Mercado Centenario is the practical stop that makes Tepatitlán feel lived-in. The lower level is for produce and household goods, while the upper level has prepared food, making it one of the better places in town for a simple breakfast or lunch.
It is not polished for visitors, and that is the point. Come before the churches if you want the city at its most awake, with vendors setting up and locals moving through their usual errands.