The Ohio State University's Newark Earthworks Center will hold an open house with guided tours and activities from 1 to 4 p.m. Grounds will be open from sunrise to sunset. It is the final day of full public access for 2016.

The Newark Earthworks, of which the Octagon Earthworks is part, was built 2,000 years ago. According to the Ohio History Connection, it is the world's largest set of geometric earthen enclosures and is a National Historic Landmark.

The Newark Earthworks Center conducts programs and research about earthen architecture to promote an understanding of American Indian histories and cultures in the Great Lakes region.

The Octagon Earthworks is at 125 N. 33rd St. For more information, go to newarkearthworkscenter.blogspot.com.