The site marks the location of the last of three successive forts named "de Chartres" built by the French during their 18th-century colonial occupation of what is today Illinois. This third fort, erected in the 1750s, was a massive square stone structure enclosing six buildings, including a still-standing powder magazine that may be the oldest building in Illinois. This fort served as the French seat of government and its chief military installation in the Illinois Country. In 1763 France ceded much of its territory in North America, including Illinois, to Great Britain. British troops occupied the fort from 1765 until 1772, when encroachment by the Mississippi River caused a collapse of the south wall. Subsequently, the remaining walls and buildings fell into ruin. The site features an imaginative reconstruction of portions of the third Fort de Chartres. Inside the fort are the restored powder magazine (portions of which are original), several reconstructed stone buildings, and the exposed foundations of other buildings, which have been "ghosted" in wood. The powder magazine is stocked with reproduction barrels and barrel racks. A combination museum and office building, built in 1928 on the foundation of an original fort building, houses exhibits depicting French life at Fort de Chartres. The large stone "Guards' House," built in 1936, contains a Catholic chapel furnished in the style of the 1750s, along with a priest's room, a gunner's room, an officer-of-the-day room, and a guard's room. Also on the grounds are an operating bake oven, a garden shed built of upright logs in "post-on-sill" construction, and a kitchen garden with raised beds of produce that would have been grown in 18th-century Illinois.
The site offers exhibits, tours, and educational and recreational events.