From December 1803 until the spring of 1804, Lewis and Clark prepared for their expedition here.
The Cahokia Courthouse State Historic Site is a reconstructed French-Canadian structure built about 1740 at what is now 107 Elm Street, Cahokia, Illinois. At various times it has served as a house and as a courthouse. It is currently interpreted to resemble its appearance about 1800 as a frontier courthouse of the Northwest Territory. The courthouse was listed on the National Register of Historic Places on November 9, 1972.