This spot in New Hampshire has been on my list to visit since I read an article in Yankee Magazine about it. [Latest article here.]
Once called Mystery Hill, it's been open to the public since 1958. Though you can download an app to give you an oral tour, we opted for the printed version. The labels and trail have the tired look of having been in place since the 50s, but despite that it was a fascinating walk through some history. Questions remain as to how ancient it really is.
This standing stone is in alignment with the center of the site. You can see the viewing platform in the background. I don't know whether this is for summer or winter solstice or an equinox. It is quite impressive to see all the points in the distance from the viewing platform.
Google America's Stonehenge to read more about this site. Fascinating to consider what civilization created it originally.