From the Mexico City Timeline, we learn that in 1730, Viceroy Juan de Acuña y Bejarano directed that all silversmiths in the city be moved to the Calle de San Francisco. Hereafter, the street was called Calle de Plateros (i.e.; Silversmiths Street). That name lasted until after the Mexican Revolution when it was changed again to Av Francisco I. Madero. This was in honor of the President, assassinated during the Revolution.
Today's Avenida Madero is the principle exit and entrance to the Zocalo. It's a thriving pedestrian-only street, nearly all day, every day.
The Avenida Madero area listings below are arranged such that you can get a good idea what you're passing. They're also intended to prevent you from passing up what you might really want to see.