Monk's Mound is the largest pre-columbian earthwork of its type in North America. Located in what is now Collinsville, IL, it is over 100 feet tall, 1000 feet long, and 800 feet wide. It is comprised primarily of four layers, or terraces, each smaller than the last and probably added later. It is the only mound with more than two terraces in the eastern half of North America.

It was constructed by the a branch of the Mississippian civilization of the Mound Builder people, whose city is now known as Cahokia, where it was probably used as a monumental structure for religious or governmental ceremonies. It may have been topped by a building as much as 50 feet tall. Its function may have been akin to the pyramids of mesoamerican civilizations, with ceremonies and/or government functions carried out on its various levels.

It acquired its modern name generations after the building civilization fell, though, when a group of Christian monks lived nearby, possibly gardening on its first terrace.

Over the years, the mound has eroded, or been damaged by man, significantly, so that the original size is now uncertain.