what is el morro

El Morro, also known as Castillo San Felipe del Morro, is a citadel located in Old San Juan, Puerto Rico. It was built between the 16th and 18th centuries and served as an important military outpost for Spain and later the United States. El Morro was constructed on a site chosen for its strategic location at the entrance to one of the best harbors in the Caribbean area. The fortification was transformed from its original medieval tower shape to a thick-walled masonry stronghold, capable of fully resisting the impact of cannon balls. El Morro was attacked several times by foreign powers, including the Dutch and the United States Navy during the Spanish-American War. In 1961, the US Army retired El Morro, passing it on to the National Park Service to establish a museum. Today, El Morro is a UNESCO World Heritage Site and a popular tourist attraction. Visitors can explore the fortification and its grounds, which include the oldest lighthouse on the island, built under Spanish rule in 1846.