A special place in Groton

Although I say Groton is in the category of "always disappoints" there are actually a few sites here and there. I joke that the only good sites in Groton are in adjacent towns: Horse Hill should really be in Dunstable, Snake Hill should really be in Ayer. Except for a little bit of northern slope down hill from "The  Throne", I don't know any sites in Groton with larger "mounds".

But I still spend time exploring Groton. It is not too far away and has several patches of woods that look ok on the map. Long ago I explored off the end of Nutting Rd and a place called "Smoke Hill" with a friend. We didn't see anything interesting and never went back. Recently I woke up thinking I had missed a spot on the map south and east of the end of Nutting Rd. So I went for a quick walk and saw a few things. Let me tell you about a little valley I found between Smoke Hill, Rocky Hill, and Snake Hill:

It is a little bowl where the waters from the higher marshes drain out in a small brook going over little cascades that fill the bowl with sound of gurgling. As I approached, I could hear this sound from dozens of little waterfalls.

 

I say: "What looms there in the distance?" The view (look in the upper 1/3 of photo):

As I went to take a closer look, I found a "niche" with an opening through to the downhill/water side of the structure:

 

The lintel stone is notable:

I regret not examining the opening through the structure more carefully.

Quite a fine structure.

There was a loose stone wall crossing the slope in a diagonal from the top of the brook over towards the "niche" but I did not see any other man made structures here. So I went up to see where the water was coming from: