The Cahokia Mounds State Historic Site (11 MS 2) is the site of a pre-Columbian Native American city (which existed 1050–1350 CE) directly across the Mississippi River from modern St. Louis, Missouri. This historic park lies in south-western Illinois between East St. Louis and Collinsville. The park covers , or about , and contains about 80 mounds, but the ancient city was much larger. At its apex around 1100 CE, the city covered about and included about 120 manmade earthen mounds in a wide range of sizes, shapes, and functions. At the apex of its population, Cahokia may have briefly exceeded contemporaneous London, which at that time was approximately 14,000–18,000.