<PAGE>   1
                                                                 EXHIBIT 10.66



                    AMENDMENT TO REVOLVING CREDIT AGREEMENT
                            AND OTHER LOAN DOCUMENTS


     This Amendment to Revolving Credit Agreement and Other Loan Documents
("Amendment") is made as of this 27th day of June, 1997, by and between
AMBASSADOR APARTMENTS, L.P., a Delaware limited partnership, having an office
address at 77 West Wacker Drive, Suite 4040, Chicago, Illinois 60601
("Borrower"), and CREDIT LYONNAIS NEW YORK BRANCH, a branch, licensed under the
laws of the state of New York, of a banking corporation organized under the
laws of the Republic of France, having an office at Credit Lyonnais Building,
1301 Avenue of Americas, New York, New York 10019 ("Lender") and its successors
and assigns.


                             PRELIMINARY STATEMENT

     A. Borrower is a limited partnership whose sole general partner is
Ambassador Apartments, Inc., a Maryland corporation (the "REIT").

     B. The REIT is listed on the New York Stock Exchange and qualifies as a
real estate investment trust.

     C. Borrower and Lender are parties to a certain Revolving Credit Agreement
dated May 28, 1997 (the "Credit Agreement").  By the terms of the Credit
Agreement, Lender has agreed to extend to Borrower a revolving loan (the
"Loan") in the maximum amount of $25,000,000.  All terms used herein shall have
the meaning set forth in the Credit Agreement.

     D. As of May 30, 1997, Borrower was in default under the Bank One Credit
Agreement (the "Violation") which is an Event of Default pursuant to Section
11.1(o) of the Credit Agreement (the "Default").

     E. By the certain Letter Agreement dated May 30, 1997 (the "Side Letter"),
executed by Borrower, Borrower agreed that no more than $3,125,000 of Working
Capital Advances and no Acquisition Advances shall be outstanding until the
Bank One Credit Agreement is amended to eliminate the Violation.

     F. Borrower has arranged for a replacement line of credit with Nomura
Asset Capital Corporation ("Nomura"), to repay all indebtedness outstanding
under the Bank One Credit Agreement, thereby eliminating the Violation.

     G. Borrower has requested that Lender waive the Default pursuant to
Section 11.1(o), and to once again make disbursements of the Loan, and Lender
has agreed to do so subject to the terms contained herein.

     E. Borrower and Lender desire to amend the Credit Agreement, and the Note,
as provided herein.

<PAGE>   2


     THEREFORE, in consideration of the foregoing and for other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:


                                   AGREEMENTS

     1. Incorporation of Preliminary Statement and all Exhibits:  The foregoing
Preliminary Statement is hereby incorporated as if fully set forth herein.

     2. Defined Terms:  The terms used in this Amendment shall have the same
definitions as set forth in the Credit Agreement, to the extent that such terms
are not redefined in this Amendment.

     3. Credit Agreement:  Borrower and Lender hereby amend the Credit
Agreement as follows:

          (a) Term of Loan.  Section 4.4 of the Credit Agreement is hereby
     amended to read as follows:

          Without limiting the provisions of the Note, the unpaid principal
     balance of each advance made hereunder shall be due and payable on or
     before 90 days following the date of such advance, and the full amount of
     the unpaid principal balance of the Loan, together with any accrued and
     unpaid interest and all other sums then due and payable under the Note and
     under the other Loan Documents, if not sooner paid, whether by reason of
     acceleration or otherwise, shall be paid in full on December 31, 1997 (the
     "Maturity Date").  Lender shall have no obligation to make a disbursement
     of the Loan on or after the Maturity Date.

          (b) Events of Default.  Section 11.1(o) of the Credit Agreement is
     hereby amended to read as follows:

          If a default occurs under that certain Credit Agreement (the "Nomura
     Credit Agreement") dated as of June 22, 1997, among Ambassador II, L.P., a
     Delaware limited partnership and Nomura Asset Capital Corporation (as
     amended) and continues beyond the applicable grace period, if any,
     contained therein, or if a default occurs under any other revolving line
     of credit facility for which Borrower or the REIT is the borrower or a
     guarantor, and such default continues beyond the applicable cure period,
     if any.

