Serpent Mound is the largest "serpent effigy" known to man.  Historians have generally believed that the mound was build by the Adena culture (800 BC-AD 100). Two nearby burial mounds are also attributed to this culture. A third burial mound can be found at the at the Serpent Mound State Memorial and a village site near the effigy's tail belong to the later Fort Ancient culture (AD 1000-1550).  Recently some historians have begun to suspect that the Fort culture may have been responsible for most of the creations at the site.