Oh! I'd love to have the chance to celebrate at Stonehenge! Or just walk there on a quiet day, to feel the energy without all the people. As for what we "should" do to celebrate, I think it's different for each person. For me it's another time to be in tune with nature and bless the land. I had a joyful day with my family, spent some time outside, hugged a few trees. @zen-art wrote a wonderful article about Beltane, as well, if you want to check that out you might find some ideas. ;) Brightest blessings!