National Register of Historic Places
The National Register of Historic Places (NRHP) is the United States federal government's official list of sites, buildings, structures, districts, and objects deemed worthy of preservation for their historical significance or "great artistic value". The enactment of the National Historic Preservation Act (NHPA) in 1966 established the National Register and the process for adding properties to it.
Source: Wikipedia — National Register of Historic Places (CC BY-SA 4.0)