Castillo de San Marcos

The oldest extant Spanish fortification in the United States, this bulwark stands as a remnant of the European colonization of America. The Castillo de San Marcos dates back to 1672 and is a fine example of military architecture built in defense of the Spanish crown. The fort's masonry is called coquina and for more than 200 years of battle, this limestone withstood countless strikes among European powers. The dearth of traditional materials in Florida forced the Spanish to use this porous, yet resilient material, to the dismay of their enemies who found the fort impossible to conquer in battle. It was declared a national monument in 1924 and today, San Marcos remains a fascinating place. At the visitor's center one can join a ranger program, see a live re-enactment or just walk around and explore the fortress, whatever the choice, the fort definitely merits the trip.