What and Where Is the Castillo de San Marcos?

Castillo de San Marcos was built between 1672 and 1695.
Castillo de San Marcos was built between 1672 and 1695.

The Castillo de San Marcos is a National Monument in the United States, located in the city of St. Augustine, Florida, on the western side of Matanzas Bay. It is a fort built of stone and is considered the oldest masonry fort in the continental United States. Construction of the Castillo de San Marcos began in 1672 and was completed in 1695. The monument site occupies a land area of 20.5 acres. The fort was built with fire-resistant material. Initially, construction began during the period of Spanish occupation, during which Florida was part of the Spanish Empire. The structure’s core was completed in 1695, after many alterations and reconstructions. Today, the Castillo de San Marcos is a popular historical site in the United States and receives thousands of visitors every year.

Structure of the Castillo de San Marcos

The fort is built as a masonry star fort, with coquina, also known as shell stone. The walls are approximately 10 meters high (33 feet) and about 4 meters thick. The fort was unique in that it was built from stone, unlike the previous forts on the same site that were built from wood. There were ten previous fortresses built before the Castillo de San Marcos. The fort was vital during the struggle between Spanish and British forces for the control of the southeastern United States.

When the British won and acquired Florida, the fort’s name was changed from the Castillo de San Marcos to Fort Marion. The name change was done in honor of American Revolutionary War hero General Francis Marion. The fort was subsequently used as a military prison. Many Native Americans were held in Fort Marion as prisoners during the Seminole War (1835-1842). During the American Civil War, the fort was used by Confederate soldiers. In 1900, the fort was decommissioned.

Significant Battles and Sieges

During the countless colonial wars by European powers, the Castillo de San Marcos weathered most of these wars and remained strong despite numerous attacks. The main sieges which the fort withstood include the 1702 Siege of St. Augustine and the 1740 Siege of St. Augustine, both of which were initiated by British forces. The first attack on the Castillo de San Marcos occurred in November 1702, just a week after the fort's completion. This attack was carried out by James Moore, who used fire to attack the city of St. Augustine and the fort. The 1740 siege proved to be the most ferocious attack, as British forces took control of the city for a month, yet the fort successfully protected the Spanish control from within its walls.

Cultural Significance of the Site and Monument

The Castillo de San Marcos is a vital site in American history as it records the influences of numerous cultures. Various groups are associated with the site including Native Americans, Spanish, English, and African Americans.


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