The fortress above the lagoon was built in 1733 to protect Spanish colonists from pirate attacks and rebellions by local indigenous people. It also served as an important outpost for the Spanish in the War of the Castes. In 1859 it was seized by Maya rebels, who held the fort until Quintana Roo was conquered by Mexican troops in 1901.
Today, with formidable cannons still on its ramparts, the fortress remains an imposing sight. It houses a museum exhibiting colonial armaments and uniforms from the 17th and 18th centuries.