gee whiz, too many to mention. But one I have only been to once   and want to visit again: a round barrow covered with beech trees just off the Ridgeway Track between Avebury and West    Kennet, England...
It's beautiful to behokd from a distance (there is in fact a   photograph of it in the National Trust Book of Long Walks, and when upclose it has an eerie but calming and comforting stillness. a friend and I took an afternoon nap there once before we knew it was a barrow...