Great Serpent Mound

The Great Serpent Mound is a 1,348-foot (411-meter) prehistoric effigy mound in the shape of a serpent, standing about four feet high along Ohio Brush Creek in Peebles, Adams County, Ohio, on a plateau formed by an ancient meteorite impact crater. Built of yellowish clay and ash reinforced with rock and soil, it forms a triple-coiled tail and a head positioned beside an oval depression, and it is the largest serpent effigy known in the world. Its builders remain disputed: a 2014 radiocarbon study attributed it to the Adena culture around 300 BCE, while the archaeologist Brad Lepper has argued from artifact evidence that the Fort Ancient culture built it around 1070 CE. Designated a National Historic Landmark in 1966, the site is maintained today by the Ohio History Connection, and some researchers have proposed that its form carries astronomical alignments with the solstices and equinoxes.