Corseul (French pronunciation: [kɔʁsœl]; Breton: Kersaout; Gallo: Corsoeut) is a commune in the Côtes-d'Armor department of Brittany in northwestern France.

[3] Corseul was called Fanum Martis ("Temple of Mars") in Latin and was the capital of the Gallo-Roman province of Coriosolites.

[4] In the 3rd and 4th centuries, like many other cities, Fanum Martis was renamed for its people, the Curiosolitae.

This name change occurred as the Roman Empire weakened and paralleled a revival of the ancient Gallic gods in local religious sculptures and dedicatory inscriptions.

[5] Some 1.5 kilometres to the southeast, at Haut-Bécherel, stand the prominent remains of an extensive Roman temple sanctuary, built at the time of Nero and Vespasian.