Ancient Native American city may have been done in by Mississippi floods

Long before Europeans arrived to settle St. Louis, an impressive human construction stood on the eastern side of the Mississippi River. It was the Native American city of Cahokia. At its height, tens of thousands lived in and around Cahokia, leaving behind great earthen mounds as testament. The largest still stands about a hundred feet tall today, minus what was likely a temple that once adorned its crest.