Document:

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                                                                   Exhibit 10.56

                                 LOAN AGREEMENT

     This Loan Agreement is entered into as of February 18, 2000 by and between
Gerard H. Sweeney ("Executive") and Brandywine Operating Partnership, L.P.
("Company").

     Intending to be legally bound, Executive and Company agree as follows:

          1. LOAN. On the date hereof, Company shall loan to Executive $1.5
     million (the "Loan").

          2. USE OF PROCEEDS; NO SECURITY. Executive agrees to use the proceeds
     of the Loan solely to purchase common shares of beneficial interest
     ("Common Shares") of Brandywine Realty Trust ("BRT") from Company. The
     obligations of Executive under this Agreement are unsecured, and, without
     limiting the generality of the foregoing, Executive and Company agree that
     Executive's obligations under this Agreement are not secured by a pledge of
     the Common Shares.

          3. INTEREST. Interest shall accrue on the outstanding principal
     balance of the Loan from the date hereof at a variable rate equal to the
     lower of: (i) the interest rate borne by Company's then outstanding
     revolving credit facility (as refinanced from time to time), (ii) the
     Dividend-Computed Rate (as defined below) and (iii) 10%. If borrowings
     under the revolving credit facility bear interest at different rates (e.g.,
     prime rate versus LIBOR), the applicable rate will be the highest of the
     rates in effect from time to time. The "Dividend Computed Rate" shall mean
     the rate, expressed as a percentage, computed as follows: FIRST, multiply
     by four the most recent regular quarterly dividend paid on a Common Share;
     SECOND, multiply the result from the first step by the number of Common
     Shares purchased with the Loan proceeds; THIRD, divide the result from the
     second step by the original principal amount of the Loan. For purposes of
     the foregoing, if the amount of the quarterly dividend changes, the
     Dividend Computed Rate will change, effective as of the payment date for
     such new dividend level. Accrued interest on the principal balance of the
     Loan shall be payable annually on the first business day of each April,
     commencing April 2001.

          4. MATURITY DATE. Subject to Section 6, the outstanding principal
     balance of the Loan, plus accrued but unpaid interest thereon, shall be due
     and payable on the first business day of April 2004.

          5. MANNER OF PAYMENT. The principal of, and interest on, the Loan
     shall be payable at Company's office at 14 Campus Boulevard, Suite 100,
     Newtown Square, Pennsylvania 19073 (or such other address as Company shall,
     from time to time, notify Executive). All such principal and interest shall
     be payable in lawful money of the United States of America in immediately
     available funds; provided, however, that Executive may, in his sole
     discretion, tender Common Shares to Company in repayment of all or any
     portion of the Loan and accrued interest thereon, with each share tendered
     valued at $15.625 (subject to equitable

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     and proportionate adjustment in the event of a split or reverse split of,
     or share dividend on, the Common Shares).

     6. LOAN FORGIVENESS.

          a. Upon a Change of Control of BRT, the outstanding principal balance
     of the Loan, plus accrued but unpaid interest thereon, shall automatically
     be forgiven. As used herein, the term "Change of Control" shall have the
     meaning assigned to it in the Amended and Restated Employment Agreement
     (the "Employment Agreement") between BRT and Executive.

          b. Within thirty (30) days following the first business day of each
     April 2001, 2002 and 2003, Company shall compute the total shareholder
     return on the Common Shares from February 18, 2000 through such first
     business day of April, and shall compare such total shareholder return to
     the total shareholder return over the same time period on the common shares
     of the other companies in the Peer Group (as defined below). If BRT's total
     shareholder return for each applicable period falls in the bottom quadrant
     of the Peer Group, then 25% of one-third of the original principal amount
     of the Loan shall be automatically forgiven as of such computation date. If
     BRT's total shareholder return falls in the third, second or first quadrant
     of the Peer Group, then 50%, 75% or 100%, respectively, of one third of the
     original principal amount of the Loan shall be automatically forgiven as of
     the computation date.

