Castillo de San Marcos National Monument Tours Ticket Facility

America Begins Here Built by the Spanish in St. Augustine to defend Florida and the Atlantic trade route, Castillo de San Marcos National Monument preserves the oldest masonry fortification in the continental United States. Explore over 300 years of Florida history as you make your way through this fortress built in the late 1600s. From its commanding position on the waters of Matanzas Bay, a garrison of Spanish troops safeguarded St. Augustine during the turbulent colonial era. Later English and then American troops also saw service here. Museums highlighting various chapters of the fort’s long history occupy the bombproof storerooms that surround the central Plaza de Armas.