     4. Waiver.  To the extent that there is or was any default, Default or
Event of Default under the Credit Agreement or any of the other Loan Documents
solely arising out of or on account of the existence, terms or status of the
Bank One Credit Agreement or any of the documents or instruments further
evidencing or securing the loan governed by the Bank One 

                                     -2-

<PAGE>   3

Credit Agreement, the Lender hereby waives such default, Default and Event of
Default ab initio. Lender further agrees that (a) it is not entitled to
exercise any rights or remedies under the Credit Agreement or any of the other
Loan Documents on account of such default, Default or Event of Default; and (b)
no such default, Default, Event of Default now exists or previously existed
under the Credit Agreement or any of the other Loan Documents because of
the waiver set forth in the immediately preceding sentence.

     5. Note: Borrower and Lender hereby amend the Note as follows:

          (a) The definition "Maturity Date" in the Note is amended to be
     December 31, 1997.

     6. Status of Side Letter.  Borrower represents and warrants to Lender that
all indebtedness outstanding under the Bank One Credit Agreement has been
repaid and the Bank One Credit Agreement has been terminated.  Based on such
representation, Lender agrees that such termination and the execution and
delivery of the Nomura Credit Agreement satisfy the requirements of the Side
Letter and that Acquisition Advances are available in accordance with the terms
contained in the Credit Agreement.

     7. Payment of Costs.  Borrower agrees to pay all reasonable fees and
expenses of the Lender incurred as of the date hereof in connection with the
Amendment as contemplated herein, including Lender's reasonable legal fees and
expenses.

     8. Representations and Warranties:  Borrower represents and warrants to
Lender as follows: (a) all representations and warranties contained in the
Credit Agreement are each true and correct in all material respects on the date
hereof and are made as of the date hereof; (b) there exists no default or event
of default under the Credit Agreement or any other Loan Document (other than
the Violation which will be waived pursuant to Paragraph 4 above); (c) the
Borrower has no defenses or offsets to the enforcement of the Loan Documents.

     9. Amendment Controlling:  In the event of a conflict or inconsistency
between the provisions of the original Loan Documents and the provisions of
this Amendment the provisions of this Amendment shall govern.  All of the Loan
Documents, as hereby amended are ratified and confirmed hereby by Borrower.

     10. Successor and Assigns:  Subject to the limitations set forth in the
Credit Agreement, this Amendment shall be binding upon, and shall inure to the
benefit of, the parties hereto and their respective successors and assigns.

     11. Counterparts:  This Amendment may be executed in two or more
counterparts, each of which may be executed by one or more of the parties
hereto, but all of which, when taken together, shall constitute but one
Agreement.

                                     -3-


<PAGE>   4

     12. WAIVER OF JURY TRIAL:  LENDER AND BORROWER, BY THEIR EXECUTION HEREOF,
EACH HEREBY WAIVE ANY RIGHT TO A TRIAL BY JURY IN ANY ACTION OR PROCEEDING TO
ENFORCE OR DEFEND ANY RIGHT HEREOF UNDER THIS AGREEMENT OR ANY OTHER LOAN
DOCUMENTS RELATING THERETO OR ARISING FROM THE LENDING RELATIONSHIP WHICH IS
THE SUBJECT OF THIS AMENDMENT AND AGREE THAT ANY SUCH ACTION OR PROCEEDING
SHALL BE TRIED BEFORE A COURT AND NOT BEFORE A JURY.

     13. Integration:  This Amendment together with the Loan Documents and the
Waiver executed by Borrower and Lender on June 26, 1997, constitute the entire
Agreement between Lender and the Borrower, and all other affiliated parties
with respect to the Loan and to the subject matter of the foregoing documents,
and all prior writings and discussions and all contemporaneous discussion are
hereby merged into and superseded by the provisions of the foregoing documents.

                [SIGNATURES ARE CONTAINED ON THE FOLLOWING PAGE]

                                     -4-


<PAGE>   5


     IN WITNESS WHEREOF, Borrower and Lender have caused this Amendment to be
executed as an instrument under seal as of the date hereof.


                                     BORROWER:

                                     AMBASSADOR APARTMENTS, L.P., A 
                                     DELAWARE LIMITED PARTNERSHIP


                                     BY:  AMBASSADOR APARTMENTS, INC., a 
                                          Maryland corporation

                                     By:
                                        ------------------------------
                                     Its:
                                        ------------------------------


                                     LENDER:

 
                                     CREDIT LYONNAIS NEW YORK BRANCH, A BRANCH,
                                     LICENSED UNDER THE LAWS OF THE STATE OF NEW
                                     YORK, OF A BANKING CORPORATION ORGANIZED 
                                     UNDER THE LAWS OF THE REPUBLIC OF FRANCE

                                          By:
                                             ------------------------------
                                          Its:
                                             ------------------------------


                                     -5-