Sewell, a ghost town at 7,200 feet above sea level in the Andean foothills, was founded in 1903 as a copper mining town. One of its unique features is a lack of streets: Because of the slant on which Sewell was erected, inhabitants used stairs to get around. In its heyday, the town was home to miners who worked the world’s largest underground copper extractions. When Chile nationalized its copper industry in the late 1960s, part of Sewell was dismantled (the state could not afford the upkeep), but what remains—50 buildings—is now a UNESCO World Heritage Site. The official tour, which includes a meal just like one that the miners used to eat, takes a full day and is the only way to visit. Bring warm clothing no matter how balmy it is when you set off.