Église de la Madeleine is one of Paris's great architectural surprises: a Catholic church dressed as a vast Corinthian temple. Begun in the 18th century and only consecrated in 1845, it carries the grand, theatrical confidence of imperial Paris on the outside and a rich interior of marble, gilding, and devotional sculpture within.
It is an easy stop between the grands magasins, Place de la Concorde, and the Opéra district. Step inside even if you only have ten minutes; the contrast with the classical facade is the point.