SCOTT SIMON, HOST:
This is WEEKEND EDITION from NPR News. I'm Scott Simon. Across the Mississippi River from St. Louis' famous Gateway Arch is part of Illinois that's a post-industrial wasteland. Some hope the construction of a new bridge across the river will help revitalize the area but archaeologists worry that future development could destroy what's left of a different neighborhood - one that flourished there almost 1,000 years ago. St. Louis Public Radio's Veronique Lacapra reports.
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VERONIQUE LACAPRA, BYLINE: If it sounds more like a construction site than an archaeological dig, that's because it is one. Crews are building a stretch of interstate freeway here leading to a new bridge that will span the Mississippi River from Illinois into St. Louis. But there are archaeologists here too, working just ahead of the cranes and earth movers.
They've unearthed the remains of a sophisticated American Indian settlement no one knew existed. There's the remnants of more than 1,000 prehistoric houses and the base of an earthen pyramid, one of dozens that would've towered above the original settlement.
JOE GALLOY: One of the things that I imagine an ancient visitor to this site would have experienced was kind of a sense of awe and wonder.
LACAPRA: Joe Galloy is coordinating research here for the Illinois State Archaeological Survey. Today, this East St. Louis dig sits halfway between a crumbling meat packing plant and a now-closed strip club. But Galloy says 900 years ago, visitors paddling here by canoe from the Mississippi River would have seen the tall wooden temples that stood on top of many of the pyramids. And at their bases, rows and rows of thatched-roof huts.
GALLOY: There would be, you know, fires and things like that. People cooking stuff - all sorts of activity. And you'd see this huge village. And it was probably a very impressive site, one of the largest settlements that people had seen if they hadn't been around this area before.
LACAPRA: Galloy says archaeologists knew about the pyramids from old maps and excavations, but they were all outside the bounds of this new dig site.
GALLOY: So for us it was a really big surprise to come out and discover that we have this big residential area for this ancient city.
LACAPRA: Galloy and others believe that what they've found here near East St. Louis is a prehistoric suburb of an ancient city known as Cahokia It was once the largest American Indian city north of Mexico. Its remains are five miles away from here. What's left of Cahokia is now part of an Illinois State Park. It's also a UNESCO World Heritage Site.
Cahokia is considered the greatest achievement of Mississippian culture, which once spread throughout the Central and Southern U.S. Here, there were 120 massive pyramids of earth - more than twice the number of any other site. Now, those pyramids are eroded, grassy mounds.
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LACAPRA: I've come to climb the tallest one with site manager Bill Iseminger. Monks Mound, as it's called, is 10 stories high, with a base that would cover about a dozen football fields. And Iseminger says it was all built by hand.
BILL ISEMINGER: The mounds were built a basket-load at a time. They didn't have horses or wagons or carts - all done with human labor.
LACAPRA: Nine hundred year ago, most of these mounds, or pyramids, would have supported wood and thatch buildings. From the towering temple on the top of this mound, we would have looked out over more pyramids, more temples, elite homes, meeting halls and charnel houses, where the dead were prepared for burial.
And spreading out below us, a vast ceremonial plaza, bustling neighborhoods, and in the distance, the rich floodplain of the Mississippi River, where the Cahokians caught deer and fish and harvested corn, squash and other crops. Archaeologists estimate that as many as 20,000 American Indians lived here. And now, with the discovery of the East St. Louis site, they think there may have been thousands more. But Iseminger says exactly what attracted so many people here is still a mystery.
ISEMINGER: Was there a powerful leader here, or charismatic leader, that drew people in, attracted people? Did something happen here that drew them in? Or something about the location was more significant? Those kinds of things we just don't have answers for directly, you know.
LACAPRA: Some scientists think Cahokia was a powerful spiritual center, like Jerusalem or Mecca. University of Illinois anthropologist Tim Pauketat, who has studied Cahokia since the mid-1980s, says it once attracted thousands of visitors, possibly religious pilgrims.
TIM PAUKETAT: We can look around the Eastern United States and just see a huge area in which we can identify Cahokian objects, suggesting that people from Wisconsin, Louisiana, over to Georgia even, Oklahoma, at least, occasionally came in and then went home with something from here.
LACAPRA: Until the surprise discovery of the new settlement, archaeologists thought this was pretty much all that was left of Cahokia - that almost everything else had been destroyed by development.
And Tim Pauketat is worried. By the time the East St. Louis dig wraps up later this year, only about a tenth of the ancient settlement will have been excavated. And Pauketat says once the new Mississippi River bridge is finished, the other 90 percent, which is still buried under private land, could be destroyed.
PAUKETAT: Because East St. Louis, you know, is right across from St. Louis. It's prime land for any kind of commercial development.
LACAPRA: Pauketat and a number of other archaeologists are trying to get the federal government to buy the land around the dig site. They want to see the new Cahokian settlement combined with the larger state-run site and protected as a national park. But Pauketat admits that so far, that doesn't seem likely. For NPR News, I'm Veronique Lacapra. Transcript provided by NPR, Copyright National Public Radio.