The Castillo de San Marcos (Spanish for "St. Mark's Castle") is the oldest masonry fort in the continental United States; it is located on the western shore of Matanzas Bay in the city of St. Augustine, Florida. It was designed by the Spanish engineer Ignacio Daza, with construction beginning in 1672, 107 years after the city's founding by Spanish Admiral and conquistador Pedro Menéndez de Avilés, when Florida was part of the Spanish Empire. The fort's construction was ordered by Governor Francisco de la Guerra y de la Vega after a raid by the English privateer Robert Searles in 1668 that destroyed much of St. Augustine and damaged the existing wooden fort. Work proceeded under the administration of Guerra's successor, Manuel de Cendoya in 1671, and the first coquina stones were laid in 1672. The construction of the core of the current fortress was completed in 1695, although it would undergo many alterations and renovations over the centuries. Although built in part by black slaves owned by the Spanish, the fort later served as one of the first entry points of fugitive slaves from British North America into Spanish Florida, where they were freed by the colonial authorities. This quickly led to the first free Black settlement in the future United States (Fort Mose, formed just north of St Augustine). When Britain gained control of Florida in 1763 pursuant to the Treaty of Paris, St. Augustine became the capital of British East Florida, and the fort was renamed Fort St. Mark until the Peace of Paris (1783) when Florida was transferred back to Spain and the fort's original name restored. In 1819, Spain signed the Adams–Onís Treaty which ceded Florida to the United States in 1821; consequently, the fort was designated a United States Army base and renamed Fort Marion, in honor of American Revolutionary War hero Francis Marion. The fort was declared a National Monument in 1924, and after 251 years of continuous military possession, was deactivated in 1933. The site was subsequently turned over to the United States National Park Service. In 1942 the original name, Castillo de San Marcos, was restored by an Act of Congress. Castillo de San Marcos was attacked several times and twice besieged: first by English colonial forces led by Carolina Colony Governor James Moore in 1702, and then by English Georgia colonial Governor James Oglethorpe in 1740, but was never taken by