Église Saint-Sulpice

Saint-Sulpice, facing its own fountain-filled square in the 6th arrondissement, is the second-largest church in Paris after Notre-Dame. Construction began in 1646 and dragged on for over 130 years, leaving the two towers of its neoclassical facade visibly mismatched in style — the north tower was never completed to match the south. During the Revolution the church was repurposed as a Temple of Victory and later a storage depot before returning to Catholic worship. The interior houses one of France's grandest organs, associated for decades with composer Charles-Marie Widor. A brass meridian line inlaid in the floor leads to an 18th-century obelisk gnomon, a genuine astronomical instrument that tracks solstices and equinoxes — it predates Dan Brown's 'The Da Vinci Code' by two centuries, though the novel turned it into one of Paris's most Googled curiosities.