EXHIBIT 2.11


                                  AMENDMENT TO
                              AMENDED AND RESTATED

                        AGREEMENT OF LIMITED PARTNERSHIP

                                       OF

                       BLUE BELL INVESTMENT COMPANY, L.P.

               This Amendment to the Amended and Restated Agreement of Limited
Partnership dated October 14, 1997 (the "Partnership Agreement") of Blue Bell
Investment Company, L.P. (the "Partnership") is intended to be effective as of
October 14, 1997 (the "Effective Date"), and is by and among Corporate Office
Properties Holdings, Inc. (formerly known as FCO Holdings, Inc.), as general
partner (the "General Partner"), and Corporate Office Properties, L.P. (formerly
known as FCO, L.P.) ("COPLP") and Shidler Equities, L.P. ("Shidler"), as limited
partners.

                                    RECITALS

               The General Partner, COPT and Shidler (individually, a "Partner"
and collectively, the "Partners") constitute all of the Partners of the
Partnership and are the parties to the Partnership Agreement. The Partners
desire to amend the Partnership Agreement as set forth below. All capitalized
terms not otherwise defined in this Agreement shall have the same meaning as in
the Partnership Agreement.

               NOW, THEREFORE, in consideration of mutual promises and
agreements contained herein, and intending to be legally bound, the Partners
hereby agree that, effective as of the Effective Date, the Partnership Agreement
be amended as follows:

               1. SPECIAL ALLOCATION ON SALE OF ASSETS. Notwithstanding anything
in the Partnership Agreement to the contrary, in the event of the sale, transfer
or other disposition of all or substantially all of the assets of the
Partnership, if Shidler shall have a deficit balance in his Capital Account,
after taking into account all items of income or gain required to be allocated
to Shidler under Section 5.2(c) of the Partnership Agreement (but before taking
into account the allocation of other items of Profit or gain of the Partnership
for the Fiscal Year such sale or other disposition occurs), then all remaining
items of Profit and gain shall be allocated 

                                      -2-


exclusively to Shidler, to the extent necessary to eliminate any deficit balance
in Shidler's Capital Account. If any item of Profit or gain is specially
allocated to Shidler under the preceding sentence, then all subsequent
allocations to the Partners shall, to the extent possible without causing
Shidler to have a deficit balance in his Capital Account, be made so that the
balance in each Partner's Capital Account will be the same as if there were no
special allocation of Profit or gain to Shidler under the preceding sentence.

               2. LIMITED OBLIGATION TO RESTORE DEFICIT CAPITAL ACCOUNT.
Notwithstanding anything in the Partnership Agreement to the contrary, if
Shidler has a deficit balance in his Capital Account following the liquidation
of the Partnership, or following the liquidation of his interest in the
Partnership, after taking into account all Capital Account adjustments for the
Fiscal Year during which such liquidation occurs, Shidler shall be
unconditionally obligated to restore the amount of such deficit balance to the
Partnership by the end of such Fiscal Year or, if later, within 90 days after
the date of such liquidation; provided, however, that such obligation to
contribute additional amounts to the Partnership shall in no event exceed the
LESSER of (i) Shidler's proportionate share, based on his Percentage Interest,
of the Partnership's recourse debt and partner nonrecourse debt (as defined in
Treasury Regulation ss.1.704-2(b)(4)) or (ii) the amount set forth on Exhibit A
attached hereto, as the same may be amended from time to time with Shidler's
written consent. All amounts contributed by Shidler pursuant to this Section 2
shall be used to pay Partnership creditors or be distributed to Partners in
accordance with their positive Capital Accounts.

               3. GOVERNING LAW. This Amendment shall be governed by the laws of
the State of Delaware.

               4. COUNTERPARTS. This Amendment may be executed by facsimile
signatures and in any number of counterparts, all of which, when taken together,
shall constitute one and the same instrument.

               5. OTHER PROVISIONS IN FULL FORCE AND EFFECT. Except as modified
herein, all other terms and provisions of the Partnership Agreement shall remain
in full force and effect.

               6. BINDING EFFECT. This Agreement shall be binding upon all
successors and assigns of the Partners.

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               IN WITNESS WHEREOF, the undersigned Partners have executed this
Amendment as of the day and date first above written.

                                GENERAL PARTNER:

                                CORPORATE OFFICE PROPERTIES HOLDINGS, INC.

                                By:   /s/ Clay W. Hamlin, III
                                   ------------------------------------

                                LIMITED PARTNERS:

                                CORPORATE OFFICE PROPERTIES, L.P.

                                By:  Corporate Office Properties
                                     Trust, a Maryland business trust,
                                     its general partner

                                By:   /s/ Clay W. Hamlin, III
                                   ------------------------------------

                                /s/ Jay H. Shidler
                                ---------------------------------------
                                 Jay H. Shidler



                                    EXHIBIT A

Maximum Amount Shidler Equities, L.P. is required
to contribute to the Partnership pursuant to
Paragraph 2 of this Amendment .................................$1,200,000.00
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