San Juan National Historic Site includes forts San Cristóbal, San Felipe del Morro, and San Juan de la Cruz also called El Cañuelo, plus bastions, powder houses, and three fourths of the city wall. All these defensive fortifications surround the old, colonial portion of San Juan, Puerto Rico. El Cañuelo Fort is located at Isla de Cabras at the western end of the entrance to the San Juan Bay. These magnificent historic forts were built by Spanish troops beginning in 1539 with a tower at El Morro and La Fortaleza and took more that 250 years. Most of the walls we see today were added later in a period of tremendous construction from the 1760's -1780's.