Potosí is the an outstanding example of a major silver mine of the modern era, reputed to be the world’s largest industrial complex in the 16th century. A small pre-Hispanic-period hamlet perched at an altitude of more than 13,000 ft (4,000 m) in the icy solitude of the Bolivian Andes, Potosí became an "Imperial City" following the visit of Francisco de Toledo in 1572.