El Morro and San Cristobal are both part of the San Juan National Historic Site, a part of the U.S. National Parks Service. The rest of the site includes bastions, powder houses, and most of the wall that surrounds the city of Old San Juan. The other fort at the western end of the entrance to San Juan Bay is called San Juan de la Cruz, on the Isla de Cabras. This intense defense system kept Spain's power intact in the New World, for centuries. The significance of Puerto Rico's pivotal role regarding the wealth of the Caribbean sometimes gets lost in the "Pirates of the Caribbean" fantasy.
