SoHo, the Manhattan neighborhood SOuth of HOuston St, has the world's largest collection of cast-iron facades. This construction technique not only reduced cost but allowed for ornate features to be prefabricated in foundries from molds and used as building facades. The historic district is officially bounded by Houston Street, West Broadway, Canal Street and Crosby Street. It is noted for the elaborate cast-iron architecture of many of its buildings, most of which date from the late 19th century. These buildings originally housed warehouses, factories and sweatshops. It is also noted for its cobblestone streets, which were eventually repaved with the exception of Crosby Street, Wooster Street, Mercer Street and part of Howard Street.