Capt Jean Baptiste Saucier, the builder of Fort de Chartres, shortly after 1737 built this log-and-stone structure for his residence. It is a unique monument to the early French settlers of the Illinois country and an excellent example of French colonial architecture. The oldest house in Illinois, possibly the earliest surviving dwelling in the Midwest, and without doubt the oldest courthouse west of the Allegheny Mountains, it has been completely reconstructed.

The construction is of special interest because of the vertical placement of the wall logs; the interstices contain stone and mortar. The building measures about 35 by 43 feet-unusually large-and consists of four rooms and a large attic. The builder's son sold it to the United States in 1793, after which it served as a US courthouse and a center of political activity in the old Northwest. After the county seat was moved from Cahokia in 1814, it was used as a saloon, storehouse, public hall, and finally as a home again.

In 1904, the building was exhibited at the Louisiana Purchase Exposition in St. Louis, and was then purchased by the Chicago Historical Society. Part of it was exhibited in Jackson Park, Chicago, until 1938, when Illinois State archeologists excavated the original foundation site and discovered a number of objects relating to the building. In 1939, as part of a WPA program, the building was reerected on the original site, and much of the original material employed. The State of Illinois maintains the Cahokia Courthouse as a State memorial. - NPS