The Ancient civilizations of the Maya, Aztec and Inca flourished in Central and South America in the centuries before European colonists came to the region in the 15th and 16th Centuries. But further North, in what is now the United States, there were also large indigenous settlements. Cahokia, in the present state of Illinois, was the largest. At its peak, sometime around the 12th Century, Cahokia was home to nearly 20,000 people.
Just a short drive east of Saint Louis, and across the Mississippi into Illinois, is America's first city. All that remains after centuries of desertion are the earthen hills that give Cahokia Mounds its name. Archaeologist Bill Isemenger says the mounds are the remains of temples and homes, purposefully built by the early culture scientists call "Mississippians."
"To elevate your leaders and your important people and your religious beliefs higher than anybody else," said Isemenger. "Perhaps separate the sacred from the common to some degree."
Monk's Mound stands nearly 30 meters high, and it's thought Mississippian priests believed the elevation brought them closer to God. Now, joggers use it for an entirely different purpose.
Isemenger says the people here had traditional roles. Men probably hunted, and women probably raised children. But he says everyone probably shoveled dirt.
"Part of that role was to help build mounds," he said. "We don't think it was slaves."
Researchers know a lot about these people, but like many indigenous cultures, no one really knows how their story ended.
"Where they all went, we don't know," he said. "They probably scattered in all directions over time. By the mid 1300s, this site had been essentially abandoned."
The Mississippians lived here for hundreds of years, but Iseminger may be Cahokia's second-longest resident. He worked there as a graduate student, and then got the chance to come back.
"I was at an archaeological conference and talked to the guy who had been my supervisor when I was working here at Cahokia, and he said, 'How would you like to work at Cahokia?' I said, 'twist my arm.' And so I never thought about going any place else, and I've been here almost 40 years," said Isemenger. "People say… if you're doing what you like, why go anyplace else?"
An ancient culture by Western standards, and a history with a span as wide as these fields.
The Mississippians at Cahokia may have left here centuries ago. But because of Bill Iseminger and others like him, their memory lives on.