In 1646 work started on the twin-towered Church of St Sulpicius, lined inside with 21 side chapels, and it took six architects 150 years to finish. It's famed for its striking Italianate façade with two rows of superimposed columns, its Counter-Reformation-influenced neoclassical decor and its frescoes by Eugène Delacroix – and its setting for a murderous scene in Dan Brown’s The Da Vinci Code.
You can hear the monumental, 1781-built organ during 10.30am Mass on Sunday or the occasional Sunday-afternoon concert.
The frescoes in the Chapelle des Sts-Anges (Chapel of the Holy Angels), first to the right as you enter the chapel, depict Jacob wrestling with the angel (to the left) and Michael the Archangel doing battle with Satan (to the right), and were painted by Delacroix between 1855 and 1861. Free guided tours of the church depart in English on the 1st Sunday of each month at 12.30pm. To delve into the crypt, sign up in advance for a tour (in French) on the 2nd and 4th Sundays of the month at 2pm.