This thesis provides a systematic examination of two large circular post structures, the Great Post Circle and the Moorehead Circle, found in southwestern Ohio associated with Middle Woodland (200B.C.–A.D. 400) earthworks. Intra-site descriptive analysis of each structure's post architecture, artifact assemblages, interior features, and carbon dates provides the first opportunity for preliminary inter-site inferential analysis.

The Great Post Circle and the Moorehead Circle, located within five miles of each other, are ideal for inter-site comparison. Their associated earthworks represent the two recognizable styles of Ohio Hopewell earthworks, geometric and hilltop enclosures. They are both circular post structures that have been systematically investigated archaeologically, but documentation of both has been limited. The Great Post Circle was excavated as a salvage effort prior to construction, while the Moorehead circle is still in the early stages of exploration and analysis. This thesis focuses on an intra-site descriptive analysis investigating each structure's architecture, interior features, carbon dates, and artifact assemblages, which are then compared between the two sites to gain insight into this form of Hopewell monumental architecture.