th Street
                  New York, New York 10022
                  Attention:  Dean A. Stiffle, Esq.

Each party may designate a change of address by notice to the other party, given
at least fifteen (15) days before such change of address is to become effective.

            CCXIX. Sale of Mortgaged Property. If this Mortgage is foreclosed,
the Mortgaged Property, or any interest therein, may, at the 
<PAGE>

discretion of Mortgagee, be sold in one or more parcels or in several interests
or portions and in any order or manner.

            CCXX. Changes in Laws Regarding Taxation. In the event of the
passage after the date of this Mortgage of any law of the State in which the
Premises are located deducting from the value of real property for the purpose
of taxation any lien or encumbrance thereon or changing in any way the laws for
the taxation of mortgages or debts secured by mortgages for state or local
purposes or the manner of the collection of any such taxes, and imposing a tax,
either directly or indirectly, on this Mortgage, the Credit Facility Notes or
the Debt, Mortgagor shall, if permitted by law, pay any tax imposed as a result
of any such law within the statutory period or within thirty (30) days after
demand by Mortgagee, whichever is less, provided, however, that if, in the
opinion of the attorneys for Mortgagee, Mortgagor is not permitted by law to pay
such taxes, Mortgagee shall have the right, at its option, to declare the Debt
due and payable on a date specified in a prior notice to Mortgagor of not less
than sixty (60) days.

            CCXXI. No Credits on Account of the Debt. Mortgagor will not claim
or demand or be entitled to any credit or credits on account of the Debt for any
part of the Taxes assessed against the Mortgaged Property or any part thereof
and no deduction shall otherwise be made or claimed from the taxable value of
the Mortgaged Property, or any part thereof, by reason of this Mortgage or the
Debt.

            CCXXII. Documentary Stamps. If at any time the United States of
America, any state thereof, or any governmental subdivision of any such state,
shall require revenue or other stamps to be affixed to the Credit Facility Notes
(or any of them), this Mortgage or any of the other Credit Facility Documents,
Mortgagor will, to the extent permitted by law, pay for the same, with interest
and penalties thereon, if any.

            CCXXIII. Events of Default. The Debt shall become due at the option
of Mortgagee upon the occurrence of any one or more of the Events of Default.

            CCXXIV. Appointment of Receiver. Mortgagee, in any action to
foreclose this Mortgage or upon the actual or threatened waste to any part of
the Mortgaged Property or upon the occurrence of any Event of Default, shall be
at liberty, without notice, to apply for the appointment of a receiver of the
Rents, and shall be entitled to the appointment of such receiver as a matter of
right, without regard to the value of the Mortgaged Property as security for the
Debt, or the solvency or insolvency of any person then liable for the payment of
the Debt.

            CCXXV. Non-Waiver. The failure of Mortgagee to insist upon strict
performance of any term of this Mortgage shall not be deemed to be a waiver of
any term of this Mortgage. Mortgagor shall not be relieved of 
<PAGE>

Mortgagor's obligation to pay the Debt at the time and in the manner provided
for its payment in the Credit Facility Documents by reason of (i) failure of
Mortgagee to comply with any request of Mortgagor to take any action to
foreclose this Mortgage or any other mortgage or deed of trust securing the Debt
or any portion thereof or otherwise enforce any of the provisions of this
Mortgage or any of the other Credit Facility Documents, (ii) the release,
regardless of consideration, of the whole or any part of the Mortgaged Property
or any other security for the Debt, or (iii) any agreement or stipulation
between Mortgagee and any subsequent owner or owners of the Mortgaged Property
or other person extending the time of payment or otherwise modifying or
supplementing the terms of the Credit Facility Documents without first having
obtained the consent of Mortgagor, and in the latter event, Mortgagor shall
continue to be obligated to pay the Debt at the times and in the manner provided
in the Credit Facility Documents, as so extended, modified and supplemented,
unless expressly released and discharged from such obligation by Mortgagee in
writing. Regardless of consideration, and without the necessity for any notice
to or consent by the holder of any subordinate lien, encumbrance, right, title
or interest in or to the Mortgaged Property, Mortgagee may release any person at
any time liable for the payment of the Debt or any portion thereof or any part
of the security held for the Debt and may extend the time of payment of the Debt
or otherwise modify the terms of the Credit Facility Documents, including,
without limitation, a modification of the interest rate payable on the Principal
Balance of the Credit Facility Notes, without in any manner impairing or
affecting this Mortgage or the lien thereof or the priority of this Mortgage, as
so extended and modified, as security for the Debt over any such subordinate
lien, encumbrance, right, title or interest. Mortgagee may resort for the
payment of the Debt to any other security held by Mortgagee in such order and
manner as Mortgagee, in its discretion, may elect. Mortgagee may take action to
recover the Debt, or any portion thereof, or to enforce any covenant hereof
without prejudice to the right of Mortgagee thereafter to foreclose this
Mortgage. Mortgagee shall not be limited exclusively to the rights and remedies
herein stated but shall be entitled to every additional right and remedy set
forth in the Credit Facility Documents or now or hereafter afforded by law. The
rights of Mortgagee under this Mortgage and the other Credit Facility Documents
shall be separate, distinct and cumulative and none shall be given effect to the
exclusion of the others. No act of Mortgagee shall be construed as an election
to proceed under any one provision of this Mortgage or of the other Credit
Facility Documents to the exclusion of any other provision set forth in this
Mortgage or the other Credit Facility Documents.

            CCXXVI. Construction. The terms of this Mortgage shall be construed
in accordance with the laws of the State in which the Premises are located.

