Built to defend Florida and the Atlantic trade route, Castillo de San Marcos National Monument preserves the oldest masonry fortification in the continental United States and interprets more than 450 years of cultural intersections.
The fort 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.
Over the next years, different governors struggled against changing plans, financial setbacks, epidemics, storms, starvation, attacks, and lack of royal support. It was not until August of 1695 that the Castillo was declared finished, under the supervision of Laureano de Torres y Ayala, though it would undergo many alterations and renovations over the centuries.
The fort was declared a National Monument in 1924, and after 251 years of continuous military possession, was deactivated in 1933. Ownership of the Castillo was transferred to the National Park Service in the same year, and it has been a popular tourist destination since then.