Castillo de San Marcos Facts

As one of the greatest fortifications in the world, Castillo de San Marcos is an engineering marvel. It was constructed to help protect St. Augustine from attack by sea and is unique among Spanish colonial forts in that it is completely enclosed by walls and has no vulnerable spot to land troops via ladders or catapults, making it nearly impenetrable.

Castillo de San Marcos was built by the Spanish to guard the entrance into St. Augustine, the oldest occupied city in North America and prized possession of Spain for 150 years.

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Castillo de San Marcos Facts for Kids

  • Castillo de San Marcos is America’s oldest masonry fort.
  • Built between 1672 and 1695, the Castillo de San Marcos is one of the oldest castles in the world.
  • The design was created by Ignacio Daza, a Spaniard, after a raid in 1668.
  • In 1763 the British took control and then renamed it Fort St. Mark.
  • As part of the Adams-Onis Treaty, it was ceded to the U.S. in 1821 and renamed Fort Marion.
  • Only in 1942 was the original name (Castillo de San Marcos ) of the fort returned by an act of Congress.
  • During Spain’s New World Empire, the Spanish built the fort to offer protection for the first European settlement in the U.S.
  • Castillo de San Marcos stonework is made from ancient shells that bond over time to create an exceptionally strong material.
  • Built as a six-sided structure, the fort has walls that stand 40 feet high and 12 feet thick.

The History of Castillo de San Marcos

As part of the colonial defenses, construction on Castillo de San Marcos began in 1672 and was completed by 1695. The redoubt was not complete when Spain lost Pensacola in 1719 to the British, which resulted in them adding a moat, ramparts, and two more bastions.

The garrison was replaced by the British, and the Spanish regained it in 1783. The United States took Florida from Spain in 1821, and they completed Fort Marion (as it was renamed) in 1848 on the site.

The fortifications were declared a National Monument in 1924 and began receiving restoration work in the 1930s by the Civilian Conservation Corps, which remained until 1942.

On April 10, 1948, United States Senator Claude Pepper called for the fortifications to be made a National Monument. President Harry S. Truman signed an Executive Order on April 10, 1948, that established Castillo de San Marcos as a National Monument, and it was federally protected by the National Park Service.

The fort is under the jurisdiction of St. Augustine National Park. It was listed on the National Register of Historic Places in 1971 and later on the Florida Historic Register in 1975.

In 2005, the fort was designated a U.S. National Historic Landmark.

Construction of the Fort

The foundation stone is made up out of coquina rock which consists of crushed coquina shells from nearby Anastasia Island. The walls are 20-feet high, 14-feet thick at the base, 6 feet thick at the top, and surrounded by a moat on three sides with water depths ranging from 10 to 18 feet deep.

The walls of the fort were painted red, white, and blue to signify the Spanish flags. The moat was covered with pine trees which would make it difficult for an enemy to get close enough to fire arrows at the fort.

The structure of the fort consisted of four bastions named San Pedro, San Agustín, San Carlos, and San Pablo with a ravelin called San Juan. The east side of the fort has three tiers with gates built into the first tier and also accessible from the carriageway or drawbridge.

The fort was built to withstand attacks from the sea and land.

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In 1875, the fort became a place of imprisonment for Native American prisoners of war. Many of the captives ultimately died at Fort Marion.

As soon as the United States gained control of the Castillo de San Marcos, General Francis Marion (the “Swamp Fox”) was renamed Fort Marion in his honor.

During the 1800s, Fort Marion was used to house several Seminole Native Americans and their followers, including and King Philip, as well as Chief Osceola. A few of the prisoners escaped and fought with the American soldiers, making the war last for another four years.

The fort separated from the United States during the American Civil War. In time, the Union forces were able to gain control over the fort.

The coquina stone for the walls came from Anastasia Island across the bay in 1672. The stone was brought back to St Augustine, where stonemasons constructed the blocks.

The British laid siege to St. Augustine and the Castillo de San Marcos in 1702. Throughout the two-month siege, 1200 Spaniards and 300 soldiers stayed within the fort. They ultimately claimed victory when the British were unable to take the fort.

The Castillo’s soft coquina walls absorbed cannon balls without damaging them.


How big is Castillo San Marcos

20.48 acres and is located at 11 South Castillo Drive St. Augustine, Florida

What is the St Augustine fort made of

The St. Augustine fort is made from coquina, a locally sourced stone-like compound made of shell and limestone.

What is special about Castillo de San Marcos

The Castillo is the oldest masonry fort in the continental United States: it has never been captured by an enemy force.

Why was Castillo de San Marcos built

Built by the Spanish to protect their interests in La Florida

The Castillo de San Marcos is located on the coast of St. Augustine, Florida, and it was built in 1672 to be used as a fortification against pirates.

It was also used to guard the entrance up to St. Augustine from one of the ports which were out of control before this fortification was created.

The Spanish had an interest in colonizing the area and took over many other towns in what is now known as Florida because they wanted to stop them from fitting with the French, British, and Dutch colonists that were nearby at that time.

This fortress encircled by water has been restored over time due to erosion but has continued to be used for ceremonial activities. The Castillo de San Marcos was established in order to prepare themselves for attacks by pirates who were a threat during the colonization of the area.

How is the Castillo de San Marcos still part of Florida’s history

The Castillo de San Marcos is one of the oldest forts in the continental United States. It’s a lasting piece of Florida’s history, and it plays an important role in telling the story of our state.

This fortress played a key role in battles.

It was also used as a military prison during World War II. The Castillo de San Marcos still stands today as both a tribute to those who came before and a symbol for what lies ahead: opportunity, growth, progress.

What does Castillo de San Marcos mean in English

Castillo de San Marco means Castle of Saint Mark.