Ok, here goes:

Joint 3rd - Swinside stone circle / Stoney Littleton long barrow (can't separate them)

2nd - Castlerigg - those views!!!

1st - Avebury. I know this is a 'cheat' as I am inlcluding the circle, avenue, West Kennet Long Barrow and of course Silbury Hill. Avebury is simply magical.

As I am off to the Orkneys in the summer this list may change?!!