This feature class describes properties listed on the National Register of Historic Places, classified as historic structures, and depicted as polygons. The National Register of Historic Places requires the submission of a single UTM coordinate pair for properties under 10 acres or a series of bounding UTM coordinate pairs for properties over 10 acres. The polygons contained within this dataset represent boundaries created from connecting the bounding UTM coordinates submitted with the nomination. A structure is a building whose functional construction is made usually for purposes other than creating human shelter. Structures include: bridges, tunnels, gold dredges, firetowers, canals, turbines, dams, power plants, corncribs, silos, roadways, shot towers, windmills, grain elevators, kilns, mounds, cairns, palisade fortifications, earthworks, railroad grades, systems of roadways and paths, boats and ships, railroad locomotives and cars, telescopes, carousels, bandstands, gazebos and aircraft. Attribute data in this dataset are intentionally limited to those necessary for spatial data maintenance and feature level metadata necessary to document the lineage of the geography itself. Data from external database systems, such as the National Register Information System, are intended to link with these data to provide basic feature attributes. The means to maintain unique identifiers for each historic site (CR_ID), Survey_ID, as well as unique geometries associated with that feature (Geometry_ID) are through the use of Globally Unique Identifiers (GUIDs) assigned by the database. Information about the genesis of individual polygons is documented by feature level metadata fields in the spatial attribute table.