            CCXXVII. Security Agreement. This Mortgage constitutes both a real
property mortgage and a "security agreement", within the meaning of the Uniform
Commercial Code, and the Mortgaged Property includes both real and
<PAGE>

personal property and all other rights and interest, whether tangible or
intangible in nature, of Mortgagor in the Mortgaged Property. Mortgagor by
executing and delivering this Mortgage has granted to Mortgagee, as security for
the Debt, a security interest in the Mortgaged Property, including, without
limitation, FF&E. If an Event of Default shall occur, Mortgagee, in addition to
any other rights and remedies which it may have, shall have and may exercise
immediately and without demand any and all rights and remedies granted to a
secured party upon default under the Uniform Commercial Code, including, without
limiting the generality of the foregoing, the right to take possession of the
FF&E or any part thereof, and to take such other measures as Mortgagee may deem
necessary for the care, protection and preservation of the FF&E. Mortgagor shall
pay to Mortgagee on demand any and all expenses (including reasonable attorneys'
fees) actually incurred or paid by Mortgagee in protecting its interest in the
FF&E and in enforcing its rights hereunder with respect to the FF&E. Any notice
of sale, disposition or other intended action by Mortgagee with respect to the
FF&E sent to Mortgagor in accordance with the provisions of this Mortgage at
least seven (7) business days prior to the date of any such sale, disposition or
other action, shall constitute reasonable notice to Mortgagor (except in the
case of FF&E which is perishable or is of a type customarily sold on a
recognized market, in which case such seven (7) business days' notice shall not
be required), and the method of sale or disposition or other intended action set
forth or specified in such notice shall conclusively be deemed to be
commercially reasonable within the meaning of the Uniform Commercial Code unless
objected to in writing by Mortgagor within five (5) days after receipt by
Mortgagor of such notice. The proceeds of any sale or disposition of the FF&E,
or any part thereof, may be applied by Mortgagee to the payment of the Debt in
such order, priority and proportions as Mortgagee in its discretion shall deem
proper.

            CCXXVIII. Further Acts, etc. Mortgagor will, at the cost of
Mortgagor, and without expense to Mortgagee, do, execute, acknowledge and
deliver all and every such further acts, deeds, conveyances, mortgages,
assignments, notices of assignments, transfers and assurances as Mortgagee
shall, from time to time, require for the better assuring, conveying, assigning,
transferring and confirming unto Mortgagee the property and rights hereby
mortgaged or intended now or hereafter so to be, or which Mortgagor may be or
may hereafter become bound to convey or assign to Mortgagee, or for carrying out
the intention or facilitating the performance of the terms of this Mortgage or
for filing, registering or recording this Mortgage and, on demand, will execute
and deliver and hereby authorizes Mortgagee to execute in the name of Mortgagor
to the extent Mortgagee may lawfully do so, one or more financing statements,
chattel mortgages or comparable security instruments, to evidence more
effectively the lien hereof upon the Mortgaged Property.

            CCXXIX. Headings, etc. The headings, titles and captions of various
paragraphs of this Mortgage are for convenience of reference only and are not to
be construed as defining or limiting, in any way, the scope or intent of the
provisions hereof.
<PAGE>

            CCXXX. Filing of Mortgage, etc. Mortgagor forthwith upon the
execution and delivery of this Mortgage and thereafter, from time to time, will
cause this Mortgage, and any security instrument creating a lien or evidencing
the lien hereof upon the Mortgaged Property and each instrument of further
assurance to be filed, registered or recorded in such manner and in such places
as may be required by any present or future law in order to publish notice of
and fully to protect, preserve and perfect the lien hereof upon, and the
interest of Mortgagee in, the Mortgaged Property. Mortgagor will pay all filing,
registration and recording fees, and all expenses incident to the preparation,
execution and acknowledgement of this Mortgage, any mortgage supplemental
hereto, any security instrument with respect to the Mortgaged Property, and any
instrument of further assurance, and all Federal, state, county and municipal
taxes, duties, imposts, assessments and charges arising out of or in connection
with the execution and delivery of this Mortgage, any mortgage supplemental
hereto, any security instrument with respect to the Mortgaged Property or any
instrument of further assurance. Mortgagor shall hold harmless and indemnify
Mortgagee, its successors and assigns, against any liability incurred by reason
of the imposition of any tax on the making and recording of this Mortgage.

            CCXXXI. Recovery of Sums Required To Be Paid. Mortgagee shall have
the right from time to time to take action to recover any sum or sums which
constitute a part of the Debt as the same become due, without regard to whether
or not the balance of the Debt shall be due, and without prejudice to the right
of Mortgagee thereafter to bring an action of foreclosure, or any other action,
for a default or defaults by Mortgagor existing at the time such earlier action
was commenced.

            CCXXXII. Actions, Cases and Proceedings. Mortgagee shall have the
right to appear in and defend any action, case or proceeding brought with
respect to the Mortgaged Property and to bring any action, case or proceeding,
which Mortgagee, in its discretion, feels should be brought to protect its
interest in the Mortgaged Property.

            CCXXXIII. Inapplicable Provisions. If any term, covenant or
condition of this Mortgage shall be held to be invalid, illegal or unenforceable
in any respect, this Mortgage shall be construed without such provision.

            CCXXXIV. Duplicate Originals. This Mortgage may be executed in any
number of duplicate originals and each such duplicate original shall be deemed
to constitute but one and the same instrument.

            CCXXXV. Certain Usage. Unless the context clearly indicates a
contrary intent or unless otherwise specifically provided herein, words used in
this Mortgage shall be used interchangeably in singular or plural form. Whenever
the context may require, any pronouns used herein shall include the
<PAGE>

corresponding masculine, feminine or neuter forms, and the singular forms of
nouns and pronouns shall include the plural and vice versa.

