"Wal, Uncle George, was the Indian round?"

Like many traditional societies, the Mississippian culture was hierarchical, being comprised of three basic groups:  slaves, at the bottom of the society; the mass of common people; and a small elite class of religious and political leaders, probably hereditary in nature.  The Mississippians were later nicknamed the Mound Builders because they not only built burial mounds like some other American Indian societies, but constructed enormous temple mounds.  The Mississippian mounds were rectangular with steep sides and flat tops, like the pyramids in Mexico and Central America; yet were not similarly made of stone, but of log stairs and pole and thatch temples and residences (the higher the house, the higher the rank).

At Cahokia, about 120 earthen mounds, covering an area five miles square, supported the temples, residences, and burial grounds of the elite.  The central feature at the settlement was Monks Mound, which was the largest such structure in the pre-colonial era.  Taking an incredible amount of time and effort to construct (perhaps using slave labor), it covered 14 acres and rose 100 feet high.  

Indian mounds had long fascinated European Americans because they contained the human skeletal remains and artifacts of an ancient civilization.  American settlers and early archaeologists were most impressed by the size and engineering of the Cahokia mounds, but they often incorrectly concluded that the structures had been erected by a lost race of Indo-Europeans, rather than by the ancestors of Native Americans.  In 1857, Harper's Weekly reported, " We dash on impatiently over the broad 'bottom lands' of Cahokia, and past the gigantic mounds that stud its surface, some of which ... exceeding in cubic contents the great pyramid of Cheops [the Egyptian pharoah]-- the monuments of a race whose name is lost even to tradition ..."  Theorists speculated that the builders were the lost tribe of Israel, Egyptians, Phoenicians, Hindus, Welsh, or survivors of Atlantis.  A few suggested the Aztecs or Toltecs.  

The earliest European explorers had noted Native Americans building mounds, but racial prejudice may have clouded the judgment of later observers.  There were exceptions, however, such as Thomas Jefferson, who oversaw the excavation of a mound on his plantation at Monticello, Virginia, and duly chronicled the skeletal features and artifacts as similar to those of eighteenth-century American Indians.

The first excavation of the Cahokia mounds was conducted in 1883 by Thomas Ramsey, the owner of the land at the time.  His work was limited and imprecise, though, and a full-scale, scientific excavation of the site was not undertaken until the 1960s and 1970s by Washington University in St. Louis, the Illinois Archaeological Survey, and other teams of professional archaeologists.  They dated the settlement of the area by a group of native farmers to A.D. 800, and construction of the first stage of Monks Mound to A.D. 950.  Monks Mound was supplemented with higher and higher terraces over the years until reaching its present height around A.D. 1200.  

By the early-seventeenth century, Cahokia and other centers of the Mississippian culture had been abandoned.  The reasons are unclear, but may include crop devastation, overpopulation, intertribal warfare, or European diseases preceding European settlement of the American interior.  Today, Cahokia Mounds is an official Illinois State Historical Site, covering 2200 acres.