The first two forts were erected in the 1720s and were square palisaded wooden structures with corner bastions.
The third fort, erected in 1753, was a massive square stone structure enclosing six buildings, including a still-standing powder magazine that may be the oldest building in Illinois.
|The third fort, erected in 1753|
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.
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.
photographs copyright © Neil Gale, Ph.D.
 Post-on-Sill - In line with customary French architecture, the unknown builder built the cabin with logs raised vertically. This was different from having the logs placed horizontally, as had become the custom among English-speaking frontiersmen farther east. The French colonial building style is called poteaux-sur-solle in French (English Translation: post on sill) construction, with the building's posts grounded in a foundation sill to retard wood rot.