Burg Eltz Castle overlooking the Moselle River between Koblenz and Trier, Germany. I was in Trier once but only for a day and we didn't get a chance to go to the castle. I've been wanting to go back to Germany ever since.
France. Labyrinthe de maïs de Cordes-sur-Ciel, Tarn // Yann... (Arc of the World)
I did this! the BOB (Breathing Observation Bubble) scooters in St John, Virgin Islands. Easy to do and a diver stays with you to keep you on the path. You are 17 ft under water, scooting over shipwrecks, coral and through schools of fish.