No way, just three ?
No Boscawen un when it was more overgrown?
No swinside on the winter solstice?
No goosebumps at Brodgar?

It'll have to be these three classics then,
Uragh is small but the world is big,
http://www.themodernantiquarian.com/site/2560/uragh.html

Callanish is such a fantatic journey away that quite frankly they could have left the stones still half covered in pete and I would still be
blown away,
http://www.themodernantiquarian.com/site/198/callanish.html

La Roche au Fees on a warm summers afternoon with some kind of
summer fete on, playing children, lots of food and laughter, and right next to it all this sleeping giant that everyone took for granted but I drove
500 miles to see.
http://www.themodernantiquarian.com/site/9946/rocheauxfees.html

But theres so many places yet to see