Castillo de San Marcos
Oldest masonry fort in the continental U.S. Originally constructed by the Spanish between 1672 - 1695 with major modifications from 1738 - 1756. Later, the British, Spanish and Americans all made changes to the Castillo before it was finally retired as an active fortification in 1900. Proclaimed a national monument in 1924, the Castillo is now a prominent tourist destination where people of all cultures step back in time and reflect on the forces and events which have shaped world history.