Cahokia lost city

Cahokia Mounds State Historic Site is the area of an ancient indigenous city (c. 600–1400 CE) located in the American Bottom floodplain, between East Saint Louis and Collinsville in south-western Illinois, across the Mississippi River from St. Louis, Missouri. The 2,200-acre (8.9 km2) site included 120 human-built earthwork mounds over an area of six square miles, of which 80 remain.Cahokia Mounds is the largest archaeological site related to the Mississippian culture, which developed advanced societies in central and eastern North America, beginning more than five centuries before the arrival of Europeans.
-Wikipedia-