"Some two and a half hours north of the Argentina/Bolivia border is Tupiza. It's a pleasant town (population 20,000) at just under 3,000 meters, so it's not as taxing on the lungs, nor as cold as places like Uyuni on the altiplano. It is set in a landscape of bright green valleys beneath richly colored mountains. As a base for exploring it couldn't be better. There are good walks, bike rides and jeep trips.
From Tupiza, agencies make tours into the famous Salar de Uyuni, the largest salt lake in the world, and the neighboring Eduardo Avaroa National Reserve, which contains some of Bolivia's most beautiful high-altitude lakes and stark volcanoes."
View of the salt flat of the Salar de Uyuni is displayed with the kind permission of Peter and Jackie Main. For more images, see the photographic tour of the Salar de Uyuni.