America's Stonehenge is a site consisting of a number of large rocks and stone structures scattered around roughly 30 acres (120,000 m²) near the town of Salem, New Hampshire in the northeast United States. The origin and purpose of the structures is standardly attributed to a mixture of land-use practices of local farmers in the 18th and 19th centuries, as well as construction of structures by owner William Goodwin in the 1930s. However, a number of other hypotheses exist. Although the area was named after the archaeological site of Stonehenge in England, there is no actual connection between the two.
America's Stonehenge is open to the public for a fee as part of a recreational area that includes such things as snowshoe trails and an alpaca farm. It is a popular tourist attraction, with particular appeal to believers in New Age systems. Among several speculations put forward concerning the site's origins are claims that it could be an astronomical observatory built by some unknown, pre-Columbian civilization.
The site was first dubbed Mystery Hill by William Goodwin, an insurance agent who purchased the area in 1936. This was the official name of the site until 1982. The site was renamed "America's Stonehenge" (a term coined in a news article in the early 1960's) in an effort to separate it from the roadside oddity sites and reinforce the idea that it is an archaeological site.
Links: en.wikipedia.org, m.stonehengeusa.com