At its peak around 1200 CE, the ancient Mississippian settlement of Cahokia stretched nearly six square miles, from what is now East St. Louis, Missouri, to Collinsville, Illinois, and included around 120 man-made earthen mounds. It was as large, or larger, than any European city of that time, but can we fairly or accurately call Cahokia a city? John Kelly, senior lecturer of archaeology at Washington University in St. Louis, discusses the limitations of imposing the Western concept of "cities" on ancient sites and describes the mound culture of Mississippian Native American clans. Today, Cahokia Mounds is still considered the largest and most complex Pre-Columbian archaeological site north of Mexico.