Which significant mound, located in Illinois, was built with soil specifically chosen for its strength?

Monks Mound is a significant earthwork located in the Cahokia Mounds complex in Illinois and is the largest pre-Columbian earthwork in the Americas. It was constructed by the Mississippian culture, and the choice of soil for this mound was intentional because the builders understood its strength and stability. This careful selection of material allowed Monks Mound to achieve impressive height and size, as well as durability over centuries.

The engineering techniques used in its construction reflect the advanced knowledge and skills of the Mississippian people regarding the properties of soil and the ability to create monumental structures. Monks Mound serves as a testament to the complexity of their society, including its agricultural development, social organization, and religious practices, making it a focal point of the Cahokia site.

The other mounds mentioned, while significant, do not possess the same level of notable engineering characteristics in relation to the specific choice of soil used for construction.