Monks Mound is the largest earthen structure in North America, located in Cahokia Mounds State Historic Site near Collinsville, Illinois. It stands about 100 feet tall and covers approximately 14 acres. Built by the Cahokia civilization around 1000 AD, it served as a ceremonial and political center. The mound is part of a larger complex of mounds and structures that once supported a thriving urban center. Archaeological studies suggest that it was likely topped with a wooden structure, possibly a temple or residence for leaders. Today, it is a UNESCO World Heritage Site, attracting visitors interested in ancient cultures.