The Great Serpent Mound as seen from the observation tower
The Great Serpent Mound was constructed by an unknown people in an unknown time for an unknown purpose. The only truth behind the mystery is the location of the effigy mound, near the edge of a five mile wide geologic disturbance in Adams County, Ohio.
Adena burial mound near the museum
The presence of this mound alludes to the fact that the park surrounding the Great Serpent Mound was an important site for numerous cultures of First Ohioans, including the Fort Ancient culture. A smaller, and much more rare, Fort Ancient mound is also located within the park. The Ohio historical marker at the site notes that the Fort Ancient culture is responsible for the construction of the Great Serpent Mound, however, that erroneous statement is based on the removal of Fort Ancient period charcoal fragments from the mound. Since several different cultures may have used the Great Serpent Mound as a ceremonial site, the presence of charcoal simply indicates that the Fort Ancient people were present at the site around 1000 A.D.
Mound City contains the highest concentration of burial mounds in Ohio (23 mounds). The Hopewell site is one of three sites open to the public in the Hopewell Culture National Historic Park (the other two are Seip Mound and the Hopewell site).
The two classic shapes of Hopewell burial mounds can be seen at Mound City. Some propose that the round-shaped and loaf-shaped mounds were built to emulate the two essential forms of Ohio's foothills. The nearly perfectly rounded hill known as Sugarloaf (part of Great Seal State Park) can be seen in the distance from within the enclosure at Mound City.
Seip Mound is a massive Hopewell burial mound in the Paint Creek Valley of Ross County. Thousands of freshwater pearls were included with the burials in this mound. The mound was originally the centerpiece of a geometric earthworks enclosure.