The Newark Earthworks are the largest set of geometric earthen enclosures in the world. Already a National Historic Landmark, in 2006, the State of Ohio designated the Newark Earthworks as "the official prehistoric monument of the state." Learn more about the earthworks by visiting the Great Circle Museum. Visitors are invited to watch an interactive video explaining the significance of the site and tour a 1,000-square-foot exhibit that includes a timeline of Ohio's ancient cultures and an explanation of why American Indians regard the Newark Earthworks as a sacred site. The exhibit also details how the earthworks align with the rising and setting of the moon. Following the museum tour, visitors can take self-guided tours of the grounds during daylight hours. Average visit time: Allow 1+ hours
While visiting Newark Earthworks, consider traveling 15 miles east to visit Flint Ridge [link to the Flint Ridge site page].
Built by prehistoric Hopewell Culture between 100 B.C. and 500 A.D., this architectural wonder of ancient America was part cathedral, part cemetery, and part astronomical observatory. The entire Newark Earthworks originally encompassed more than four square miles. Over the years, the growth of the city of Newark destroyed many of the Newark Earthworks, but three major segments survived because of the efforts of interested local citizens:
- Great Circle Earthworks: Formerly known as Moundbuilders State Memorial, the Great Circle Earthworks is nearly 1,200 feet in diameter and was likely used as a vast ceremonial center by its builders. The 8 feet (2.4 m) high walls surround a 5 feet (1.5 m) deep moat, except at the entrance where the dimensions are even greater and more impressive.
- Octagon Earthworks: Enclosing 50 acres, the Octagon Earthworks has eight walls, each measuring about 550 feet long and from five to six feet in height. The Octagon Earthworks are joined by parallel walls to a circular embankment enclosing 20 acres. At present the Octagon Earthworks is also the site of the Mound Builders Country Club golf course. Use care in viewing them. Guidelines are posted at the site.
- Wright Earthworks: This earthwork consists of a fragment of a geometrically near-perfect square enclosure and part of one wall that originally formed a set of parallel embankments, which led from the square to a large oval enclosure. Originally, the sides of the Newark square ranged from about 940 to 950 feet in length, and they enclosed a total area of about 20 acres.
While we can never know with any certainty the Hopewell’s purpose in designing the earthworks, one theory is that the Hopewell built these earthworks on such a massive scale for astronomical accuracy—long, straight embankments provide longer slight lines that increase the accuracy of astronomical alignments. In 1982, professors Ray Hively and Robert Horn, of Earlham College in Indiana, discovered that the Hopewell builders aligned these earthworks to the complicated cycle of risings and settings of the moon. They recovered a remarkable wealth of indigenous knowledge relating to geometry and astronomy encoded in the design of these earthworks. The Octagon Earthworks, in particular, are aligned to the four moonrises and four moonsets that mark the limits of a complicated 18.6-year-long cycle.