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Cahokia Mounds

Significant Archeological Attraction and a UNESCO World Heritage Site


Cahokia Mounds

Cahokia Mounds

Flickr user emilyrides

Ancient relic in the Cahokia Mounds Museum


Monks Mound, the largest man-made earthen mound in North America


Of all the UNESCO World Heritage Sites in the United States, the ancient mounds that make up the Cahokia Mounds State Historic Site are perhaps the least understood. Called America's Lost City by some, Cahokia had, at its height between 1100 and 1200 AD, a larger population than the city of London at the time. By the early 16th century, when the first Europeans began arriving in the New World, the mounds had been abandoned.

History and Location of the Mounds

Located in Collinsville, Illinois, just east of the city of St. Louis, Missouri, the Cahokia Mounds are the largest archeological site in North America north of central Mexico (aka, the largest archeological site in the United States and Canada). Archeologists date Cahokia to as far back as 700 AD, as they have discovered woodland tools and pottery from that time period. By 1000 AD, the Mississippian peoples were building mounds at this site for burial purposes and other rituals.

Shortly thereafter, at the turn of the 12th century, began the "Golden Age" of the Cahokia Mounds area. During this time, they built Woodhenges, large-scale calendars akin to Stonehenge but made with wooden posts; multiple mounds, including Monks Mound (Mound 38), the largest man-made earthen mound in North America; defensive palisade walls; and a 40-acre Grand Plaza.

For reasons largely unknown, the original inhabitants of this ancient city began to abandon it in the late 1300s. In the early 17th century, the Illinois Illiniwek, as well as its Cahokia sub-tribe, began to reclaim this land. As the Cahokia Indians were the last known Native Americans who settled in this territory, the Cahokia Mounds are named for them.

What to See When Visiting the Mounds

Urban development during the 19th and (beginning of the) 20th centuries led to the destruction of  many of the mounds. According to Hodges (see references below):

The relentless development of the 20th century took its own toll on Cahokia: Horseradish farmers razed its second biggest mound for fill in 1931, and the site has variously been home to a gambling hall, a housing subdivision, an airfield, and (adding insult to injury) a pornographic drive-in. But most of its central features survived, and nearly all of those survivors are now protected.

Cahokia Mounds is set on 2,200 acres and visitors to the site can explore approximately 800 acres. Guided tours of Cahokia, which are available at various times from April through October, typically include visits to:

  • Monks Mound: Also known as Mound 38. This 10-story mound consisting of four terraces is the largest man-made earthen mound in North America.
  • Mound 72: The mound where the "Birdman" was unearthed. The man, most likely a very prominent elder and/or chief, was buried atop beads that were in the shape of a falcon (this burial scene is re-created in the Interpretive Center). Mound 72 also contained skeletons of the bodies of approximately 250 men, women, and children, who were either killed in a ritual sacrifice and buried in the mound or buried alive in the mound.
  • Twin Mounds: Roughly proportional mounds. Photographers love these.
  • The Grand Plaza: A flat, grassy space of approximately 40 acres that served as ceremonial space during Cahokia's heyday.
  • Woodhenge: Also known as a sun calendar or a timber circle, Cahokia's Woodhenge is a 1985 reconstruction west of Monks Mound.
  • Interpretive Center: The site's museum contains artifacts unearthed from the mounds, information about the mounds' history and the culture of the Mississipian and Cahokian peoples.

Admission: Cahokia Mounds State Historic Park is free, but a donation is requested for upkeep of the archeological treasure.


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