Structures are defined by the National Register of Historic Places as "functional constructions made usually for purposes other than creating shelter." Common kinds of historic structures in Georgia include water towers, wells, and windmills, agricultural "outbuildings" such as corncribs or silos, and fortifications, bridges, icehouses, power plants, railroads, and roads. Other familiar structures include lighthouses, tunnels, dams, and bandstands. Less numerous historic "structures" include railroad locomotives and other rolling stock as well as ships, boats, and other watercraft.
Another kind of historic structure, less commonly recognized, is the structured environment: the large-scale, two-dimensional plans or patterns that underlie historic development. Historic structured environments include city plans, courthouse squares, agricultural field patterns, land-lot lines, suburban subdivisions, and the layout of parks, gardens, cemeteries, and yards.