The first city I stayed in during my recent November trip to Mexico was Guanajuato. The city has a distinct New Spain-feel due to its history of being home to major silver mines. The town is home to a rich, wonderful history and has been one of the few major centers of learning outside Mexico City for most of Mexico's history.
A combination of its scientific reputation, wealth, and geography led Alexander Von Humboldt to visit the city in 1803. Von Humboldt explored the mines on the ridge overlooking the city in the bowl valley below. He was surprised to see such wealth in an arid land that only had "miserable" Indian villages scattered throughout the area (This is not to say Von Humboldt was a racist. As he wrote later on that the wealth earned from the mines needed to benefit not only the Whites but also the Indians and Mestizos). A month of exploring the desert and mines around Guanajuato led Von Humboldt to declare his stay there one of the most exhausting of his life. That would be quite a feat for the city especially since one realizes the size of his Latin American trip.
The trip throughout the New World was a success. Von Humboldt wrote works on the interrelationship between geography, the environment, and biology. His works made the modern field biogeography. Besides his biogeography gift to academia, his works were used by Spanish and other New World farmers to greatly improve productivity.
Von Humboldt's time in Guanajuato was short but the city, realizing the greatness of the man, gave the geographer his own street and properly remembered his visit two hundred years later.