A thousand years ago, huge pyramids and mounds of earth stood where East St. Louis now stretches in Southern Illinois. This majestic urban architecture towered over the swampy floodplains of the Mississippi River, blurring the small villages of the region. From the end of the 900s, word of the city spread throughout the Southeast. Thousands of people visited for celebrations and rituals, lured by the promise of a new kind of civilization. Many decided to stay.
At the top of the city in 1050, the population exploded to as many as 30,000 people. It was the largest pre-Columbian city in what later became the United States, larger than London or Paris at the time. The colorful wooden houses and monuments rose along the east side of the Mississippi, eventually spreading across the river to St. Louis. A particularly magnificent structure, known today as Monk’s Mound, marked the center of the downtown area. Towering 100 feet over a huge central plaza, it had three dramatically soaring levels, each topped with ceremonial buildings. Standing on the top level, a person speaking loudly could be heard across the Grand Plaza below. To the west, Monk’s Mound flanked a circle of tall wooden posts called Woodhenge that marked the solstices.
Despite its grandeur, the city’s name has been lost over time. The culture is known simply as Mississippian. When Europeans explored Illinois in the 17th century, the city had been abandoned for hundreds of years. At the time, the region was inhabited by the Cahokia, a tribe from the Illinois Confederation. Europeans decided to name the ancient city after them, despite the fact that the Cahokia themselves claimed no connection with it.
Centuries later, Cahokia’s meteoric rise and fall remains a mystery. It was booming in 1050, and by 1400 the population was gone, leaving a landscape completely geoengineered by human hands. Searching for clues to history, archaeologists dig through the thick, wet, tenacious clay Cahokians once used to build their mounds. Buried under just a few feet of earth are millennia-old building foundations, rubbish bins, the cryptic remains of public rituals, and in places even tombs.
To find out what happened to Cahokia, I participated in an archaeological dig there in July. It was led by two archaeologists who specialize in Cahokian history, Sarah Baires of Eastern Connecticut State University and Melissa Baltus of University of Toledo. They were assisted by Ph.D. candidate Elizabeth Watts of Indiana University, Bloomington, and a class of tireless students from the Institute for Field Research. Together they spent the summer opening three large trenches in what they thought would be a sleepy little residential area southwest of Monk’s Mound.
They were wrong. The more they dug, the clearer it became that this was no ordinary place. The structures they excavated were full of ritual objects charred by sacred fires. We found the remains of parties and a rare earth structure lined with yellow soil. Baires, Baltus and their team had accidentally stumbled upon an archaeological treasure trove connected to the city’s demise. The story of this place would take us back to the last decades of a great city whose social fabric underwent a radical transformation.
East St Louis palimpsest
Finding a lost city in the modern world isn’t exactly the same as playing Tomb Raider. Instead of slashing through the jungle and battling a dragon, I drove to Cahokia on a road that winds through the depressed neighborhoods of East St. Louis to Collinsville, Illinois. It was not until the 1970s that the elevated walkways and mounds of the old town were covered by suburban developments. Just west of Monk’s Mound was the Mounds Drive-In Theater. Farmers often plowed over Cahokia’s smaller monuments.
That all changed 40 years ago when Illinois declared Cahokia a Historic State and UNESCO granted it World Heritage status. The state purchased 2,200 acres of land from residents, clearing out the drive-in and a small subdivision. Now the Cahokia Mounds State Historic Site and Visitors’ Center is dedicated to preserving the remnants of the monumental architecture in the center of the old town.
When I got there last summer, archaeologists Baires, Baltus and their team had been digging for several weeks in the sweltering heat of southern Illinois. To reach their dig, I stopped on a gravel road behind some old gas tanks and trudged through the muddy grass of an unmarked field until I saw a bunch of people with shovels standing around three open pits. It was 7am but I was already a bit late – the team started around 6.30am each day to avoid the late afternoon heat.