            CCXXXVI. Waiver of Notice. Mortgagor shall not be entitled to any
notices of any nature whatsoever from Mortgagee except with respect to matters
for which this Mortgage specifically and expressly provides for the giving of
notice by Mortgagee to Mortgagor, and Mortgagor (to the full extent it may
lawfully do so) hereby expressly waives the right to receive any notice from
Mortgagee with respect to any matter for which this Mortgage does not
specifically and expressly provide for the giving of notice by Mortgagee to
Mortgagor.

            CCXXXVII. No Oral Change. This Mortgage may only be modified,
amended or changed by an agreement in writing signed by Mortgagor and Mortgagee,
and may only be released, discharged or satisfied of record by an agreement in
writing signed by Mortgagee. No waiver of any term, covenant or provision of
this Mortgage shall be effective unless given in writing by Mortgagee and if so
given by Mortgagee shall only be effective in the specific instance in which
given.

            CCXXXVIII. Waiver of Statutory Rights. Mortgagor shall not and will
not apply for or avail itself of any appraisement, valuation, stay, extension or
exemption laws, or any so-called "Moratorium Laws", now existing or hereafter
enacted, in order to prevent or hinder the enforcement or foreclosure of this
Mortgage, but hereby waives the benefit of such laws to the full extent that
Mortgagor may do so under applicable law. Mortgagor for itself and all who may
claim through or under it waives any and all right to have the property and
estates comprising the Mortgaged Property marshalled upon any foreclosure of the
lien of this Mortgage and agrees that any court having jurisdiction to foreclose
such lien may order the Mortgaged Property sold as an entirety. Mortgagor hereby
waives for itself and all who may claim through or under it, and to the full
extent Mortgagor may do so under applicable law, any and all rights of
redemption from sale under any order or decree of foreclosure of this Mortgage
or granted under any statute now existing or hereafter enacted.

            CCXXXIX. Credit Agreement. This Mortgage is subject to all of the
terms, covenants and conditions of the Credit Agreement, which Credit Agreement
and all of the terms, covenants and conditions thereof are by this reference
incorporated herein with the same force and effect as if fully set forth herein.
The proceeds of the Credit Facility secured hereby are to be advanced and
readvanced by Mortgagee to Mortgagor in accordance with the provisions of the
Credit Agreement. Mortgagor shall observe and perform all of the terms,
covenants and conditions of the Credit Agreement on Mortgagor's part to be
observed or performed. All advances made and all indebtedness arising and
accruing under the Credit Agreement from time to time shall constitute part of
the Debt and shall be secured hereby.
<PAGE>

            CCXL. Revolving Credit Facility. The Credit Facility is intended to
be a revolving credit facility. Mortgagor shall have the right upon compliance
with the conditions of the Credit Agreement and the other Credit Facility
Documents which pertain to the making of advances under the Credit Facility
(including, without limitation, the requirement that all advances be evidenced
and secured by the Credit Facility Documents and insured under acceptable title
insurance policies) to obtain readvances of amounts from time to time applied
(whether on a mandatory or voluntary basis) in reduction of the outstanding
Principal Balance of the Credit Facility pursuant to the provisions of the
Credit Agreement, or otherwise permitted to be made in accordance with the
provisions of the Credit Agreement or the other Credit Facility Documents
(including, without limitation, any portion of the outstanding Principal Balance
of the Credit Facility which is prepaid in accordance with the provisions of the
Credit Facility Notes and the Credit Agreement).

            CCXLI. Binding Effect. The terms, covenants and provisions of this
Mortgage shall be binding on and shall inure to the benefit of Mortgagor,
Mortgagee, and their respective successors and assigns.

            CCXLII. Exculpation. No recourse shall be had for any obligation of
BRT under this Mortgage or any of the other Credit Facility Documents or for any
claim based thereon or otherwise in respect thereof, against any past, present
or future trustee, shareholder, officer or employee of BRT, 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 each
other party to this Mortgage and the other Credit Facility Documents.

            IN WITNESS WHEREOF, Mortgagor has duly executed and delivered this
Mortgage as of the day and year first above written.

                                    BRANDYWINE OPERATING PARTNERSHIP, L.P., a
                                    Delaware limited partnership

                                    By:   Brandywine Realty Trust, a Maryland
                                          real estate investment trust

                                          By:  /s/ Gerard H. Sweeney
                                             ----------------------------------
                                             Name:   Gerard H. Sweeney
                                             Title:  President and Chief
                                                     Executive Officer
<PAGE>

STATE OF _________)
                  )  ss.

COUNTY OF ________)

            I CERTIFY, that on July __, 1997, Gerard H. Sweeney, personally came
before me and this person acknowledged under oath, to my satisfaction, that:

            (a) this person signed, sealed and delivered the attached document
            as President and Chief Executive Officer of Brandywine Realty Trust,
            a Maryland real estate investment trust, and that Brandywine Realty
            Trust is the General Partner of Brandywine Operating Partnership,
            L.P., a Delaware limited partnership, the partnership named in this
            document;

            (b) this document was signed and made by the real estate investment
            trust as its voluntary act and deed by virtue of authority from its
            Board of Trustees, as general partner of and on behalf of the
            aforementioned limited partnership.

                                             -----------------------
                                             Notary Public

      My Commission Expires:
<PAGE>

                                    EXHIBIT A

                                  (Definitions)

BMS: The term "BMS" as used in this Mortgage shall mean Brandywine - Main
Street, LLC, a Delaware limited liability company.

BOP:  The term "BOP" as used in this Mortgage shall mean Brandywine Operating
Partnership, L.P., a Delaware limited partnership.

Borrowers:  The term "Borrowers" as used in this Mortgage shall collectively
mean BRT, BOP, BMS and the BRT/BOP Limited Partnerships.

BRT:  The term "BRT" as used in this Mortgage shall mean Brandywine Realty
Trust, a Maryland real estate investment trust.

