Lysefjord and Preikestolen. Photo Chaossart / Shutterstock Atlas Obscura put together a fantastic collection of buildings balanced on cliffsides . If you're afraid of heights, this is probably not a list you'd look at to plan your next vacation. If you enjoy hanging out on the edge of a treacherous-looking cliffside, this list will be right up your alley. The list includes Spain's Mohon del Trigo Observatory, an abandoned, mysterious-looking stone observatory sitting alone in the Sierra Nevada mountains. Then there's Arizona's Montezuma Castle National Monument, a 1,000-year-old cliff dwelling built directly into a limestone wall. There's also Iceland's Thridrangaviti Lighthouse, a tiny structure perched atop a jagged sea stack in the middle of the Atlantic Ocean that looks less like a lighthouse and more like a secret hideout. What ties these places together is the overwhelming feeling that humans absolutely should not have built anything there, and yet they did anyway.…