Fort San Cristóbal (chris-TO-bahl), historic site, NE P.R., N Old San Juan, 1 mi/1.6 km ESE of El Morro Castle, facing the Atlantic Ocean. Fort built (16301771) to protect the city of San Juan from land attacks by the enemies of Spain. The first shot of the Spanish-American War was fired from this fort. Local hq. of the U.S. Department of the Interior and of the State Civil Defense located here.