Hopewell Culture National Historical Park, cultural history site encompassing several groups of monumental earthworks of the Hopewell culture, dating between 200 bce and 500 ce, in south-central Ohio, U.S. The park was established as a national monument in 1923; it has undergone substantial expansion since its founding and now occupies an area of 1.8 square miles (4.7 square km). It includes the 24 conical burial mounds of the Mound City Group, on the west bank of the Scioto River just northwest of Chillicothe; the large, geometric Hopeton Earthworks, which are located across the Scioto River from the Mound City Group; and the Hopewell Mound Group, an extensively studied area on the North Branch of Paint Creek, west of the other earthworks. Numerous stone, bone, and pottery utensils, copper ornaments, and other artifacts have been recovered from the site, which was first explored in 1846.