Once the largest urban center north of Mexico, Cahokia Mounds State Historic Site in Collinsville, Illinois, stands as one of the most significant archaeological landscapes in North America. At its peak, ca. 950–1350, Cahokia was a thriving city of tens of thousands, defined by monumental earthworks, sophisticated planning, and far-reaching influence. Today it is a designated UNESCO World Heritage Site. Site interpreter Angela Cooper places Cahokia within the broader story of Indigenous North America, outlining its deep historical roots and the shared traditions of the Mississippian world.