Archeologists date the first settlement at Cahokia to around 700, when Indian groups lived in villages along Cahokia Creek. Between 800-1000, the Mississippean culture developed, a highly structured society with a complex social and political system. Cahokia became a regional center surrounded by satellite towns and villages. By the year 1200, it sprawled over six square miles and had a population of between 10,000 and 20,000 people, making it the largest city north of Mexico.
Cahokia was organized around a huge mound (now known as Monks Mound) and a 40-acre plaza where public gatherings were held. Fields and farms surrounded the city and kept its residents supplied with food.
The mounds at Cahokia were made of earth dug with stone and wood tools and transported in baskets on people’s backs. A prodigious effort was involved in their construction: it is estimated that more than 50 million cubic feet of soil was used to construct the mounds. Most were rectangular in shape and were topped by ceremonial buildings and the residences of the elite members of the society. Other conical and ridgetop mounds were used as burial sites for important citizens. Mound 72, for example, included nearly 300 ceremonial burials, mostly of young women, as well as that of a male of about 45 years of age who was laid out on a platform of 20,000 marine shell beads formed into the shape of a raptor bird.
Monks Mound is the largest mound at Cahokia and contains an estimated 22 million cubic feet of earth. It is named after the French Trappist monks who lived on a nearby mound from 1809-1813 and who had fields and orchards on Monks Mound. The name “Cahokia” refers to the Cahokia tribe of the Illinois Confederacy, though they did not construct the mounds and arrived in the area several hundred years after the site had been abandoned by its original settlers.