The outer embankment of this earthwork was constructed about 160 B.C. by the Adena people. Later, the Hopewell people added a small mound containing four human skeletons, cremations, bone awls, pottery shards, projectile points and a platform pipe that were excavated during the summers of 1968 and 1969. However, it is believed that the main function of the Great Mound was as a meeting area for religious ceremonies. The gateway provided access to the central platform where the ceremonies took place. The outer ring could have served as a seating area, but was probably constructed to block any viewing of these ceremonies from others.
The Adena and Hopewell people reached their peak between 200 B.C. and 300 A.D.
The Great Mound is the largest surviving of its kind in Indiana. More than 16,300 cubic yards of soil were moved in its construction.