Cahokia Mounds State Historic Site
The Cahokia Mounds State Historic Site is the site of a pre-Columbian Native American city (c. 600–1400 CE) directly across the Mississippi River from modern St. Louis. The park covers 2,200 acres, or about 3.5 square miles, and contains about 80 mounds. The ancient city was much larger. The Cahokia Museum and Interpretive Center receives up to a million visitors a year.