Serpent Mound is n. on SR 41, then 4 mi. n.w. on SR 73. One of the finest remaining prehistoric Native American effigy mounds, this immense earthwork's sinuous curves lie on the crest of a ridge paralleling Ohio Brush Creek. The archeological feature is nearly a quarter-mile long and is 5 feet high. The head of the serpent is aligned to the summer solstice sunset. A museum features exhibits about the earthwork and the local geology of an ancient cryptic explosion.