BRT/BOP Limited Partnerships: The term "BRT/BOP Limited Partnerships" as used in
this Mortgage shall collectively mean LC/N Horsham Limited Partnership, a
Pennsylvania limited partnership; LC/N Keith Valley Limited Partnership I, a
Pennsylvania limited partnership; Nichols Lansdale Limited Partnership III, a
Pennsylvania limited partnership; Newtech III Limited Partnership, a
Pennsylvania limited partnership; Newtech IV Limited Partnership, a Pennsylvania
limited partnership; C/N Oaklands Limited Partnership I, a Pennsylvania limited
partnership; Fifteen Horsham, L.P., a Pennsylvania limited partnership; C/N
Leedom Limited Partnership II, a Pennsylvania limited partnership; C/N Iron Run
Limited Partnership III, a Pennsylvania limited partnership.

Co-Lenders: The term "Co-Lenders" as used in this Mortgage shall mean,
collectively, Smith Barney, NB, The First National Bank of Chicago, a national
banking association, Mellon Bank, N.A., a national banking association, PNC
Bank, National Association, a national banking association, Signet Bank, a
_______________ and Summit Bank, a ______________ banking association and all
other parties from time to time to whom direct interests in the Credit Facility
are sold, transferred and assigned, and who are as a result thereof designated
as Co-Lenders, under and pursuant to the provisions of the Credit Agreement and
the Co-Lenders Agreement.

Co-Lenders Agreement: The term "Co-Lenders Agreement" as used in this Mortgage
shall mean that certain Co-Lender and Servicing Agreement dated as of November
25, 1996 between Smith Barney and NB, in its individual capacity and in its
capacity as administrative and documentation agent for the Credit Facility, as
the same may be modified, amended or supplemented from time to time.

Credit Agreement: The term "Credit Agreement" as used in this Mortgage shall
mean that certain Revolving Credit Agreement dated as of November 25, 1996 among
Smith Barney, NationsBank, N.A., in its individual capacity, Borrowers 
<PAGE>

and NB, acting in its capacity as administrative and documentation agent for the
Credit Facility, as the same may be amended from time to time, and pursuant to
the provisions of which the Credit Facility is being extended by Co-Lenders to
Mortgagor.

Credit Facility: The term "Credit Facility" as used in this Mortgage shall have
the meaning given to such term in paragraph C of the Preliminary Statement of
this Mortgage.

Credit Facility Documents: The term "Credit Facility Documents" as used in this
Mortgage shall have the meaning given to such term in the Credit Agreement.

Credit Facility Notes: The term "Credit Facility Notes" as used in this Mortgage
shall have the meaning given to such term in the Credit Agreement.

Debt: The term "Debt" as used in this Mortgage shall have the meaning given to
such term in paragraph E of the Preliminary Statement of this Mortgage.

Default Rate:  The term "Default Rate" as used in this Mortgage shall have
the meaning given to such term in the Credit Agreement.

Events of Default: The term "Events of Default" as used in this Mortgage shall
have the meaning given to such term in the Credit Agreement.

FF&E: The term "FF&E" as used in this Mortgage shall mean, collectively, all
goods (as such term is defined in the Uniform Commercial Code), now owned or
hereafter acquired by Mortgagor, located at or used in connection with the
Improvements and the operation of the Improvements, including, without
limitation, (i) all furniture and furnishings and all other items of personal
property (including inventory now owned or hereafter acquired by Mortgagor) now
and hereafter located on, or used in connection with the operation of the
Improvements, together with all replacements, modifications, alterations and
additions thereto; and (ii) all equipment, fixtures, machinery and other items
of property required or incidental to the use of the Improvements, including all
components thereof, now and hereafter permanently affixed to or incorporated
into the Improvements, including, without limitation, all furnaces, boilers,
heaters, electrical equipment, heating, plumbing, lighting, ventilating,
refrigerating, incineration, air and water pollution control, waste, disposal,
air-cooling and air conditioning systems and apparatus, sprinkler systems and
fire and theft protection equipment, together with all replacements,
modifications, alterations and additions thereto.

Improvements:  The term "Improvements" as used in this Mortgage shall have
the meaning given to such term in the granting clause of this Mortgage.

Leases:  The terms "Leases" as used in this Mortgage shall have the meaning
given to such term in the granting clause of this Mortgage.
<PAGE>

Principal Balance:  The term "Principal Balance" as used in this Mortgage
shall have the meaning given to such term in the Credit Agreement.

Mortgaged Property: The term "Mortgaged Property" as used in this Mortgage shall
have the meaning given to such term in the granting clause of this Mortgage.

Mortgagee:  The term "Mortgagee" as used in this Mortgage shall have the
meaning given to such term in the preamble to this Mortgage.

Mortgagor:  The term "Mortgagor" as used in this Mortgage shall have the
meaning given to such term in the preamble to this Mortgage.

NB:  The term "NB" as used in this Mortgage shall mean NationsBank, N.A., a
national banking association.

Premises: The term "Premises" as used in this Mortgage shall have the meaning
given to such term in paragraph B of the Preliminary Statement of this Mortgage.

Rents:  The term "Rents" as used in this Mortgage shall have the meaning
given to such term in the granting clause of this Mortgage.

Smith Barney:  The term "Smith Barney" as used in this Mortgage shall mean
Smith Barney Mortgage Capital Group, Inc., a Delaware corporation.

Taxes:  The term "Taxes" as used in this Mortgage shall have the meaning
given to such term in the Credit Agreement.

Title Company:  The term "Title Company" as used in this Mortgage shall have
the meaning given to such term in the Credit Agreement.

