Tren a las Nubes, Argentina

Built 70 years ago, Salta, Argentina’s Tren a las Nubes is pretty up there, too. It operates almost 14,000 feet above mean sea level, which surely explains its name. (It translates to “train to the clouds.”) Using rack-and-pinion traction, the train traverses over 20 bridges, through 21 tunnels, and over 13 viaducts. Whew, we’re tired just writing that. The railway line spans 20 stops, with the average journey taking about eight hours. The kicker? It only runs once a week since it’s primarily a tourist attraction these days.