Founded when the silver mines opened, Guanajuato had a symbiotic relationship with them up to the 19th century. Its growth, the layout of its streets, including the picturesque "subterranean" streets, its plazas, and the construction of hospitals, churches, convents and palaces are all inextricably linked with the industrial history of the region which, with the decline of the Potosi mines in the 18th century, became the world's leading silver extraction centre.