Cahokia Mounds

Cahokia Mounds preserves the remains of the largest and most sophisticated ancient city north of Mexico — a Mississippian metropolis that flourished a thousand years ago on the Mississippi floodplain. At its height around 1100 CE it may have held more people than London, its skyline dominated by scores of enormous earthen mounds. The greatest of them, Monks Mound, is the largest earthwork in the Americas. Mysteriously abandoned before Europeans arrived, Cahokia is a monument to a vast, complex Native American civilization.

Beginning around 1050 CE, the Mississippian people built a great city on the fertile bottomlands east of the Mississippi River, in what is now southern Illinois. Known today as Cahokia — a name borrowed from a later, unrelated tribe, since the builders' own name for it is lost — it grew into the largest urban center in pre-Columbian North America, a hub of trade, religion, and political power.

At its peak around 1100 CE, Cahokia may have been home to 10,000 to 20,000 people or more, rivaling the great cities of Europe at the time. Its people raised more than a hundred earthen mounds as platforms for temples, elite residences, and ceremonies. The largest, Monks Mound, rose about 100 feet in four terraces, with a base broader than that of the Great Pyramid of Giza. A circle of tall wooden posts, nicknamed 'Woodhenge,' tracked the sun through the seasons.

For reasons still debated — among them climate change, flooding, resource exhaustion, and political upheaval — Cahokia declined through the 1200s and was abandoned by about 1350, generations before Europeans reached the region. Today around 80 of its mounds survive as Cahokia Mounds State Historic Site, a National Historic Landmark and, since 1982, a UNESCO World Heritage Site.