> They aren't "all over the place" in the US, and I certainly don't have a local archaeologist that I can just call up… The Northeastern US is quite recent with human presence

Fun fact, New England has at least 71 different stonework “prayer sites” that are all astrologically aligned.

Two of the most notable are King Philip’s Cave (Sharon, MA) with a stone aperture through which a "dagger of light" appears specifically during the winter solstice, and Pole Hill (Gloucester, MA) which has fixed boulders that align with the summer solstice sunrise/sunset and the winter solstice sunrise.

Here is a research paper talking about all of them: https://neara.org/pdf/wantofanail.pdf

There are lots of historical preservationists in New England that you can call up. If you want my help finding one let me know where you are located.