San Juan National Historic Site

The San Juan National Historic Site protects the Spanish colonial fortifications anchoring the old city of San Juan, Puerto Rico — primarily Castillo San Felipe del Morro and Castillo San Cristóbal. Construction began in the 16th century as Spain sought to defend one of its most strategic Caribbean harbors against repeated attacks by the English, Dutch, and French. El Morro, the more visited of the two, was expanded continuously over two centuries before passing to the United States during the Spanish-American War in 1898, earning National Historic Site designation in 1949. Listed as a UNESCO World Heritage Site since 1983, the complex today invites visitors to walk through multi-level casemates, tunnel corridors, and sweeping green esplanades atop the fortification walls, with panoramic views across the Atlantic and into San Juan Bay.