45 C.F.R. § 3.41
The enclave is officially open to the public during normal working and visiting hours and for approved public events. The enclave is closed to the public at all other times, and the Director may also officially close all or part of the enclave, or any building, in emergency situations and at other times the Director deems necessary to ensure the orderly conduct of Government business. When all or part of the enclave is closed to the public, admission is restricted to employees and other authorized persons who may be required to display Government credentials or other identification when requested by a police officer and may be required to sign a register. The living quarters and adjacent areas are not open to the public but are open at all times to occupants and their visitors and business invitees, unless otherwise closed by the Director.
45 C.F.R. §3.41