You don't have to be religious to enjoy the tranquil atmosphere of Nancy Cathedral. Inquire when the next mass starts or when it's open for general viewing.
This principal church is often on the itineraries of travelers to Nancy City Centre. But Nancy Cathedral isn't the only highlight in the area. Place Stanislas, Musee des Beaux-arts, and Musee de l'Ecole de Nancy are some other worthwhile attractions close by.