For decades, the stone cave or chamber at 18 Elm Street, near the eastern shore of Mill Pond, has intrigued and puzzled Upton residents and others who have studied its construction and possible origins.
Was it built by pre-Columbus European explorers? By Native Americans as a spiritual site? By early American farmers for agricultural purposes? By a 19th-century leather tanner? Each theory has its advocates.
The Upton Cave has been described as one of the largest and most perfectly built of more than 300 stone chambers found throughout the Northeast. A six-foot-high, fourteen-foot-long tunnel leads into a hillside, to a beehive-shaped domed chamber of quarried stone measuring about twelve feet across and eleven feet high. The cave is topped with several large oval stones believed to weigh several tons each.
As the exploration of its past continues, the future preservation of the cave seems assured. Upton residents voted to preserve the historic stone structure and its setting by acquiring the seven-acre property on Elm Street for a community park using Community Preservation Act funds.