Cahokia platform-mound city

Timeline

1. 1141–1144Monks Mound and central plaza · IllinoisBetween 1141 and 1144, Cahokia had already passed its population peak of 1050–1100 CE; construction of large platforms had largely ceased, but Monks Mound (about 30 meters high) and the central plaza still formed the ceremonial and administrative core. Archaeology shows some peripheral residential areas beginning to be abandoned, with the population dispersing to smaller surrounding settlements.
2. 1145–1148Woodhenge · CahokiaDuring this period, astronomical-ceremonial facilities such as the woodhenge may still have been used for winter solstice and equinox observations and sacrificial activities, reflecting the Mississippian culture's continuing concern with cosmic order. The spatial sequence of platforms, plazas, and woodhenge reflects the elite's monopolistic interpretation of time and space in a hierarchical society.
3. 1149–1150Mississippi River basin · Mississippian regionBetween 1149 and 1150, Cahokia's core population continued to decline, and the platform-mound city shifted from an active metropolis to a regional ceremonial site. Despite local decline, its architectural patterns, social hierarchy, and exchange networks had profoundly influenced the wider Mississippian region over the preceding centuries, leaving the most important archaeological testimony of North American prehistoric urbanization.