From the 16th century, the mines of Potos , perched high in the Andes, bankrolled the Spanish empire. During those years immense wealth allowed the city to grow larger than London at the time and the mountain was quickly given the epithet Cerro Rico - the 'rich mountain'. But today, Potos 's inhabitants are some of the poorest in South America while the mountain itself has been so greedily plundered that its summit is on the verge of collapsing...