The Castillo de San Marcos is a masonry star fort constructed of stone called coquina, Spanish for "small shells", by the Spanish Empire to protect its colony of St. Augustine. Workers were brought in from Havana, Cuba, to construct the fort in addition to Native American laborers. 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 October 2, 1672 and lasted twenty-three years, with completion in 1695. Since being transferred to the Park Service in 1933, the Castillo has become a popular tourist attraction. It occupies 2.5 acres in downtown St. Augustine, Florida.