An earthen embankment nearly a quarter-mile long is the largest and finest serpent effigy in North America. The mound represents a giant uncoiling snake. Archeologists don't know which of the area's prehistoric cultures built the effigy, or why. The details are a mystery! Serpent Mound has lunar, solar, planetary, and celestial alignments. It marks all the solstices and equinoxes by lunar or solar alignments or both. In 2005, a local research team observed a triple alignment during the Summer Solstice Sunset. The moonrise was in the opposite direction and Venus set in the same area as the sun, all happening in secession. Later that year, the Volunteers of Serpent Mound honored the Winter Solstice by placing over 900 luminary bags along the edge of the effigy, producing a holiday glow. The grounds are open every day of the year from sunrise to sunset, except during severe snow or ice conditions. Please check Adams County Travel's Serpent Mound page for more information.