Here is another view of that stone wall which was slightly north of a north-facing slope of the hill I explored last weekend near Gilmore Rd. Southborough, MA. You can see from the topo map placement of this feature that it runs southeast (118 magnetic) to northwest (295 magnetic) on a gradual slope beside the knoll defining the hilltop.
Here is how the lower end of the wall looks, nicely squared off.
If you look along the wall in that down-slope, northwesterly direction, you see what looks like another rock pile in line with the wall:Then going over to the pile and looking beyound it we see a few "natural" rocks continuing in that same direction.The rock pile consists of support stones holding up a flat "gunsight" with a small notch along its upper edge. From the side, you can see one of the support rocks is mostly made of quartz.
I have no doubt that this wall is ceremonial.