The Great Serpent Mound is a curvilinear burial mound in the shape of a curling snake located in the southern portion of Ohio. This monumental earthwork is nearly a quarter of a mile long and is still clearly visible. The Great Serpent Mound was at first attributed to the Adena culture, which flourished in the early Woodland Period (c. 300 B.C.E.-1000 C.E.), and was known for building monumental mounds used for burial. The site is now thought to be the work of the slightly later Mississippian culture and has been dated to around 1070 C.E. Serpentine forms appear on other types of Mississippian art, and serpents (as in many other cultures) were associated with fertility and harvest. Some scholars, however, believe that the shape of the Great Serpent Mound mirrors the path of Halley’s Comet, which was visible in the year 1066 (The Bayeux Tapestry also records this event).
The exact purpose of monumental earthen mounds such as Monks Mound in Cahokia, Illinois, built by the Mississippian people hundreds of years before Europeans sailed to the Americas, remains unknown.