Cahokia Mounds State Historic Site

Cahokia Mounds is the largest pre-Columbian settlement north of Mexico, occupying roughly 5 square miles of the Mississippi River floodplain in southwestern Illinois. Flourishing from c. 950 to 1350 CE as the center of Mississippian culture, the city reached a peak population of up to 20,000. Its principal structure, Monks Mound, is the largest prehistoric earthen construction in the Western Hemisphere, rising 100 feet and covering over 14 acres. The site features approximately 70 preserved mounds and was designated a UNESCO World Heritage Site in 1982.