Uyuni a small town situated in the middle of nowhere. It originally blossomed as a railroad junction, and even if this is still an important aspect, no doubt is tourism now its main source of prosperity. What would otherwise be a fairly dull stopover en route between Salta, Argentina and La Paz or Potosi, has become absolutely mandatory on this leg of the gringo trail. The sole reason: salt flats, the world's biggest. (See Salar de Uyuni).