CaptionThe indigenous people of Cerro Rico use tools and techniques similar to those used by their ancestors. Cerro Rico, 'the rich mountain', in the Bolivian highlands, is like a rabbit warren. In Spanish colonial times this was a thriving city. At the time half of all silver ever mined originated from here, but the mountain is also the grave of millions of Quechua Indians. Their descendants still go down the mine shafts. They now look for tin, because most of the silver is long gone.