Monks Mound

As a platform mound, the earthwork supported a wooden structure on the summit.

Located at the Cahokia Mounds UNESCO World Heritage Site near Collinsville, Illinois, the mound size was calculated in 1988 as about 100 feet (30 m) high

as finally completed around 1100 CE

the mound size was calculated in 1988 as about 100 feet (30 m) high

Monks Mound is the largest earthwork structure of the pre-Columbian Mississippian culture in North America, standing at the center of the Cahokia Mounds site near present day Collinsville, Illinois. Built in stages between roughly 900 and 1200 AD entirely from basket loads of earth carried and packed by hand, without draft animals or wheeled transport, the mound covers about 5 hectares at its base and rises in four terraces to a height of around 30 meters, the largest man-made earthen mound north of Mexico. Excavations suggest a large timber structure, likely the residence or ceremonial building of Cahokia's paramount ruler, once stood atop its highest terrace, overlooking a city that at its peak around 1100 AD may have held as many as 20,000 people. The mound takes its modern name from a small group of Trappist monks who briefly farmed one of its lower terraces in the early nineteenth century, and the wider Cahokia Mounds site was inscribed as a UNESCO World Heritage Site in 1982.

The structure rises in four terraces to a height of 100 feet (30 m) with a rectangular base covering nearly 15 acres (6.1 ha) and containing 22 million cubic feet of adobe, carried basket by basket to the site.