San Pedro de Atacama

San Pedro de Atacama needs 3 days: the Valle de la Luna, with salt and clay formations resembling a lunar landscape, on one, the El Tatio Geysers, active at dawn at 4,300 meters altitude, on another, and the Atacama Salt Flat with its high-altitude flamingo lagoons on the third. October-March is best, avoiding the extreme cold of the highland winter. It's expensive by Chilean standards, with organized excursions accounting for much of the spend. It's the gateway to the driest desert in the world -some areas have never recorded rainfall-, and its sky, among the clearest on the planet, is home to some of the world's most important astronomical observatories.