1
                                                                    Exhibit 3.91


                            CERTIFICATE OF AMENDMENT

                                       OF

                         CAPSTAR FORRESTAL COMPANY, L.L.C.


     1.   The name of the limited liability company is: CAPSTAR FORRESTAL
COMPANY, L.L.C.

     2.   The Certificate of Formation of the limited liability company is
hereby amended as follows:

          "2. The address of its registered office in the State of Delaware is
Corporation Trust Center, 1209 Orange Street, in the City of Wilmington, County
of New Castle. The name of its registered agent at such address is: The
Corporation Trust Company."

     3.   This Certificate of Amendment shall be effective on July 1, 1998.

     IN WITNESS WHEREOF, the undersigned has executed this Certificate of
Amendment of CAPSTAR FORRESTAL COMPANY, L.L.C. this 24th day of June, 1998.


                                   /s/ Christopher L. Bennett
                                       -------------------------
                                       Christopher L. Bennett
                                   By: Authorized Person

   2
                            CERTIFICATE OF FORMATION

                                       OF

                       CAPSTAR FORRESTAL COMPANY, L.L.C.


     This Certificate of Formation of CAPSTAR FORRESTAL COMPANY, L.L.C. (the
"LLC"), dated as of March 23, 1998, is being duly executed and filed by John E.
Plunket, as an authorized person, to form a limited liability company under the
Delaware Limited Liability Company Act (6 Del.C. Section 18-101, et. seq.)

     FIRST. The name of the limited liability company formed hereby is CapStar
Forrestal Company, L.L.C.

     SECOND. The address of the registered office of the LLC in the State of
Delaware is c/o United Corporate Services, Inc., 15 East North Street, Dover,
Delaware 19901.

     THIRD. The name and address of the registered agent for service of process
on the LLC in the State of Delaware is United Corporate Services, Inc., 15 East
North Street, Dover, Delaware 19901.

     IN WITNESS WHEREOF, the undersigned has executed this Certificate of
Formation as of the date first above written.



                                   /s/ John E. Plunket
                                       -------------------------
                                       John E. Plunket
                                       Authorized Person