          c. In addition to the forgiveness provided in the preceding paragraph,
     if BRT's total shareholder return for any of the three measurement periods
     specified in the preceding paragraph exceeds the average total shareholder
     return of the companies in the first quadrant of the Peer Group for any
     such measurement period, then any portion of the principal of the Loan that
     was previously eligible for forgiveness, but which was not forgiven, shall
     be automatically forgiven.

          d. Whenever a portion of the principal of the Loan is forgiven,
     accrued interest on such portion of the principal shall also be forgiven.

          e. The Peer Group shall initially consist of the following companies,
     in addition to BRT: Koger Equity Inc., SL Green Realty Corp., Kilroy Realty
     Corp., Prentiss Properties Trust, Reckson Associates Realty Corp., First
     Industry Realty Trust Inc., Arden Realty Inc., CarrAmerica Realty Corp.,
     Highwoods Properties Inc., Mack-Cali Realty Corp., Bedford Properties,
     Liberty Property Trust and Great Lakes. In the event that any of such
     companies is involved in a business combination or similar extraordinary
     transaction, it shall be removed from the Peer Group.

     7. TREATMENT OF LOAN. For purposes of the "three times multiplier"
referenced in Sections 18(b) and (d) of the Employment Agreement, the amount of
the Loan and any portion of the Loan that is forgiven shall not be treated as an
amount paid to Executive
                                      -2-

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pursuant to Section 5 of the Employment Agreement and shall not be treated as
the short-term portion of any bonus amounts paid or payable to Executive
pursuant to Section 6 of the Employment Agreement.

     8. MISCELLANEOUS. This Agreement may be amended only by a written
instrument executed by Company and Executive. This Agreement shall be governed
by the laws of the State of Delaware.

     IN WITNESS WHEREOF, the parties have executed this Agreement as of the day
and year first above written.

                                     Brandywine Realty Trust

                                     By:_____________________________

                                     Title:__________________________

                                     _______________________________
                                             Gerard H. Sweeney

                                      -3-<PAGE>

                                                                   Exhibit 10.57

                                 LOAN AGREEMENT

     This Loan Agreement is entered into as of February 18, 2000 by and between
Anthony A. Nichols, Sr. ("Executive") and Brandywine Operating Partnership, L.P.
("Company").

     Intending to be legally bound, Executive and Company agree as follows:

          1. LOAN. On the date hereof, Company shall loan to Executive $1.0
     million (the "Loan").

          2. USE OF PROCEEDS; NO SECURITY. Executive agrees to use the proceeds
     of the Loan solely to purchase common shares of beneficial interest
     ("Common Shares") of Brandywine Realty Trust ("BRT") from Company. The
     obligations of Executive under this Agreement are unsecured, and, without
     limiting the generality of the foregoing, Executive and Company agree that
     Executive's obligations under this Agreement are not secured by a pledge of
     the Common Shares.

          3. INTEREST. Interest shall accrue on the outstanding principal
     balance of the Loan from the date hereof at a variable rate equal to the
     lower of: (i) the interest rate borne by Company's then outstanding
     revolving credit facility (as refinanced from time to time), (ii) the
     Dividend-Computed Rate (as defined below) and (iii) 10%. If borrowings
     under the revolving credit facility bear interest at different rates (e.g.,
     prime rate versus LIBOR), the applicable rate will be the highest of the
     rates in effect from time to time. The "Dividend Computed Rate" shall mean
     the rate, expressed as a percentage, computed as follows: FIRST, multiply
     by four the most recent regular quarterly dividend paid on a Common Share;
     SECOND, multiply the result from the first step by the number of Common
     Shares purchased with the Loan proceeds; THIRD, divide the result from the
     second step by the original principal amount of the Loan. For purposes of
     the foregoing, if the amount of the quarterly dividend changes, the
     Dividend Computed Rate will change, effective as of the payment date for
     such new dividend level. Accrued interest on the principal balance of the
     Loan shall be payable annually on the first business day of each April,
     commencing April 2001.