Uniform Commercial Code: The term "Uniform Commercial Code" as used in this
Mortgage shall mean the Uniform Commercial Code of the State in which the
Premises are located.
<PAGE>

                                   *EXHIBIT B

                            (Description of Premises)

- --------------
*     Legal description of premises should include insurable description of
      any easements which are appurtenant to the Premises.
<PAGE>

================================================================================

                     Brandywine Operating Partnership, L.P.,
                  a Delaware limited partnership, as Mortgagor

                                       to

                       NationsBank, N.A., not individually
                  but acting in its capacity as administrative
                    and documentation agent for the equal and
                        ratable benefit of the co-lenders
                         described herein, as Mortgagee


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

                                    MORTGAGE

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


                           Dated: As of July __, 1997

                           Location:   __________________
                                       _______ County, New Jersey

                           RECORD AND RETURN TO:

                           Battle Fowler LLP
                           Park Avenue Tower
                           75 East 55th Street
                           New York, New York 10022

                           Attention:  Dean A. Stiffle, Esq.
<PAGE>

THIS MORTGAGE WAS PREPARED BY:


- ------------------------------
Attorney at Law


================================================================================
                                                    Master New Jersey Mortgage
<PAGE>

                                TABLE OF CONTENTS

                                                                            Page
                                                                            ----

1.  Payment of Debt........................................................  3

2.  Warranty of Title......................................................  3

3.  Leases and Rents.......................................................  3

4.  Notice.................................................................  4

5.  Sale of Mortgaged Property.............................................  5

6.  Changes in Laws Regarding Taxation.....................................  5

7.  No Credits on Account of the Debt......................................  5

8.  Documentary Stamps.....................................................  5

9.  Events of Default......................................................  7

10.  Appointment of Receiver...............................................  7

11.  Non-Waiver............................................................  7

12.  Construction..........................................................  8

13.  Security Agreement....................................................  8

14.  Further Acts, etc.....................................................  8

15.  Headings, etc.........................................................  9

16.  Filing of Mortgage, etc...............................................  9

17.  Recovery of Sums Required To Be Paid..................................  9

18.  Actions, Cases and Proceedings........................................  9

19.  Inapplicable Provisions...............................................  9

20.  Duplicate Originals...................................................  9

21.  Certain Usage.........................................................  9

22.  Waiver of Notice......................................................  9

23.  No Oral Change........................................................ 10
<PAGE>

24.  Waiver of Statutory Rights............................................ 10

25.  Credit Agreement...................................................... 10

26.  Revolving Credit Facility............................................. 10

27.  Binding Effect........................................................ 11

28.  Exculpation........................................................... 11

ACKNOWLEDGEMENT

EXHIBIT A         (Definitions)
EXHIBIT B         (Description of Premises)
<PAGE>

                                    Exhibit G

================================================================================

                    Brandywine Operating Partnership, L.P.,
                  a Delaware limited partnership, as Assignor

                                      and

                   NationsBank, N.A., not individually, but 
                   acting in its capacity as collateral agent
                   for the equal and ratable benefit of the 
                   co-lenders described herein, as Assignee


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

                        ASSIGNMENT OF LEASES AND RENTS

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


                           Dated: As of July 15, 1997

                           Location:   __________________
                                       __________________
                                       __________________
 
                           RECORD AND RETURN TO:

                                Battle Fowler LLP
                                Park Avenue Tower
                                75 East 55th Street
                                New York, New York 10022
<PAGE>

                           Attention: Dean A. Stiffle, Esq.

================================================================================
                                                   MASTER ASSIGNMENT OF LEASES


                        ASSIGNMENT OF LEASES AND RENTS

                        This Assignment of Leases and Rents entered into as of
            the 15th day of July, 1997, by Brandywine Operating Partnership,
            L.P., a Delaware limited partnership having an office at c/o
            Brandywine Realty Trust, Newtown Square Corporate Campus, 16 Campus
            Boulevard, Suite 150, Newtown Square, Pennsylvania (hereinafter
            referred to as "Assignor"); and NationsBank, N.A., a national
            banking association having an office at 8300 Greensboro Drive,
            McLean, Virginia, not individually, but acting in its capacity as
            administrative and documentation agent for the equal and ratable
            benefit of Co-Lenders pursuant to and in accordance with the terms
            and provisions of the Credit Agreement (NationsBank, N.A. acting in
            such capacity as administrative and documentation agent being
            hereinafter referred to as "Assignee").

                              PRELIMINARY STATEMENT

            CCXLIII. All capitalized terms as used in this Assignment shall,
unless otherwise defined in this Assignment, have the meanings given to such
terms in Exhibit A attached hereto.

            CCXLIV. Assignor is the owner of a fee estate in the premises
described in Exhibit B attached hereto (hereinafter referred to as the
"Premises");

            CCXLV. Co-Lenders have on the terms, covenants and provisions set
forth in the Credit Agreement extended to Borrowers a revolving credit facility
in the principal sum of up to, but not in excess of, $150,000,000 (hereinafter
referred to as the "Credit Facility"), which Credit Facility is evidenced by,
and payable together with interest thereon in accordance with the provisions of,
the Credit Facility Notes.
<PAGE>

            D. Co-Lenders have approved the inclusion of the Premises as part of
the collateral pool for the Credit Facility in accordance with the provisions of
the Credit Agreement, and in connection therewith, and as consideration
therefor, Assignor has agreed to assign to Assignee, for the equal and ratable
benefit of Co-Lenders, in the manner hereinafter provided, as additional
security for the payment of the Debt and the observance and performance by
Borrowers of all of the terms, covenants and provisions of the Credit Facility
Documents on Borrowers' part to be observed and performed, all right, title and
interest of Assignor now owned, or hereafter acquired, in and to (i) all leases,
licenses and other agreements (hereinafter collectively referred to as the
"Leases") now or hereafter entered into and affecting or relating to the use or
occupancy of the Premises or of the improvements now or hereafter erected
thereon (the "Improvements"), and (ii) the rents, income, revenues, receipts,
accounts, accounts receivable, issues and profits of or derived from or relating
to the Premises or the Improvements or any portion thereof (hereinafter
collectively referred to as the "Rents").

