41 C.F.R. § 102-78.15 What are historic properties?
Title 41 - Public Contracts and Property Management
Historic properties are those that are included in, or eligible for inclusion in, the National Register of Historic Places (National Register) as more specifically defined at 36 CFR 800.16.
Title 41: Public Contracts and Property Management
PART 102–78—HISTORIC PRESERVATION
Subpart B—Historic Preservation
§ 102-78.15 What are historic properties?

