Claim: Portsmouth Earthworks City of Portsmouth maintains a public park and was listed on the National Register of Historic Places in the early 1970's.
Evidence: The City of Portsmouth maintains a public park which includes one of the remaining horseshoe-shaped enclosures, known as Mound Park, it is the only publicly accessible part of the complex. Under the name Horseshoe Mound it was listed on the National Register of Historic Places in 1974.