Williamson Mound State Memorial
Why it's listed
Williamson Mound is a large Adena burial mound on a grassy rise above Massie Creek, near Cedarville in Greene County, Ohio. It now stands 27.5 feet high and about 150 feet across. The mound was probably built toward the end of the period between 500 B.C. and 400 A.D. It was given to the Ohio Historical Society in 1929 in three tracts, after which it was restored to its original shape, covering scars left by earlier explorations, including those of Squier and Davis in the 1840s. The nomination considers that digging to date was slight compared with the size of the mound. If the mound was raised over a long span of time, a full excavation might show changes in burial customs and in the everyday lives of the Adena people. The mound is regarded as likely to prove important archaeologically. The owner authorized transferring the site to the Greene County Park District as part of a new county park.
Significance in brief: The nomination describes it as a large Adena mound that is likely to prove important archaeologically once fully excavated. Earlier digging was probably slight relative to the whole mound. If it was built over a long time, excavation could reveal changes in both burial practices and the daily life of the Adena people.
Machine-generated summary. This summary was generated by a language model from the official nomination document and has not been reviewed line by line by an editor. It may contain errors. Check the source document before relying on any detail. Source: nomination document (PDF) · National Archives catalog entry. NRHP reference 71000639, listed December 13, 1971. Summary generated October 2026 (model claude-sonnet-5-5, prompt v1.0-2026-10-29, confidence medium).
Key facts
| Address | Off OH 42, Cedarville |
|---|---|
| County | Greene County |
| Listed | December 13, 1971 |
| Reference number | 71000639 |
| Resource type | Site |
| Period of significance | 500 B.C.-400 A.D. (Pre-Columbian) |
| Areas of significance | Prehistoric |
| Level of significance | State |
| Status (as stated in the nomination) | Condition listed as excellent; restored after earlier excavation scars were covered. Owned by the Ohio Historical Society, with a proposed transfer to the Greene County Park District. Form marks the site as unoccupied and as a park. |
| Acreage | 1.7 |
| Coordinates | 39.74499, -83.82679 (NPS GIS) |
What listing means for this property
Sites (archaeological sites, battlefields, landscapes) are often listed with a restricted address to protect them from looting or disturbance. Listing is honorary for private owners; federal undertakings on or near the site go through Section 106 review, and state laws may protect burials and artefacts regardless of listing.
General information, not legal or tax advice. Rules change; confirm with your State Historic Preservation Office or a qualified adviser.
Sources and further reading
- National Park Service, National Register of Historic Places database (snapshot May 2026), reference 71000639.
- Nomination form (PDF, National Archives) — catalog entry
- Wikidata Q115110581
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.