Historic buildings are a resource created principally to shelter any form of human activity, such as a house. These resources would include features such as: farmhouses, homesites, mansions, churches, museums (if the building is historic), courthouses, offices, prisons, train depots, etc. Historic buildings most often function primarily as dwellings. The point may represent the center of the building, an entrance, a corner, etc., while the polygon may represent the building footprint. Structures are a functional construction made for purposes other than creating shelter, such as a bridge. These resources would include features such as: fortifications, earthworks, roads, fences, canals, dams, engineering features, barns, outbuildings, arsenals, ships, manufacturing facilities, etc. These resources represent sites that do not function primarily as dwellings, however they may serve temporarily to house humans, although their primarily purpose is not a permanent shelter. The point may represent the location of a culvert, while a line may represent a fence or road, and a polygon may represent the circumscribed boundary of a manufacturing plant.