Where are the rock piles on Boston Hill?

A reader once wrote that Boston Hill in Westborough had rock piles. It is a bit of a drive from here, almost in Shrewsbury, but it is a huge hill, overgrown and hard to explore, and I did not find rock piles. I was not sure where to go and gave up after a while. There was some obvious ceremonialism: Also some possible ceremonialism: But where were the rock piles? I have forgotten who told me about Boston Hill, so if anyone knows the answer, I'll try again - even if it is a bit of a drive.