Monks Mound

Monks Mound is an earthen platform in Madison County, Illinois, forming the center of the Cahokia archaeological site. The structure extends over a base covering roughly 5.7 hectares and rises about 30 meters (100 feet) above the surrounding land.

Builders from the Mississippi culture began construction in the 9th century and expanded the structure in several phases into the 13th century. The Cahokia settlement lost its population between 1250 and 1350 and was abandoned, with the reasons for decline still being researched.

The Mississippi culture inhabitants built this platform as the seat of political and religious authority within Cahokia society. The name comes from French monks who lived on the grounds in the 17th century, long after the original settlement declined.

Wooden stairs lead up to the upper plateau, offering a panoramic view over the river flats. The climb requires some fitness as the staircase includes many steps, but there are resting spots along the way.

The base area surpasses that of the Great Pyramid of Giza, making this construction the largest pre-Columbian earthwork in North America by footprint. Archaeologists estimate that the construction required around 15 million baskets of soil carried by hand.

Location: Madison County

Elevation above the sea: 157 m

Height: 30 m

Part of: Cahokia

GPS coordinates: 38.66070,-90.06200

Latest update: December 13, 2025 16:58