The Lost City of Cahokia stretching 13km.......... East St. Louis
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:
Back then, hundreds of well-thatched rectangular houses, carefully aligned along the cardinal directions, stood here, overshadowed by dozens of enormous earthen mounds flanked by large ceremonial plazas.
Cahokia proper was the only pre-Columbian city north of the Rio Grande, and it was large even by European and Mesoamerican standards of the day, drawing immigrants from hundreds of kilometers around to live, work, and participate in mass ceremonies.
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.
The latest excavations have uncovered evidence of more than five hundred thatched houses and signs of workshops where residents created various goods. The homes surrounded the ceremonial sites, and at its peak the settlement may have expanded out into a primitive metropolitan area that served as residence to tens of thousands of Native Americans. But as a city Cahokia lacked the density of Mayan or European settlements; instead it appears to have organized itself more along the lines of "modern American urban sprawl," Lawler writes.
http://www.theatlanticcities.com/arts-and-lifestyle/2012/01/lost-city-cahokia/848/