Old San Juan (Spanish: Viejo San Juan) is the oldest settlement within Puerto Rico and the historic colonial section of the city of San Juan. The settlement is a National Historic Landmark District and was listed on the National Register of Historic Places as the “Zona Histórica de San Juan” (San Juan Historic Site). Old San Juan is located on a small and narrow island which lies along the north coast, about 35 miles (56 km) from the east end of Puerto Rico, and is united to the mainland of Puerto Rico by three bridges. It is bounded by the Atlantic Ocean to the north and to the south by San Juan Bay (or “Bahía de San Juan”) — which lies between the city and the mainland. On a bluff about 100 feet (30 m) high at the west end of the island and commanding the entrance to the harbor, rise the battlements of Fort San Felipe del Morro, in which there is a lighthouse.