The Cathedral of Saint-Louis is a modest colonial church at the centre of the island, built on the site of an earlier chapel that dates to the earliest French settlement. It is the seat of the Diocese of Saint-Louis du Sénégal and has been active since the early 19th century. The exterior is plain compared to what you might expect of a cathedral — the budget and the climate conspired against anything elaborate — but the interior is cool and peaceful, with coloured light filtering through the windows.
The church sits in a small square that forms a natural gathering point in the afternoon. It is not a major sight in itself but is very much part of the fabric of the island, and worth a quick look while walking the colonial grid. Sunday mass draws a congregation that is a mix of locals and expats, a reminder that Saint-Louis has had a Christian community since the city's founding.