          4. MATURITY DATE. Subject to Section 6, the outstanding principal
     balance of the Loan, plus accrued but unpaid interest thereon, shall be due
     and payable on the first business day of April 2004.

          5. MANNER OF PAYMENT. The principal of, and interest on, the Loan
     shall be payable at Company's office at 14 Campus Boulevard, Suite 100,
     Newtown Square, Pennsylvania 19073 (or such other address as Company shall,
     from time to time, notify Executive). All such principal and interest shall
     be payable in lawful money of the United States of America in immediately
     available funds; provided, however, that Executive may, in his sole
     discretion, tender Common Shares to Company in repayment of all or any
     portion of the Loan and accrued interest thereon, with each share tendered
     valued at $15.625 (subject to equitable and proportionate adjustment in the
     event of a split or reverse split of, or share dividend on, the Common
     Shares).

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          6. LOAN FORGIVENESS.

               a. Upon a Change of Control of BRT, the outstanding principal
          balance of the Loan, plus accrued but unpaid interest thereon, shall
          automatically be forgiven. As used herein, the term "Change of
          Control" shall have the meaning assigned to it in the Amended and
          Restated Employment Agreement (the "Employment Agreement") between BRT
          and Executive.

               b. Within thirty (30) days following the first business day of
          each April 2001, 2002 and 2003, Company shall compute the total
          shareholder return on the Common Shares from February 18, 2000 through
          such first business day of April, and shall compare such total
          shareholder return to the total shareholder return over the same time
          period on the common shares of the other companies in the Peer Group
          (as defined below). If BRT's total shareholder return for each
          applicable period falls in the bottom quadrant of the Peer Group, then
          25% of one-third of the original principal amount of the Loan shall be
          automatically forgiven as of such computation date. If BRT's total
          shareholder return falls in the third, second or first quadrant of the
          Peer Group, then 50%, 75% or 100%, respectively, of one third of the
          original principal amount of the Loan shall be automatically forgiven
          as of the computation date.

               c. In addition to the forgiveness provided in the preceding
          paragraph, if BRT's total shareholder return for any of the three
          measurement periods specified in the preceding paragraph exceeds the
          average total shareholder return of the companies in the first
          quadrant of the Peer Group for any such measurement period, then any
          portion of the principal of the Loan that was previously eligible for
          forgiveness, but which was not forgiven, shall be automatically
          forgiven.

               d. Whenever a portion of the principal of the Loan is forgiven,
          accrued interest on such portion of the principal shall also be
          forgiven.

               e. The Peer Group shall initially consist of the following
          companies, in addition to BRT: Koger Equity Inc., SL Green Realty
          Corp., Kilroy Realty Corp., Prentiss Properties Trust, Reckson
          Associates Realty Corp., First Industry Realty Trust Inc., Arden
          Realty Inc., CarrAmerica Realty Corp., Highwoods Properties Inc.,
          Mack-Cali Realty Corp., Bedford Properties, Liberty Property Trust and
          Great Lakes. In the event that any of such companies is involved in a
          business combination or similar extraordinary transaction, it shall be
          removed from the Peer Group.

          7. TREATMENT OF LOAN. For purposes of the "three times multiplier"
     referenced in Sections 18(b) and (d) of the Employment Agreement, the
     amount of the Loan and any portion of the Loan that is forgiven shall not
     be treated as an amount paid to Executive pursuant to Section 5 of the
     Employment Agreement and shall not be treated as the short-term portion of
     any bonus amounts paid or payable to Executive pursuant to Section 6 of the
     Employment Agreement.

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          8. MISCELLANEOUS. This Agreement may be amended only by a written
     instrument executed by Company and Executive. This Agreement shall be
     governed by the laws of the State of Delaware.

     IN WITNESS WHEREOF, the parties have executed this Agreement as of the day
and year first above written.

                                     Brandywine Realty Trust

                                     By: ______________________________

                                     Title:____________________________

                                       _________________________________
                                             Anthony A. Nichols, Sr.

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