Cahokia Mounds State Historic Site

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Ancient Mississippians

Centuries before the French founded Saint Louis in 1764, the ancient Mississippians created a major settlement on what is now the Illinois side of the Mississippi River. Cahokia was located in a strategic position near the confluence of the Mississippi, Missouri, and Illinois rivers. The Mississippians traded with communities as far away as the Great Lakes to the north and the Gulf Coast to the south.

Native Americans began building the city and its mounds around 700 AD. The city grew to cover 4,000 acres, with a population of around twenty thousand at its peak in 1100 AD. It was the largest city north of the pre-Columbian cities in Mexico.

The city was designed around the North-South and East-West axis points, with the 10-story Monks Mound in the center. The mounds made use of 55 million cubic feet of dirt. All was excavated by hand and carried in woven baskets to the construction sites. Some of the mounds were burial mounds. Others served as ceremonial centers.

Today, the park covers 2200 acres and contains 80 manmade mounds. It is also one of the 24 UNESCO World Heritage Sites within the United States. The visitor center and museum was closed for renovation when I visited, but I was able to explore Monks Mound.

Monks Mound

Monks Mound covers 14 acres and rises 100 ft. It was topped by a massive 5,000 sq ft, 5-story building. A huge platform mound with four terraces, Monks Mound was the largest structure and central focus of the city. It saw as many as 10 different expansions. The building is thought to have been a temple or the chief’s residence.

I climbed the steps to the top of Monks Mound in spite of the stifling heat that day. From the top, I could see other smaller mounds and the Gateway Arch off in the distance. There are several interpretive signs along the paths.

St. Louis Posts


Location: Collinsville, IL
Designation: National Historic Landmark, UNESCO site
Date designated/established: July 19, 1964
Date of my visit: July 16, 2022