Throughout most of the nineteenth century, it was believed that the tens of thousands of earthen mounds that dotted the central United States were engineering feats created by a mysterious, lost race - a race that had been destroyed by the less civilized Indians. Poet William Cullen Bryant, in 1832, expressed the sentiment of the period:

The red man came, The roaming hunter tribes, warlike and fierce, And the moundbuilders vanished from the earth.

By the late 1880s, it was becoming clear that the mounds were actually built by ancestors of the numerous native American groups that still inhabited the central states, such as the Natchez. This film reconstructs the history of ideas associated with the mounds and their builders, from the mid-nineteenth century explorations of curious citizens, to contemporary archaeological research in the Illinois River Valley. It is now known that there were at least two major mound-building cultures: the Hopewell, which flourished between 300 B.C. and 300 A.D., and the Mississippian, which peaked around 1200 A.D. Hopewellian mounds are usually conical, earthen structures concealing burials in which marvelously carved stone pipes and mica cutouts are found along with skeletal remains. The later Mississippian mounds tend to be square or rectangular, massive, flat-topped, mesa-like platforms on which houses or temples were erected. Archaeologists believe that a shift to settled maize agriculture had occurred by the time the Mississippian cultures appeared. Such an economic base permitted the growth of veritable metropolises, such as Cahokia, near East St. Louis, where the largest mound stands 100 feet high and covers an area of almost 15 acres. At Cahokia, over 100 mounds formed the heart of a city-state that may have had a population of 20,000 and dominated an area about the size of New York State.