El Alto (Spanish for The Heights) is the second-largest city in Bolivia, located adjacent to La Paz in Pedro Domingo Murillo Province on the Altiplano highlands. El Alto is today one of Bolivia's fastest-growing urban centers, with a population of 974,754 in 2011. El Alto is the highest major metropolis in the world, with an average elevation of 4,150 m (13,615 ft).
The El Alto-La Paz metropolitan area, formed by the cities of El Alto, La Paz, and Viacha, constitutes the most populous urban area of Bolivia, with a population of 2.3 million inhabitants (greater than the metropolitan area of the country's largest city of Santa Cruz de la Sierra).