Adena Mound, on the grounds of the Adena Mansion near Chillicothe, Ohio, is a Native American archaeological site and the type site for the Adena culture, a precontact mound-building tradition that took its name from this place. Carbon dating indicates the mound was built between 100 B.C. and A.D. 40. Before excavation it stood 26 feet high, dominating the surrounding landscape. William C. Mills, Ohio’s state curator of archaeology, excavated it in 1901 and uncovered jewelry, projectile points, textiles, and the Adena Pipe, later named Ohio’s state artifact. Its archaeological importance was formally recognized with National Register listing in 1975.