|only after appointment, special occasions 
|none, bring torch
|L=3.35 m, W=2.74 m, H=2.74 m.
|Acton Memorial Library, Tel: +1-978-264-9641.
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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The Nashoba Brook Stone Chamber is an L-shaped, man-made room, 3.35m long, 2.74 m wide and at its highest point 2.74 m high. It is constructed of local stones of extraordinary size, the ceiling is constructed by only five about 10 cm thick slabs weighing about one ton each. It is entered through a narrow and steep 5.18 m long staircase. The chamber is located in the Nashoba Brook Conservation area in the town Acton, built into the forested bottom of a small hillside at the Nashoba Brook.
This structure is not the only one of its kind, 350 to 400 similar subterranea were found all over New England. But it is the only one located at Acton. We categorized it as a cellar, but we do not know this. Although rather similar, we do not know the origin nor the use of those structures. The enigmatic rock structures, often with surrounding surface rock structures are so far not explained by science.
The problem with such structures is, that there is no way to date them by physical methods. The only way is to date content of the chambers, then it is possible to say they are at least as old as the content. But so far no content of the original creators was found. And as a result there are hundreds of theories for every possible age. The most probable explanation is, they were built by early settlers as cellars to store food and probably valuables. Others say they were created by local Red Indian tribes hundreds of years earlier. Probably for ceremonial purposes, the Nashoba Praying Village was not far away, in todays Littleton.
But there are many other theories, some say, they resemble Maya structures and are probably a thousand years old. And there are theories about an ancient people which lived here before the Indians, probably during the Megalithic Era. However, this far past is not well documented in Northern America, there are doubts how early and how intensive the continent was inhabiited by man. And finally there are the ufo believers and esoteric guys who theink they were made by aliens or gods.