Centuries of Secrets at Cahokia Mounds - a UNESCO World Heritage Site in Southern Illinois

Monks Mound at Cahokia Mounds, a UNESCO World Heritage site in Illinois
Friday, March 24, 2017 - 8:12pm

Have you heard of Cahokia Mounds State Historic Site? If not, you're not alone. Despite its status as the most important archaeological site in North America, most people are not familiar with this lost city in Southern Illinois. 

It's suffered a myriad of indignities. For one, it's named for a tribe that arrived centuries after its original inhabitants disappeared. Another: its crowning achievement, a pyramid even greater than Giza's, was named for a group that lived nearby for less time than it takes to get a college degree.

A thousand years ago it was the epicenter of civilization, and now a four-lane highway cuts through the middle of it, a highway that is ironically part of why it's still around.

Cahokia Mounds State Historic Site is one of 23 UNESCO World Heritage Sites

Cahokia Mounds State Historic Site in Collinsville, Illinois, uniquely illustrates America's past, both pre-Columbian and post- “discovery.” The site, one of 23 UNESCO World Heritage Sites in the U.S., preserves the history of a city that existed long before Columbus stumbled onto that Bahamian beach. It tells the tale of those who built it and those who came after, from Trappist monks to a 19th century mechanic to the archaeologists who preserve their stories. It's continuing proof that civilization on this continent did not begin with the arrival of Europeans.

At first glance Cahokia may seem like just a bunch of dirt mounds, but it's much more than that. This planned city covered six square miles dotted with 120 earthworks, and seventy of them remain on the site's 2200 acres. The community began around 700AD, about the time the Chinese invented gunpowder, as a cluster of small settlements. Over the next couple of centuries those merged to become a larger community. By 1050 - 1150 the population had exploded to anywhere from 20,000 in most estimates to as high as 50,000 in others. To put this in perspective, London's population was around 20,000 and the Tower of London was constructed during this period. About a third of the inhabitants of Cahokia were immigrants, making this city North America's original melting pot.

By 1350 they were gone. Nobody knows where they went, or why they left.

Inside the interpretative center at Cahokia Mounds


The interpretive center inside the museum tells the story of the people who built these mounds


The mounds they built are the only reminder and remainder of their existence. Some were used for religious and ceremonial purposes. Others were for more “earthly” reasons. Mound 72 was a burial chamber filled with five mass graves of sacrificial victims, some beheaded and others buried alive, as well as more dignified burials for the nobility. Archaeologists found a copper workshop and a large Woodhenge, used to mark time and the changing of the seasons.

Because the inhabitants, like most peoples indigenous to the continent, had no written language, what is known of their culture is due to the investigations of archaeologists skilled in literally unearthing its mysteries. It's remarkable that they have as much with which to work as they do. When the French arrived in the early 1600s they found the Cahokia tribe in the area, hence the modern name of the site. These Illini plains Indians had no knowledge of the previous inhabitants, so they couldn't explain the mysteries. Similar mounds across the Mississippi River were razed and looted to become the city of St. Louis, and now only one significant mound remains in that area.


You can just see The Gateway Arch in St. Louis in the distance

In the early 1800s a group of French Trappist monks planted gardens on one of the terraces of the largest structure at Cahokia. This structure is now known as Monks Mound, even though the monks were only on-site from 1809 to 1813. To call it a mound seems to do it a disservice. The base of this beast covers over fourteen acres and the pyramid rises to a height of one hundred feet. It contains twenty-two million cubic feet of earth - larger in volume than the Great Pyramid of Egypt - every foot carried by hand in baskets. There are four terraces, and at the top of the highest sat a structure that was fifty feet tall.


View from the top of one of the terraces on Monks Mound


Stairs leading to the very top of Monks Mound

In 1831 a mechanic by the name of T. Amos Hill (coincidentally) bought the tract containing the mound and built a house at the top. When he built a well he pulled up not just dirt, but also human bones, pottery shards, and other evidence that the hill was man-made. As you can imagine, the water was not exactly palatable. A Mr. Flagg recounted in a journal in 1838, published as The Far West, that the odd taste was most likely due to the fact that "the precious fluid has probably filtrated, part of it at least, through the contents of a sepulcher."


Monks Mound at Cahokia Mounds


In 1864 the tract was purchased by Thomas J. Ramey. For nearly sixty years he and his family lived on the mound, but they also protected the area. As a member of the Illinois General Assembly Ramey pushed for its preservation. For years he and others, most notably archaeologist Warren K. Moorehead, tried to get the area designated a park, but it wasn't until a grassroots campaign in the early 1920s proved its significance that the state legislature passed a bill granting protected status. With 144.4 acres, Cahokia Mounds State Park was born.

One of the striking things about Cahokia is that U.S. 40, or Collinsville Road, runs right through it. Authorized in 1806 by Thomas Jefferson as the National Road, the section through Cahokia wasn't officially completed until the 1920s, but by that time wagons, trains, and streetcars had all cut through the complex and the route was well established.

Overlooking US 40 cutting through Cahokia Mounds

What helped to save Cahokia was the Federal Aid Highway Act of 1956. This legislation allowed for some of the money allocated for highway construction to be used in salvage operations for archaeologically significant sites that were in the path of progress. In 1960 Interstates 55 and 70 were about to go right through Cahokia. Activists took advantage of those funds and a series of "Woodhenges" were discovered, providing increased understanding of the historical significance of this Mississippian culture. 

In 1964 Cahokia Mounds was declared a National Historic Landmark, in 1966 it was added to the National Register of Historic Places, and in 1982 it became one of UNESCO's World Heritage Sites. Today this treasure trove of history opens the door to the past. With continued research, study, preservation, and appreciation, its forgotten secrets will be revealed for future generations to remember.

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Cahokia Mounds State Historic Site is a UNESCO World Heritage Site located in Illinois. #Cahokia #UNESCO #USA #historicsite
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Theresa Goodrich is the Emmy-winning founder and publisher of The Local Tourist. She's got a penchant for storytelling and a keen eye, and is the author of the book series.

30 Ramey St, Collinsville, IL 62234
Come visit the remains of the most sophisticated prehistoric native civilization north of Mexico at Cahokia Mounds State Historic and World Heritage Site.

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