The Lost City of Cahokia

In last week's issue of the journal Science, Andrew Lawler gives a lengthy report on the forgotten city of Cahokia. For a while now archaeologists have known about this Native American settlement beneath modern East St. Louis, but many believed it was what Lawler calls a "seasonal encampment." A new round of archaeological digs, done in preparation for a bridge being constructed across the Mississippi River between Missouri and Illinois, has unearthed evidence of "a sophisticated, sprawling metropolis stretching across 13 kilometers on both sides of the Mississippi" that existed about a thousand years ago, Lawler writes:

Archaeologists believe people began to gather at Cahokia around the year 1000 A.D. Inspired perhaps by the sighting of Halley's Comet in the year 989, settlers erected ceremonial mounds at the site, some of which line up with the sun's position during the winter solstice. Around the year 1100 they began to build Monks Mound — the largest mound, reaching some 100 feet off the ground, created from millions of baskets of dirt. A vast palisade that enclosed Monks Mound and other parts of the settlement was constructed around the year 1200. For reasons still debated, the whole city failed around the start of the following century.