You can't miss the unusual lacy spire of this church as you approach the Ile St-Louis; it's the only church on the island and there are no other steeples to compete with it. It was built from 1652 to 1765 according to the Baroque designs of architect François Le Vau, brother of the more famous Louis, who designed several mansions nearby—as well as the Palace of Versailles. St-Louis's interior was essentially stripped during the Revolution, as were so many French churches,
but look for the odd outdoor iron clock, which dates from 1741. Check the church website for upcoming classical music events.