Bolivia’s Salar de Uyuni is the largest salt flat in the world (4,086 square miles), an endless sheet of hexagonal tiles (created by the crystalline nature of the salt), dotted with pyramids of salt. During the wet season, it is transformed into a salt lake, only six to twenty inches deep, and perfectly mirrors the sky, creating illusions of infinity. It contains an estimated 10 billion tones of salt, of which less than 25,000 tonnes is extracted annually. The large area, clear skies, and exceptional flatness of the surface make the Salar ideal for calibrating the distance measurement equipment of satellites. In the middle of this infinite salty lake is a hotel built entirely out of — naturally — salt!