El Morro, or formally known as El Castillo de San Felipe del Morro, rises 140 feet above the sea on a rocky promontory and is the oldest freestanding fort in the Americas. This impressive structure was built between 1539 and 1797 by Spanish settlers to defend the San Juan coastline during the 17th and 18th centuries. In 1983, it was declared a World Heritage Site by the United Nations.

The El Morro offers some of the most dramatic views in the Caribbean and affords visitors an intriguing labyrinth of dungeons, vaults, lookouts, barracks and ramps.