The ancient site known for its elaborate burial mounds and artifacts is Cahokia, located near present-day Collinsville, Illinois. Cahokia was a pre-Columbian Native American city and served as a major cultural center for the Mississippian culture. It features large earthen mounds, the most famous being Monks Mound, which is one of the largest prehistoric earthen structures in the Americas. The site also includes various artifacts such as pottery, tools, and ceremonial items, indicating a complex society with social stratification and trade networks. Cahokia’s significance lies in its size, sophistication, and the insights it provides into ancient North American civilizations.