Rock piles by a swamp by the highway - Rt 495 Harvard

Walking in Harvard is great when you can find un-disturbed woods. Here are some panoramas of the site next to that swamp I talked about here.
Another:
The piles were mid-sized with large rocks, and they looked like they were evenly spaced, suggesting a calendrical use.

Let's have that owl again, which I saw on the way out.