Castillo de San Marcos (St. Mark's Castle), St. Augustine (must see)

Situated at the mouth of the Matanzas River in St. Augustine is a national monument known as St. Mark's Castle (Castillo de San Marcos). Dating from the late 17th century, it is the continental United State's oldest masonry fort.

Construction of this massive stone fortress began after attacks on a series of coastal wooden forts failed to offer adequate protection for the city. Castillo de San Marcos was built from coquina, a sedimentary rock formed from tiny sea shells. Once this fortification was completed, no siege or cannon fire could bring it down!

When the British took control of Florida in 1763, they renamed the fortress Fort St. Mark. In the 1820s, after the United States gained ownership of Florida, the name was changed again — now known as Fort Marion after Revolutionary War patriot and hero General Francis Marion. By 1900, the fort was deactivated and later transferred to the National Park Service.

A self-guided tour around Castillo de San Marcos offers plenty to see. This strong fortification boasts walls that are 14 feet thick. Pathways are there to guide you on a walk around this massive, well-preserved structure and its dry moat. Climb the stairs to the gun deck for a picturesque view of the St. Augustine skyline and the nearby bay.

Inside the fortress are various rooms to explore, including guard rooms, a chapel, storage areas, a treasury room, and a jail. There are also early latrines, museum exhibits, and an interior courtyard. Entry to the inside is accessed via a drawbridge that leads to a "sally port" (a secure gateway or entrance/exit into a fortification).

The fort was declared a National Monument in 1924, and its original Spanish name, Castillo de San Marcos, was restored by Congress in 1942. One bit of trivia is that Florida's first golf course opened on the grounds of Castillo de San Marcos (at the time known as "Fort Marion") in the 1890s. An exploration of this landmark is a must-do on your St. Augustine tour.