Located on Illinois Route 155, four miles west of Prairie du Rocher, the site marks the location of the last of three successive forts named “de Chartres” built by the French during their eighteenth-century colonial occupation of what is today Illinois. The first two forts were erected in the 1720s and were square palisaded wooden structures with corner bastions. The 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. The fort gate, built in the 1920s, has been remodeled several times. Portions of the fort's walls were reconstructed on original foundations in 1989. The site was declared a National Historic Landmark in 1960 and was added to the National Register of Historic Places in 1976.

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 eighteenth-century Illinois.

Interpretive signs at various locations guide visitors around the site, and every weekend at least one costumed interpreter offers information on the history of the three forts. The museum is open daily. A trading post, housed in a structure resembling the fort’s reproduced stone buildings, offers souvenirs, snack foods, and reproductions of items that might have been found in eighteenth-century Illinois. Recreational facilities outside the reproduced fort include a day-use area with a picnic shelter and horseshoe pits.

The site hosts a number of special events, including the “Fort de Chartres Rendezvous” held in June, the “French and Indian War Winter Encampment” in February, “Kids Days” in May, the “French and Indian War Assemblage” in September, “French Colonial Crafts and Trades” in October, and “La Guianne” in December. Contact the site for details.