I should mention Newgrange since it's the Winter Solstice currently . It's one of the coolest places I've ever been. I saw it when I was 17 on my trip to Ireland. It's an ancient Celtic burial mound which predates the pyramids in Egypt, and is covered with neolithic markings and decorations the meaning of which is still a mystery to archaeologists. The coolest feature is the fact that during the winter solstice sunlight enters through a "roof box" and illuminates the chamber.
I love Pagan astronomy. If you would like to be there for the Solstice you can actually enter the yearly lottery, but you know...good luck!