From 3500 BCE to 1500 CE hundreds of huge earthen mounds were constructed in North America by native peoples. Discover the location of these mounds and view the fascinating archaeological remains of some of these mounds. Learn about the sociological and religious function of these mounds in civilizations such as the so-called Adena, Hopewell, Fort Indian, Woodland, Caddoan, and Mississippian Cultures, including the horrific human sacrifices which occurred during public spectacles atop the mounds. Marvel at the size of Cahokia, near present-day St. Louis, which in 1100 CE had a population of around 20,000—much greater than the cities of London or Paris at that time.