Castillo de San Marcos
The Spanish fort Castillo de San Marcos is a "must not miss" St. Augustine attraction. The National Park Service maintains the Fort on 20.5 acres and keeps it open every day except Christmas. Built of native coquina rock, the Castillo de San Marcos is the oldest masonry and only extant 17th-century fort in North America.
The fort is an excellent example of the "bastion system" of fortification. It was never taken by force, only by treaty. Six different flags have flown over Castillo de San Marcos, including the Spanish flag and the U.S. flag twice.
After Pirates ransacked St. Augustine, construction began on the Castillo in 1672. The Castillo de San Marcos' rich history thus embodies the struggle and contest of the entire colonial era as well as the foundations of early America. Historic weapons demonstrations including canon firings occur most Fridays, Saturdays, and Sundays.