In our culture, we often say people who live in glass houses shouldn't throw stones. But in Iceland, Nordic islanders don't throw stones because they might hit the Huldufolk, or hidden people. These enchanted, beautiful (and some say imaginary) beings live in large rocks, rock piles and outcroppings in Iceland's startling dramatic landscape. Sometimes construction projects are rerouted around rocks where Huldufolk are thought to live; other times, seers are hired to advise builders and designers where Huldufolk rock dwellings could be moved without angering them. I might pick this majestic outcropping in Thingvellir National Park, not far from a waterfall where Game of Thrones was filmed.  I'd use the keyhole-shaped opening as my widow's walk.