There's a World Heritage site north of Dublin called Bru na Boinne where there are the remains of passage tombs dating back some 5000 years to the Neolithic age. These tombs are older than the pyramids of Egypt! There are three major tombs in this area Newgrange, Knowth and Dowth. I toured Knowth. It was pretty cool to think I was standing in the midst of buildings that were used for ceremonies in communities over 5000 years ago. Incredible. Knowth itself also had some pretty interesting Neolithic art (always a favorite) and we got to enter into the largest mound. I liked the way the light played on this passage way above.