El Alto International Airport — La Paz / El Alto, Bolivia

Perched above the Bolivian capital at an elevation exceeding 4,000 meters, LPB ranks among the highest major commercial airports anywhere in the world, which forces airlines to adjust for thin air's effect on engine performance and takeoff distances. The airport sits in El Alto, a sprawling, fast-growing city on the altiplano above La Paz proper, connected to the lower-lying capital by road and, more recently, by an extensive cable-car transit system. Because thinner air reduces lift and engine thrust, aircraft departing LPB often must reduce their passenger or cargo loads compared with flights from lower-altitude airports, and the runway itself, one of the longest in South America, was built long to compensate. Visitors often notice altitude effects immediately, and La Paz's dramatic setting, ringed by the snow-capped Cordillera Real, makes for one of aviation's more striking approaches.