            CCXLVI. NOW, THEREFORE, in consideration of the extension of the
Credit Facility and other good and valuable consideration, the receipt of which
is hereby acknowledged, Assignor hereby assigns to Assignee, as additional
security for the payment of the Debt and the observance and performance by
Borrowers of all of the terms, covenants and provisions of the Credit Facility
Documents on Borrowers' part to be observed or performed, all of Assignor's
right, title and interest now owned, or hereafter acquired, in and to the Leases
and the Rents, and Assignor hereby represents and warrants to and covenants and
agrees with Assignee as follows:

            A. Except as expressly set forth to the contrary in the certified
rent roll for the Property being delivered by Assignor to Assignee in connection
with the execution and delivery of this Assignment, Assignor represents and
warrants that as of the date hereof (i) Assignor is the owner and holder of the
landlord's interest under the Leases, (ii) there are no prior or subordinate
assignments of the Leases or of any portion of the Rents due and payable or to
become due and payable thereunder which are presently outstanding, (iii) all of
the Leases are in full force and effect and the respective terms thereof have
commenced pursuant to the provisions thereof, (iv) the premises demised under
each of the Leases have been completed and the tenants under the Leases have
taken possession of the premises demised thereunder on a rent-paying basis, (v)
neither Assignor nor any tenant under the Leases is in default under any of the
terms, covenants or provisions of the Leases and Assignor knows of no event
which, but for the passage of time or the giving of notice or both, would
constitute an event of default under any of the Leases, (vi) neither Assignor
nor any tenant under the Leases has commenced any action or given or served any
notice for the purpose of terminating any of the Leases, (vii) all Rents due and
payable under the Leases have been paid in full and no such Rents have been paid
more than one (l) month in advance of the due dates thereof, and (viii) there
are no offsets or defenses to the payment of any portion of the Rents.
<PAGE>

            B. Assignor shall, at its sole cost and expense, (i) fulfill and
perform, or cause to be fulfilled and performed, each and every term, covenant
and provision of the Leases on the part of the Assignor thereunder to be
observed and performed, (ii) promptly send copies of all notices of default
which Assignor shall send or receive under the Leases to Assignee, (iii) enforce
the observance and performance of the terms and provisions of the Leases by the
tenants thereunder, (iv) enforce the observance and performance of each and
every term, covenant and provision of the Leases on the part of the tenants
thereunder to be observed and performed and (v) appear in and defend any action
or proceeding arising under or in any manner connected with the Leases or with
the obligations and undertakings of the landlord or the tenants thereunder.

            C. Assignor shall not, without the prior consent of Co-Lenders, (i)
further transfer, sell, assign, pledge, encumber or grant a security interest in
all or any portion of the Rents or the Leases, (ii) accept prepayments of
installments of the Rents for a period of more than one (1) month in advance,
(iii) make or suffer to be made any Lease, including any renewal of an existing
Lease (other than renewals at rents and/on other terms expressly reserved in
such Lease) other than in accordance and in a manner consistent with the
provisions of the Credit Agreement, (iv) consent to or permit the assignment or
subletting of any leasehold estate created under any Lease (other than in
accordance with the express provisions of such Lease), (v) terminate, modify or
amend, or consent to the termination, modification or amendment of, any Lease or
any term thereof other than in accordance and in a manner consistent with the
provisions of the Credit Agreement, (vi) commence or continue proceedings to
evict, remove or dispossess the tenant under any Lease, provided, however, that
Assignor may commence and continue such a proceeding without obtaining the prior
consent of Assignor if the Lease in question does not cover in excess of 20,000
square feet of space in the Improvements and the commencement of such proceeding
is otherwise consistent with customary business practices for the operation of
improvements which are comparable to the Improvements, or (vii) waive, cancel,
release, modify, excuse, condone, set-off, compromise or in any manner release
or discharge the tenant under any Lease other than in a manner which is
consistent with customary business practices for the operation of improvements
comparable to the Improvements.

            D. This Assignment shall not be deemed or construed to obligate
Assignee or any Co-Lender to take any action or incur any expense or perform or
discharge any obligation, duty or liability under the Leases, and Assignor
hereby agrees to indemnify and hold Assignee and Co-Lenders harmless from and
against all liability, loss or damage, including, but not limited to, reasonable
attorneys' fees, which Assignee or any Co-Lender may or might incur under the
Leases or under or by reason of this Assignment and from and against any and all
claims whatsoever which may be asserted against Assignee or any Co-Lender by
reason of any alleged obligation or undertaking on the part of Assignee or any
Co-Lender to perform or discharge any of the terms, covenants or provisions
contained in the Leases.
<PAGE>

