Guanajuato is a mining town, at one time the richest town in all of New Spain and after Mexican independence. They originally put Rio Guanajuato under the town, then rerouted it altogether after a bad flood. They built more tunnels for car traffic, and today the tunnels are fairly well used, although there is a lot of car traffic on the surface.
It was reassuring to see that the town is well supplied with Diet Coke, my preferred caffeine vehicle.
Por favor, un Coca "light."