The moment
Around 1050 a Mississippian city grew rapidly on the floodplain east of today's St Louis, the largest settlement north of Mexico. Its people raised Monks Mound, the biggest earthen mound in North America, set up circles of cedar posts aligned to the solstices, and buried hundreds of people in Mound 72, many of them young women who had been sacrificed. The city declined after about 1200 and was abandoned within the next two centuries.