Saint-Malo Cathedral (Cathédrale Saint-Vincent-de-Saragosse) is the oldest building in the Intra-Muros, with a nave dating from the 12th century. It survived the 1944 bombardment less intact than the surrounding streets — the original medieval spire was destroyed, though the 1971 replacement matches it reasonably well. The interior shows the stages of construction clearly: Romanesque arches in the nave, Gothic vaulting toward the choir, and modern stained glass replacing the windows destroyed in the war.
The cathedral is easy to find from the Grande Porte, the main gate of the old town. It is where Cartier and his crew heard Mass before setting sail for Canada in 1534, and a plaque inside commemorates this. The grave of the explorer is in the crypt.