Cahokia, also known as Cahokia Mounds State Historic Site,'s the site of an ancient Native American city (650–1400 CE) near Collinsville, Illinois in the American Bottom floodplain, across the Mississippi River from St. Louis, Missouri. The site included 120 man-made earthen mounds over an area of six square miles, although only 80 survive. Cahokia Mounds's the largest archaeological site related to the Mississippian culture, which developed advanced societies in eastern North America cen… (More on Cahokia)