force. However, possession of the fort has changed five times, all peaceful, among four different governments: Spain, 1695–1763 and 1783–1821, Kingdom of Great Britain, 1763–1783, and the United States of America, 1821–date (during 1861–1865, under control of the Confederate States of America). Under United States control the fort was used as a military prison to incarcerate members of Native American tribes starting with the Seminole—including the famous war chief, Osceola, in the Second Seminole War—and members of western tribes, including Geronimo's band of Chiricahua Apache. The Native American art form known as Ledger Art had its origins at the fort during the imprisonment of members of the Plains tribes such as Howling Wolf of the southern Cheyenne. Ownership of the Castillo was transferred to the National Park Service in 1933, and it has been a popular tourist destination ever since. Structure The European city of St. Augustine was founded by the admiral Pedro Menéndez de Avilés for the Spanish Crown in 1565 on the site of a former Native American village called Seloy. The need for fortifications was recognized after it was attacked by Sir Francis Drake and his fleet of 22 ships in 1586, and over the next 80 years, a succession of nine wooden forts were built in various locations along the coastline. After an attack in 1668 by the English pirate Robert Searle, however, during which the town of St. Augustine was burned to the ground, wooden forts were deemed inadequate, and Mariana, Queen Regent of Spain, approved the construction of a masonry fortification to protect the city. The Castillo is a masonry star fort made of a stone called coquina (Spanish for "small shells"), which consists of ancient shells that have bonded together to form a sedimentary rock similar to limestone. Native Americans from Spain's nearby missions did most of the labor, with additional skilled workers brought in from Havana, Cuba. The coquina was quarried from the 'King's Quarry' on Anastasia Island in what is today Anastasia State Park across Matanzas Bay from the Castillo, and ferried across to the construction site. Construction began on and lasted twenty-three years, with completion in 1695. The fort has four bastions named San Pedro, San Agustín, San Carlos, and San Pablo, with a ravelin protecting the sally port. On the two landward sides, a large glacis was constructed which would force any attackers to advance upward toward the fort's