Great Serpent Mound, Ohio
Serpent Mound is an internationally known National Historic Landmark built by the ancient American Indian cultures of Ohio. It is an effigy mound (a mound in the shape of an animal) representing a snake with a curled tail. Nearby are three burial mounds—two created by the Adena culture (800 B.C.–A.D. 100), and one by the Fort Ancient culture (A.D. 1000–1650).