Castillo de San Marcos: history, tickets and visiting tips

Castillo de San Marcos is a Spanish stone fort on Matanzas Bay in St. Augustine, Florida, and the oldest masonry fort in the continental United States. Spain built it between 1672 and 1695 from coquina, a stone made of compressed shells. It was never taken by force, and the National Park Service now runs it as a national monument.

Plan your visit

Hours

Daily, first admission 9:00 am, last admission 5:00 pm; visitors leave by 5:15 pm. Closed Thanksgiving and Christmas Day.

Adults (16+)

$15, valid for 7 consecutive days

Children (15 and under)

Free, with an adult

Annual pass

$45 for this park; America the Beautiful passes are also accepted

Fee-free days

Several a year; the NPS lists them on its fees page

Run by

National Park Service: nps.gov/casa

Prices and hours are from the NPS website in November 2026.

When to go

• Quietest: mid-September to mid-November.
• Busiest: Christmas to New Year, school breaks and weekends. The NPS says a busy Saturday brings about 3,500 visitors.
• Storms: the gun deck closes during thunderstorms because of the lightning risk.
• Time: allow one to two hours, then walk into the old town across the street.

Why it was built

St. Augustine was founded by Pedro Menéndez de Avilés in 1565. In 1668 the English privateer Robert Searles raided the town, destroying much of it and damaging its wooden fort. Spain ordered a stone fort. It was designed by the engineer Ignacio Daza, and the first coquina was laid on October 2, 1672. Native Americans from Spain's nearby missions did most of the labor, with skilled workers brought from Havana. The core of the fort was finished in 1695.

Why coquina mattered

Coquina was quarried from the "King's Quarry" on Anastasia Island, across the bay, and ferried over. It is soft and porous, so cannonballs tended to sink into the walls rather than shatter them. With a star-shaped plan and four corner bastions (San Pedro, San Agustín, San Carlos and San Pablo), the fort was besieged twice, by Carolina's governor James Moore in 1702 and Georgia's James Oglethorpe in 1740, and never breached.

Who has held the fort

Every change of hands came by treaty or agreement. The fort became a national monument in 1924 and was deactivated in 1933, after 251 years of continuous military use.

For a wider Florida trip, our Florida days off the golf course pairs the Castillo with Molasses Reef in the Keys.