Ancient astronomical observatories (Stonehenge, Chichen Itza) may not be a good fit in the existing Astronomical Observatories category, which is intended for modern astronomical observatories.
As I've not been proactively involved in this site for a while, let's have some discussion.
1) Can a category have a sub-category in the newer releases of Waymarking? I've not followed the taxonomy discussions for over a year now, just been plain too busy.
2) Should there be a category or sub-category for Ancient Astronomical Observatories?
3) If "yes" to #2, who wants to launch the category?
az_pistolero