            E. This Assignment has been made as additional security for the
payment of the Debt and the observance and performance by Borrowers of the
terms, covenants and provisions of the Credit Facility Documents on Borrowers'
part to be observed and performed. Subject to the provisions of this Assignment
hereinafter set forth, Assignee waives the right to enter the Premises for the
purpose of collecting the Rents, and grants Assignor the right to collect the
Rents. Assignor shall collect and hold the Rents, or an amount sufficient to
discharge all current sums due on the Debt, in trust for use in the payment of
the Debt. The right of Assignor to collect the Rents may be revoked by Assignee
upon the occurrence of any Event of Default, by giving notice of such revocation
to Assignor. Following such notice and as long as such Event of Default is
continuing (it being understood that the decision whether or not to accept the
cure of an Event of Default shall be in the sole and absolute discretion of
Assignee), Assignee may retain and apply the Rents toward payment of the Debt in
such order, priority and proportions as Assignee in its discretion, shall deem
proper, or to the operation, maintenance and repair of the Property, and
irrespective of whether Assignee shall have declared the Debt to be immediately
due and payable, or shall have commenced a foreclosure of the Mortgage or shall
have applied or arranged for the appointment of a receiver. In addition,
Assignee shall have the absolute and unconditional right following the
occurrence and during the continuance of an Event of Default, to notify the
tenants under the Leases that all Rents should be paid directly to Assignee.
Upon the occurrence and during the continuance of an Event of Default, the
tenants under the Leases shall, upon notice from Assignee of the occurrence of
such Event of Default, thereafter pay to Assignee or to any appointed receiver
the Rents due or to become due under the Leases without any obligation to
determine whether or not such Event of Default does in fact exist, and Assignor
shall facilitate in all reasonable ways the collection of the Rents by Assignee,
and without implying the necessity therefor will, upon demand of Assignee,
execute written notices to the tenants under the Leases directing the tenants
under the Leases to pay the Rents to Assignee, which Rents may, during the
continuance of such Event of Default, be retained and applied by Assignee toward
the payment of the Debt in such order, priority and proportions as Assignee in
its discretion, shall deem proper, or to the operation, maintenance and repair
of the Property.

            F. Upon the occurrence of an Event of Default and for so long as
such Event of Default continues Assignee shall have the right, at its option, to
enter upon and take over and assume the management, operation and maintenance of
the Property and to perform all necessary and proper acts and to expend such
sums out of the income of the Property as may be necessary in connection
therewith, in the same manner and to the same extent as Assignor theretofore
might do, including the right to effect new Leases, cancel or surrender the
Leases, alter, modify or amend the provisions thereof, or make concessions to
the tenants thereunder and Assignor hereby releases and waives all claims
against Assignee arising out of such management, operation and maintenance.
Assignor shall, from time to time, at its expense, execute, deliver, file and
record any statement, assignment, instrument, document, agreement or other paper
and take any other action (including any filings of financing or continuation
statements under the Uniform Commercial Code) that 
<PAGE>

from time to time may be necessary or desirable, or that Assignee may reasonable
request, in order to create, preserve, perfect, confirm or validate the
assignment of the Leases and Rents made pursuant to the provisions of this
Assignment or to enable Assignee to obtain the full benefits of this Assignment,
or to enable Assignee to exercise and enforce any of its rights, powers and
remedies hereunder. To the extent permitted by applicable law, Assignor hereby
authorizes Assignee, and appoints Assignee as its true and lawful attorney (with
full power of substitution, in the name of Assignor), to execute and file
financing statements or continuation statements without Assignor's signature
appearing thereon.

            G. Nothing contained in this Assignment, and no entry by Assignee
upon the Property as hereinabove provided, shall be construed as to constitute
Assignee as a mortgagee in possession.

            H. Nothing contained in this Assignment is intended or shall be
construed to prevent Assignee in the exercise of its discretion from foreclosing
the Mortgage or otherwise enforcing the provisions thereof or of any of the
other Credit Facility Documents, in whole or in part, in accordance with their
terms.

            I. No alteration, extension, renewal, change, modification, release,
amendment, compromise or cancellation, in whole or in part, of any term,
covenant or provision of any of the other Credit Facility Documents shall affect
this Assignment in any manner or diminish or release any of the rights of
Assignee hereunder.

            J. Assignor hereby waives any and all legal requirements that
Assignee institute any action or proceeding in law or in equity against any
other party, or exhaust its remedies under any of the other Credit Facility
Documents as a condition precedent to exercising its rights and remedies under
this Assignment. All remedies afforded to Assignee by reason of this Assignment
are separate and cumulative remedies and it is agreed that no one of such
remedies whether exercised by Assignee or not, shall be deemed to be in
exclusion of any of the other remedies available to Assignee and shall not in
any manner limit or prejudice any other legal or equitable remedies which
Assignee may have, including, but not limited to, all rights and remedies of
Assignee under any of the other Credit Facility Documents.

            K. It is the intention of the parties hereto that any and all other
Leases affecting the Property or any portion thereof presently in effect or
hereafter entered into by Assignor or in which Assignor shall otherwise have an
interest shall be covered by the provisions of this Assignment and all such
Leases and all of Assignor's right, title and interest in all such Leases, and
the rents, additional rents, charges, issues, profits and other sums payable
thereunder, are hereby assigned to Assignee until the end of the respective
terms thereof and any renewals or extensions thereof, subject to all of the
terms, covenants and provisions of this Assignment. Assignor shall deliver a
true and correct copy of each such Lease to Assignee promptly after the
execution and delivery of the same. Assignor shall, upon the request of
<PAGE>

Assignee, execute and deliver in recordable form all instruments which Assignee
may reasonably request to further evidence and confirm such assignment of each
such Lease.

            L. This Assignment shall be binding upon Assignor, and its
successors and assigns and shall inure to the benefit of Assignee, and its
successors and assigns.

            M. This Assignment may only be modified, altered, amended, or
terminated by an agreement in writing executed by the parties hereto.

            N. Any notice, request, demand, statement or consent made hereunder
or in connection herewith shall be in writing and shall be sent in the manner
specified in the Credit Agreement.

            O. If any term, covenant or condition of this Assignment shall be
held to be invalid, illegal or unenforceable in any respect, this Assignment
shall be construed without such provision.

            P. This Assignment shall be governed by and construed under the laws
of the State in which the Property is located.

            18. No recourse shall be had for any obligation of BRT under this
Assignment or any of the other Credit Facility Documents or for any claim based
thereon or otherwise in respect thereof, against any past, present or future
trustee, shareholder, officer or employee of BRT, 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 each other
party to this Assignment and the other Credit Facility Documents.
<PAGE>

            IN WITNESS WHEREOF, Assignor has duly executed this Assignment as of
the day and year first above written.

