The Octagon Earthworks consist of a circular earthen enclosure connected to an octagonal enclosure by a short segment of parallel walls. The Octagon Earthworks formed one part of the Newark Earthworks, the largest set of geometric earthworks built by the Hopewell culture (100 B.C. to 500 A.D.) of pre-contact American Indian people. The circle encloses about 20 acres and the octagon about 50 acres.
Ray Hively and Robert Horn, of Earlham College, believe that the Octagon Earthworks served as a sort of astronomical observatory. A line extended through the center of the circle and octagon points toward the place on the horizon where the moon rises at its northernmost point in a cycle of moonrises that takes 18.6 years to complete. Other moonrise and moonset alignments also are present in the architecture.
The citizens of Newark and Licking County preserved the Octagon Earthworks by giving the site to the State of Ohio for use as a summer campgrounds for the Ohio National Guard. In 1910, Moundbuilders Country Club established a golf course in the area. Since 1933, the Ohio History Connection (then, the Ohio Historical Society) has owned the site, but it still is managed and operated as a private country club.
The Octagon Earthworks, as part of the Newark Earthworks, are a National Historic Landmark. The Octagon Earthworks site is located at North 33rd Street and Parkview Road on the west side of Newark, in Licking County, Ohio.
- Byers, A. Martin. The Ohio Hopewell Episode: Paradigm Lost and Paradigm Gained. Akron, OH: University of Akron Press, 2004.
- Carr, Christopher, and D. Troy Case, eds. Gathering Hopewell: Society, Ritual, and Ritual Interaction. New York, NY: Kluwer Academic/Plenum Publishers, 2005.
- Dancey, William S., and Paul J. Pacheco. Ohio Hopewell Community Organization. Kent State University Press, 1997.
</span /> </span />
- CERHAS. EarthWorks, Virtual Explorations of the Ancient Ohio Valley. The Center for the Electronic Reconstruction of Historical and Archaeological Sites (CERHAS). Cincinnati, OH, 2006.
- Pangea Productions. Searching for the Great Hopewell Road. N.p.: Pangea Productions, 1998.
- Case, D. Troy and Christopher Carr, eds. The Scioto Hopewell and their Neighbors: Bioarchaeological Documentation and Cultural Understanding. New York, NY: Kluwer Academic/Plenum Publishers, 2008.
- Earthworks Virtual Explorations of Ancient Newark, Ohio. The Center for the Electronic Reconstruction of Historical and Archaeological Sites. Cincinnati, OH: Center for the Electronic Reconstruction of Historical and Archaeological Sites, 2005.
- Warriner, Gray, producer. Legacy of the Mound Builders. Seattle, WA: Camera One for the National Park Service and the Hopewell Culture National Historical Park, 1994.
- Woodward, Susan L., and Jerry N. McDonald. Indian Mounds of the Middle Ohio Valley: A Guide to Mounds and Earthworks of the Adena, Hopewell, Cole, and Fort Ancient People. Lincoln: The University of Nebraska Press, 2002.
- Hively, Ray and Robert Horn. "Geometry and Astronomy in Prehistoric Ohio," Archaeoastronomy, Volume 4, S1-S20. Supplement to Journal for the History of Astronomy, Vol. 13, 1982.
- Lepper, Bradley T. "The Newark Earthworks: Monumental Geometry and Astronomy at a Hopewellian Pilgrimage Center", in Hero, Hawk, and Open Hand: American Indian Art of the Ancient Midwest and South, edited by Richard V. Townsend and Robert V. Sharp. Art Institute of Chicago and Yale University Press, 2004.
- Lepper, Bradley T. Ohio Archaeology: An Illustrated Chronicle of Ohio's Ancient American Indian Cultures. Wilmington, Ohio, Orange Frazer Press, 2005.