Cahokia Mounds State Historic Site

Cahokia Mounds State Historic Site is the remnants of a major Mississippian-period urban centre located near present-day Collinsville, Illinois, on the east bank of the Mississippi River opposite the St. Louis region. The site preserves large earthworks, plazas and settlement remains from a pre-Columbian complex city.

The monumental core includes an immense multi-level platform mound, numerous smaller platform and burial mounds, timber-circle constructions used for celestial observation and broad plaza spaces that organized civic and ceremonial activities. Archaeological evidence shows planned urban design and large-scale labour mobilisation.

Cahokia developed and flourished during the Mississippian period, with its peak occupation generally dated to about 1050 to 1350 CE; estimates suggest the urban population reached into the thousands, making it one of the largest settlements north of Mexico in that era. Over subsequent centuries the site was abandoned and later preserved as an archaeological park.

The site lies in southwestern Illinois near the city of Collinsville and is part of the greater St. Louis metropolitan area, occupying flat riverine land adjacent to the Mississippi River and accessible by regional roads from nearby urban centres.

• Monks Mound dimensions and viewing: the largest earthen pyramid north of Mesoamerica has a base covering roughly 14 acres and rises to a height of around 30 metres, and an observation platform provides views over the central plaza and surrounding mounds.

What to See#

• Monks Mound: North America’s largest pre-Columbian earthen structure, an enormous multi-tiered platform mound built and altered over centuries to form ceremonial and elite space at the heart of the ancient city.
• Outlying mounds, Woodhenge and plazas: A series of smaller burial and platform mounds, timber circle remains known as Woodhenge used for calendrical observation, and plaza areas that structured civic and ceremonial life across the site.
• Mound 72 (burial mound): A mortuary mound containing rich burial deposits and grave goods that reflect social differentiation and elite ritual practice within the Mississippian cultural system.

Cahokia Mounds State Historic Site sits on the Illinois side of the Mississippi River near Collinsville, about 10 miles (≈16 km) east/northeast of downtown St. Louis. By car from St. Louis expect roughly 20-30 minutes depending on traffic; cross the river into Illinois and follow local roads/signs to Collinsville/Cahokia Mounds where the site has on‑site parking and a visitor centre.

• Arrive early on a weekday-mornings are quieter and cooler, which makes it easier to experience the site's major earthworks before tour groups appear.
• Begin your visit at the Cahokia Mounds Interpretive Center to get orientation, exhibits and maps that explain the site layout and walking routes.
• Make time to walk beyond Monk's Mound: visitors often miss the reconstructed Woodhenge and the network of smaller mounds and trails surrounding the central plaza.