Baires and Baltus chose to explore this humble area, known as the CABB Tract, based on a magnetometric survey Watts had done several months earlier. Using a handy shoulder-mounted magnetometer, Watts carefully walked all over the field, looking for signs of ancient habitation.
Magnetometers are perfect for locating buried structures because they can detect anomalies that represent disturbed soil, burned objects and metals several feet below the surface. Watts’ magnetometry map revealed a distinctive pattern of promising dark rectangular spots, whose shapes and positions were too precise to be natural. They looked very much like the floors of houses arranged in a semicircle, perhaps around a courtyard.
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An artist’s interpretation of what downtown Cahokia would have looked like in the late Sterling period, after the stockade wall was built around Monk’s Mound and the Grand Plaza.
National Geographic
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Artistic recreation of downtown Cahokia, with Monk’s Mound in the center.
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Monk Hill today.
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In the 1950s, Mounds Drive-In was at the base of Monk’s Mound. The state of Illinois repurchased the land as a conservation effort, and now Cahokia is a UNESCO World Heritage Site.
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Elizabeth Watts uses a chopstick to dig up delicate finds in Excavation Block 1. Sarah Baires watches their handiwork. You can see they just uncovered a rare earthenware trowel (it’s the round shape next to Baires’s knees), which was imported to Cahokia from the highlands.
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The triangular ceramic item you see is the handle of a cup that once contained Black Drink, a highly caffeinated beverage that Cahokians drank to induce hallucinations and vomiting during rituals. The archaeologist’s toe is included for size comparison.
The shape of the courtyard caught the attention of Baltus and Baires. Late in Cahokia’s history, there was an inexplicable shift in the town’s layout: people abruptly stopped building on a north-south grid and reverted to open courtyard plans that imitated village layouts before Cahokia’s founding . The archaeologists wanted to know what ordinary people did during the city’s transition, and this place was well outside the elite sphere of Monk’s Mound. They broke into the earth over three separate anomalies, eventually creating three trenches called excavation blocks (EB 1, 2, and 3 for short).
When I arrived, Baires, Baltus, and Watts looked down into EB1 and muttered to each other about what they’d found. “Ugh – what is this?” asked Baires, looking intently at the floor of a building that had not seen the light for nearly a thousand years. I knelt beside her at the carefully squared edge of the pit and tried to imagine a building here. “It’s a palimpsest,” Watts suggested. The group had uncovered layer after layer of material, suggesting that many structures have been built on the same site over time. Like most of the team, Watts stood barefoot in the muddy ditch around the ground where Cahokians once walked.
Even with my untrained eye I could see her pointing to overlapping building floors: an area of dark clay ended abruptly in a diagonal line like a wall, and next to it was a uniformly colored area of clay dotted with charcoal and artifacts. The walls themselves, made of piles sunk into the clay, had long since rotted away.
These buildings were not modest houses either. At least one ritual fire had burned here, the flames of which consumed valuable offerings, such as mica, a ceremonial cup for the highly caffeinated Black Drink, a beautifully woven mat, an earthenware trowel imported from a remote village, and an ancient projectile point from before the war. Cahokia peoples that would be centuries old by the time it was buried here. EB 2 and 3 were also unusual, yielding finds suggesting feasting and ritual earthmoving activity.
What Baires and Baltus thought would be a bunch of private homes turned out to be a public space full of “special use structures,” the preferred archaeological term for any building whose purpose goes beyond the mundane. People used these buildings for everything from political debates and social gatherings to spiritual practices and party venues. Baires looked over the neighborhood and said simply, “I’ve never seen anything like it.” I followed her gaze and could no longer see the field lined with trees and distant gas tanks. Instead, there were meeting halls, a wide courtyard with a decorated wooden pole in the center, and a sacred pit where Cahokians borrowed clay for their mounds. A huge rubbish dump full of deer bones and broken pottery indicated a great celebration.
I looked back in time to a time when the silent fields around me were filled with people, houses and hills to the horizon.