                                    BRANDYWINE OPERATING PARTNERSHIP, L.P., a
                                    Delaware limited partnership

                                    By:   Brandywine Realty Trust, a Maryland
                                          real estate investment trust


                                          By:  /s/ Gerard H. Sweeney
                                             ----------------------------------
                                             Name:   Gerard H. Sweeney
                                             Title:  President and Chief
                                                      Executive Officer
<PAGE>

                                 ACKNOWLEDGMENTS

                                (To be attached)
<PAGE>

                                    EXHIBIT A
                                  (Definitions)

Assignee:  The term "Assignee" as used in this Assignment shall have the
meaning given to such term in the preamble to this Agreement.

Assignor:  The term "Assignor" as used in this Assignment shall have the
meaning given to such term in the preamble to this Agreement.

Approved Leasing Parameters: The term "Approved Leasing Parameters" as used in
this Assignment shall have the meaning given to such term in the Credit
Agreement.

BMS: The term "BMS" as used in this Agreement shall mean Brandywine - Main
Street, LLC, a Delaware limited liability company.

BOP:  The term "BOP" as used in this Agreement shall mean Brandywine
Operating Partnership, L.P., a Delaware limited partnership.

Borrowers:  The term "Borrowers" as used in this Assignment shall
collectively mean BRT, BOP, BMS and the BRT/BOP Limited Partnerships.

BRT:  The term "BRT" as used in this Assignment shall mean Brandywine Realty
Trust, a Maryland real estate investment trust.

BRT/BOP Limited Partnerships: The term "BRT/BOP Limited Partnerships" as used in
this Assignment shall mean LC/N Horsham Limited Partnership, a Pennsylvania
limited partnership; LC/N Keith Valley Limited Partnership I, a Pennsylvania
limited partnership; Nichols Lansdale Limited Partnership III, a Pennsylvania
limited partnership; Newtech III Limited Partnership, a Pennsylvania limited
partnership; Newtech IV Limited Partnership, a Pennsylvania limited partnership;
C/N Oaklands Limited Partnership I, a Pennsylvania limited partnership; Fifteen
Horsham, L.P., a Pennsylvania limited partnership; C/N Leedom Limited
Partnership II, a Pennsylvania limited partnership; C/N Iron Run Limited
Partnership III, a Pennsylvania limited partnership.

Co-Lenders: The term "Co-Lenders" as used in this Assignment shall collectively
mean, Smith Barney Mortgage Capital Group, Inc., and NationsBank, N.A., acting
in its individual capacity, The First National Bank of Chicago, a national
banking association, Mellon Bank, N.A., a national banking association, PNC
Bank, National Association, a national banking association, Signet Bank, a state
banking association organized under the laws of the Commonwealth of Virginia and
Summit Bank, a state banking association organized under the laws of the State
of New Jersey, and all other parties from time to time to whom direct interests
in the Credit Facility are sold, transferred and assigned, and who are as a
result thereof are designated as Co-Lenders under and pursuant to the provisions
of the Credit Agreement and the Co-Lenders Agreement.
<PAGE>

Co-Lenders Agreement: The term "Co-Lenders Agreement" as used in this Assignment
shall mean that certain Co-Lender and Servicing Agreement dated as of November
25, 1996 among Smith Barney Mortgage Capital Group, Inc., NationsBank, N.A.,
acting in its individual capacity, and NationsBank, N.A., acting in its capacity
as administrative and documentation agent for the equal and ratable benefit of
Co-Lenders in accordance with the provisions of the Credit Agreement, as the
same may be further modified, amended or supplemented from time to time.

Credit Agreement: The term "Credit Agreement" as used in this Assignment shall
mean that certain Revolving Credit Agreement dated as of November 25, 1996 among
Smith Barney Mortgage Capital Group, Inc., NationsBank, N.A., acting in its
individual capacity, Borrowers and NationsBank, N.A., acting in its capacity as
administrative and documentation agent for the equal and ratable benefit of
Co-Lenders, as the same may be amended from time to time, and pursuant to the
provisions of which the Credit Facility is being extended by Co-Lenders to
Borrowers.

Credit Facility: The term "Credit Facility" as used in this Assignment shall
have the meaning given to such term in paragraph C of the Preliminary Statement
of this Assignment.

Credit Facility Notes: The term "Credit Facility Notes" as used in this
Assignment shall have the meaning given to such term in the Credit Agreement.

Credit Facility Documents: The term "Credit Facility Documents" as used in this
Assignment shall have the meaning given to such term in the Credit Agreement.

Debt:  The term "Debt" as used in this Assignment shall have the meaning
given to such term in the Credit Agreement.

Event of Default: The term "Event of Default" as used in this Assignment shall
have the meaning given to such term in the Credit Agreement.

Improvements: The term "Improvements" as used in this Assignment shall have the
meaning given to such term in paragraph D of the Preliminary Statement of this
Assignment.

Leases: The term "Leases" as used in this Assignment shall have the meaning
given to such term in paragraph D of the Preliminary Statement of this
Assignment.

Mortgage: The term "Mortgage" as used in this Assignment shall mean that certain
Mortgage dated as of the date hereof given by Assignor to Assignee , as security
for the payment of the Debt and the observance and performance by Borrowers of
the terms, covenants and provisions of the Credit Facility Document on
Borrowers' part to be observed and performed, and encumbering 
<PAGE>

Assignor's right, title and interest in and to the Property and intended to be
duly recorded in __________County, __________.

Property:  The term "Property" as used in this Assignment shall collectively
mean the Premises and the Improvements.

Premises: The term "Premises" as used in this Assignment shall have the meaning
given to such term in paragraph B of the Preliminary Statement of this
Assignment.

Rents: The term "Rents" as used in this Assignment shall have the meaning given
to such term in paragraph D of the Preliminary Statement of this Assignment.

                                    EXHIBIT B



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