Fort San Cristóbal stands on a hill at the e. edge of Old San Juan n. of Ave. Muñoz Rivera at San Juan National Historic Site. The 27-acre (11-hectare) fortification was the largest ever built by the Spanish in the New World. Constructed 1635-1783, the castle fort is connected to outworks by a series of tunnels and dry moats. Gunrooms, barracks and officers' quarters surround the main courtyard. The fort's powerful artillery repelled British forces attacking from the east in 1797. The first shot of the Spanish-American War in Puerto Rico was fired from the fort in 1898.
Guided tours of the national historic site are available by reservation. Comfortable walking shoes are recommended.