The Cathedral of Saint Vincent de Paul stands at the top of Avenue Bourguiba, its twin 60-metre towers framing the end of the boulevard's long axis. Built in a neo-Romanesque style with some Gothic elements, it is a prominent piece of French colonial urbanism — designed to announce the presence of European civilization at the symbolic heart of the city.
The interior is quieter and more contemplative than the busy avenue outside, with high vaulted ceilings, stained glass, and the particular cool of a large stone building on a hot day. Non-Catholic visitors are welcome outside of services. The building is more interesting architecturally than spiritually, but it's worth stepping inside — and the contrast between the Catholic cathedral and the medina's ancient mosque just five minutes' walk away captures the city's layered character precisely.