The Potato Cave is an underground chamber in Acton, named this way because of the assumption that this is a colonial root cellar. It is a dry stone structure built without mortar in a post-and-lintel style: with vertical support walls and large flat cap stones bridging straight across between the walls. On the outside all you see is a fern covered mound and a dark hole. The stone over the door is falling down and this chamber is not in good shape.

The Potato Cave is part of the town of Acton's "Nashoba Brook Conservation Land". To get to it go east on Rt. 27 from Rt. 2A, right on Northbriar, take the next right and go to the end of the street. Park and walk over the hill and down along the property boundary, at the bottom go right 20 yards and look to the right. If you visit it, please respect it's fragility.
 

You go in and see more damage along the left wall. You proceed inward for 10 feet and then turn right into a side area. The plan is of an up-side-down "L" with the entrance at the bottom of the main stem. It is a good idea to have a candle, or a flashbulb on your camera, because it is very dark with your back to the entrance.
 

Archeologist Mark Strohmeyer of Arlington first publicized the Potato Cave because of his belief that it is pre colonial or at least not colonial. The architecture is similar to some Neolithic chambers in Britain, and when he sat inside the chamber at sunrise on the winter solstice (December 21), he saw what he was hoping to see: The first rays of light entered the chamber through a small triangular opening to the side of the entrance. When the first ray of light enters, it falls against the back wall where it tracks along the edge of a lighter diamond shaped rock, and then vanishes. You can see the triangular opening in the picture. There is a similar feature next to the entrance at Newgrange in Ireland.

Whatever the origin and age of this structure it is a unique location in Acton. There is supposed to be another underground chamber in Concord, in Estabrook Woods. There are probably thousands of such structures in New England and eastern New York state but they are being destroyed at a rapid pace by development. To dismiss them as "just colonial root cellars" is at best an injustice to the colonial farmers (since the construction is beautiful); at worst it may be ignoring an extraordinary pre historical resource. These chambers need protection from an uninterested and unaware community.