Potosi in Bolivia was the largest mine, and Zacatecas in Mexico, resulted in the creation of wealthy urban centers. Indians worked the mines. Potosi has the big red arrow pointing to it in this map of Bolivia.
La Paz, Bolivia, highest capital in the world! The altitude of La Paz will literally take your breath away. I remember one Sunday sitting in a sunny park and got a serious sunburn on the ball of my head.