Boliva - City of Potosí

"In the 16th century, this area was regarded as the world’s largest industrial complex. The extraction of silver ore relied on a series of hydraulic mills. The site consists of the industrial monuments of the Cerro Rico, where water is provided by an intricate system of aqueducts and artificial lakes; the colonial town with the Casa de la Moneda; the Church of San Lorenzo; several patrician houses; and the barrios mitayos, the areas where the workers lived." 
Source: UNESCO World Heritage