When British forces laid siege to the Spanish settlement at St. Augustine in 1702, locals hid inside the coquina walls of the Castillo de San Marcos. Three decades later, the Brits tried — and failed — again.
Construction of the Castillo began a hundred years before the American Revolution. Through the centuries, the Castillo saw Spanish, British, American and Confederate flags fly over its ramparts, but the fort never fell to enemy forces.
Today, it is a National Monument, at the heart of the historic district in America’s Oldest City.
Location
St. Augustine, Florida
Why it matters
Nine wooden forts were built on the site, dating back to 1565, to protect Spanish interests in the area. Construction of the Castillo began in 1672 and took nearly a quarter-century to complete. Its walls, 12 to 19 feet thick, are made of coquina, a rock made up of millions of tiny clam shells quarried nearby. Coquina proved to be a good choice, since cannonballs bounced off its surface.
The British took over and renamed it Fort St. Mark in 1763. The U.S. government changed the name again in 1824, to Fort Marion, and used it as a prison for Native Americans. The facility was proclaimed a national monument in 1924 and transferred to the National Park Service in 1933. The Castillo name was restored in 1942.
What to see today
The Castillo is across the street from St. Augustine’s popular tourist district, so no tour of the city is complete without at least walking around the fortress. The long, sloping hill leading up to the fort is a popular place for picnics, kite-flying and kids rolling themselves dizzy. Inside, visitors tour displays telling the Castillo’s history and plug their ears when re-enactors blast cannons from the elevated ramparts.
Ask a local
You’re not likely to spend all day at the Castillo, but you could easily spend a day in St. Augustine’s Historic District. Stroll the bayfront, walk across the historic Bridge of Lions, try one of the dozens of bars and restaurants or shop for some funky gifts along pedestrian-only St. George Street.
Plan your visit
This article originally appeared on Florida Times-Union: The Florida fortress that withstood centuries of attacks
Reporting by Tom Szaroleta, Jacksonville Florida Times-Union / Florida Times-Union
USA TODAY Network via Reuters Connect



