The ancient ruins of Cahokia are located in southern Illinois within the city limits of Collinsville. This places the ancient city less than ten miles from downtown St. Louis, Missouri just across the Mississippi River. Being so close to this major waterway had many advantages for the people of ancient Cahokia. For starters, the fertile floodplains of the river provided good land for farming. The Mississippi River also facilitated trade and contact with other peoples. Indeed, artifacts from all over the region and far beyond have been found at the site. In its day, Cahokia was likely the center of a large network of settlements of various sizes. At its height, the city of Cahokia itself probably encompassed as much as six square miles and was home to as many as one hundred thousand people in the thirteenth century.