The entrances to the mounds at Knowth line up with the autumn and spring equinoxes and the mound is 1.5 acres. The Newgrange entrances line up with winter and summer equinoxes.
These mounds hold over 50% of all the Neolithic art in western Europe. You can walk into the burial chamber at Newgrange and the passage is 19 meters long. Inside are alters and granite basins too large to fit through the stones, so the entire structure was built around them.
Time to head to the coast, sit bones protesting the bike seat, I managed to go about 50 miles to Carlingford and a beautiful camp on the beach.