Castillo de San Marcos
The Castillo de San Marcos is the oldest masonry fort in the continental U.S., located on the western shore of Matanzas Bay in the city of St. Augustine, Florida. The fort was ordered to be built by Governor Francisco de la Guerra y de la Vega after the raid by the English privateer, Robert Searles, in 1668. The first stone was not laid until 1672. The fort's possession has peacefully changed six times among four different governments: the Spanish Empire, the Kingdom of Great Britain, the Confederate States of America, and the United States of America (Spain and the United States possessed the fort each two times).