A representative landmark of Puerto Rico’s colonial legacy, the Castillo San Felipe del Morro, or El Morro for short, is an impressive citadel that sits at the very top of Old San Juan. Its construction began in 1539 and concluded around 1790; during those 250 years, the castle became a six-level fortress designed to protect the island from attackers approaching by sea. The bastion – integrated by barracks, dungeons, and storerooms – still holds some of the original cannons facing the ocean. This fortress has seen many battles over the centuries, from Sir Francis Drake’s attack in 1595 to the 1898 Bombardment of San Juan by the US Navy, but it has never been defeated. In 1898, as a result of the Spanish-American War, the island changed hands from Spain to the United States. The castle houses the oldest lighthouse on the island, built under Spanish rule in 1846. El Morro was later designated as part of Fort Brooke and actively used as a military installation during the First and Second World Wars. In 1961, the US Army retired El Morro, passing it on to the National Park Service to establish a museum.