Fort Clinch is a 19th-century masonry coastal fortification, built as part of the Third System of seacoast defense conceived by the United States.

From 1736, various nations to control the territory have garrisoned and fortified this site to protect the entrance to the St. Marys River and Cumberland Sound.

It was part of its Third System of coastal defenses conceived earlier in the century, which guided fortifications throughout this period.

There are corner bastions and embrasures in the outer walls and several structures in the interior courtyards, including a two-story barracks.

However, changes in technology, specifically the development of rifled cannon, had improved weaponry to the point that the fort's brick walls were vulnerable to attacks and thus obsolete.

[3] State Park personnel reenact military life at the fort, which is open from 8:00am until sundown, year-round.