The cathedral was built in the 12th century. by Jean de Chatillon on an islet easier to defend than the City of Aleth, where was the ancient cathedral Saint-Pierre.
The building has considerably changed since the last war: a new spire and a rosette at the back of the choir, illuminated by a stained glass window by Jean Le Moal.
Very beautiful conciliar furniture of Arcabas.
In the chapels of the choir, tombs of Jacques Cartier and Duguay-Trouin.