Disillusioned by the horrors of Cerro Rico's mines and the callous greed of their families, a number of Potosí's young women renounced the world by entering into the Convent of Santa Teresa. They would never again step outside its walls. We were pressed for time, and told our guide that we wanted just a quick tour. But the convent's history was simply too fascinating, and we ended up spending about two hours inside. Santa Teresa was established in 1685, providing a home to a sisterhood of Carmelite nuns. It's still active today, but its numbers have dwindled significantly, and most of the immense complex is now a museum.