Welcome to Castillo de San Marcos, the oldest masonry fort in the continental United States and a prime example of the “bastion system” of fortification. Built by the Spanish in the city of St. Augustine, Florida, its construction began in 1672, nearly 107 years after the city itself was founded by Pedro Menéndez de Avilés in 1565. St. Augustine is the oldest continuously inhabited European-established settlement within the borders of the contiguous United States.
The fort is a remarkable monument, not only because of its age but also due to its unique construction and historical significance. It’s made from coquina, a type of sedimentary rock that is composed almost entirely of ancient shells. This material is found locally and is quite resilient, absorbing or deflecting enemy shots rather than shattering.
Castillo de San Marcos was built to protect Spanish interests in the New World from foreign adversaries like the British and pirates. Its star-shaped design, with diamond-shaped bastions at each corner, allowed defenders to have overlapping fields of fire to protect against any approaching enemy.
Throughout its history, the fort has witnessed numerous conflicts and changed hands several times. It was seized by the British in 1763 as a result of the Treaty of Paris, which ended the Seven Years’ War. The British controlled it until 1783, when it was returned to Spain following the American Revolution and the subsequent Treaty of Paris. Finally, in 1821, the fort came under U.S. control after Florida was ceded to the United States by Spain.
During its American tenure, the fort has served multiple purposes, including military prison during the Seminole Wars and the Civil War. Notably, during the Indian Wars, Native American tribes such as the Seminole, including their leader Osceola, were imprisoned here.
The fort was renamed Fort Marion in 1821 in honor of Revolutionary War hero Francis Marion, but in 1942, its original name was restored by an Act of Congress to preserve its historical ties.
Today, Castillo de San Marcos is a National Monument managed by the U.S. National Park Service. As you walk through its grounds, you can explore the gun decks, the storerooms, and the soldier’s quarters, which have been well-preserved and provide a glimpse into the past lives of its inhabitants. The fort also offers stunning views of the Matanzas Bay, making it clear why this location was strategically chosen for defense.
Throughout the year, the fort hosts numerous historical reenactments, including cannon firings and soldier drills, allowing visitors to step back in time and experience the history that shaped this region.
