41 C.F.R. § 101-8.311
(a) Definitions. For purposes of this section:
(b) Obligation—(1) Accessibility. A recipient shall operate any program or activity involving Historic Preservation Programs so that when each part is viewed in its entirety it is readily accessible to and usable by handicapped persons.
This paragraph does not necessarily require a recipient to make each of its existing historic properties or every part of an historic property accessible to and usable by handicapped persons. Methods of achieving accessibility include:
(iv) Adopting other innovative methods to achieve accessibility.
Because the primary benefit of an Historic Preservation Program is the experience of the historic property itself, in taking steps to achieve accessibility, recipients shall give priority to those means which make the historic property, or portions thereof, physically accessible to handicapped individuals.
(2) Waiver of accessibility standards. Where accessibility cannot be achieved without causing a substantial impairment of significant historic features, the Administrator may grant a waiver of the accessibility requirement. In determining whether accessibility can be achieved without causing a substantial impairment, the Administrator shall consider the following factors:
(iv) Cost of alterations in comparison to the increase in accessibility.
The Administrator shall periodically review any waiver granted under this section and may withdraw it if technological advances or other changes so warrant.
[47 FR 25337, June 11, 1982, as amended at 68 FR 51374, Aug. 26, 2003]