Cahokia Mounds Monks Mound sideview - stock photo

Side view of Monks Mounds terraces, Cahokia Mounds State Historic Site, Illinois -- the new world's largest pre-historic structure, 900 A.D. The remains of the most sophisticated prehistoric native civilization north of Mexico are preserved at Cahokia Mounds State Historic Site. Within the 2,200-acre tract, located a few miles west of Collinsville, Illinois, lie the archaeological remnants of the central section of the ancient settlement that is today known as Cahokia. The largest mound at the Cahokia site, the largest man-made earthen mound in the North American continent, is Monks Mound (Mound 38). It received its name from the group of Trappist Monks who lived on one of the nearby mounds. The Monks never lived on the biggest mound but gardened its first terrace and nearby areas.