Shaker Lands in Harvard, MA

North of Rt 2 the hills and swamps, near the center of the Shaker historic area in Harvard MA, are full of rock piles. I stopped there on the way home from Groton where I made the mistake of planning a walk - it was a dud and I knew I'd find something, just driving around in that part of Harvard. 

Probably the most interesting thing during the weekend happened when I pulled to the side of the road and another car stopped in front of me and parked at the same time. I got out, looking inquisitive, and an elderly guy got out of the other car and asked me "is you car alright?", then "you aren't stealing rocks from the stone walls?", then I answered "of course not, I am taking pictures of them". After hearing that, the man goes: "oh. good, good....I didn't know about it but now I am in the know....". He seemed to be speaking about rock piles but I did not bother mentioning that I knew about them too. Just took pictures. It is certainly gratifying that a random old guy from Harvard knows about "hush hush....it is special". That would be near the lowest blue outline:

 Typically:

After that I walked around the edges of  a swamp and saw some other minor features at the upper blue outline.

 Witch Hazel is blooming:

I did find something unusual at the spot indicated with a red "?": an enclosure at the end of a wall.

This is shaped on the interior, very much like the chamber incorporated into a wall on Hubbard's Hill in Concord. But there is no evidence of corbelled roofing here.

And, also like similar enclosure from Lincoln [can no longer find the article], there was a bit of a niche or cupboard inside:

 from above

Having now seen two or three of these structures, I think there is a pattern here. These are not underground chambers, but not too different.