
Castillo de San Marcos National Monument
The Castillo is the city's defining landmark, a star-shaped fortress built by the Spanish between 1672 and 1695 from coquina, a soft stone made of compressed shells. Its walls famously absorbed cannonballs during sieges instead of cracking.
Allow one and a half to two hours. The grassy grounds around the fort are free to walk and lovely at sunset, and the fort is managed by the National Park Service, so check the official website for current hours and fees.
The fort's walls are built of coquina, a local shell stone that absorbed cannon fire rather than shattering. Photo: Jmelloni252, Wikimedia Commons, CC BY-SA 4.0
















