The so-called "moonlight (or moon) towers" in Austin are the only surviving examples of the tower lighting systems that were common in American cities in the late 1800s. The towers, erected in 1894 and 1895, were fabricated by the Fort Wayne Electric Company and shipped in pieces to Austin. They are 165 feet tall, of vertical truss assembly, and braced by guy wires. The original installation contract included electric generators installed at Austin dam on the Colorado River. During their early years, the towers were equipped with carbon-arc lamps, which diffused light over a large area. In 1925 the towers were converted to incandescent lamps and in 1936 to mercury-vapor lamps. Of the original thirty-one erected, in the early 1990s seventeen still stood, most of them in old residential neighborhoods near downtown. In 1970 the towers were designated official state archeological landmarks, and by 1976 they had been added to the National Register of Historic Places. During the early 1990s the city of Austin undertook a comprehensive restoration program, taking each of the towers down and sandblasting, repairing, and repainting it, then replacing it on its original site.