I love this site:
I'm sure many of you know of it already, but for those that don't....
It's a little clunky to figure out, but once you do, it's easy to use.
click on the type of megaliths you want to see on the map (cave systems, stone circles, etc.) then click "Initialize."
Thus will be revealed a map that shows all of the megaliths of that type in Europe (that have been registered with the site.) The map is always centered on England at first, but you can click on anywhere in the smaller Europe on the lower right, and see other parts of Europe.
If you see a marker you want to view, click "Query" in the upper right, and then click on the marker. Information will appear below the map.
Good stuff for inspiration!
Have a good one,