Let me continue posting about the site I discussed earlier [click here], an area in Hopkinton of small knolls and wet spots and small rock piles clustered around and among the knolls. There were what looked like small enclosures in a few places on the knolls giving a sense of being places to look outward from.
You can see a kind of "U" shaped enclosure, right of center, opening towards the camera. A line of rocks leads off downhill to the left. Here is a view from the side of those rocks:There is a small rock pile at the lowest point (on the right in the picture) and you can also make out a few other placed rocks above it. Here is a view back up the line of rocks, we are looking back up towards the enclosure:
There were similar structures in a couple of places built into the outcrops. Here is the suggestion of something built into the outcrop:Here was another:
A closeup helps show this is an artificial structure:It is not certain that these constructions were used to look outward but it is consistent with the many small rock piles scattered around and the possibility that the piles were seen from above and used as positional markers. Looking back through the pictures, I also see several split rocks that seem to be part of the deliberate manipulation.