Dol-de-Bretagne Cathedral () is a Roman Catholic church located in Dol-de-Bretagne. The cathedral is dedicated to Saint Samson, one of the founding saints of Brittany. It was formerly the seat of the Archbishop of Dol, one of the nine ancient bishoprics of Brittany. The cathedral suffered badly from the excesses of the French Revolution, becoming successively a "Temple de la Raison", then a stable, then a warehouse. Revolutionaries caused considerable damage and many treasures were lost. When it eventually returned to being a house of worship, its role as a bishopric was abolished by the Concordat of 1801 when the Dol diocese was merged into the Dioceses of Rennes and Saint-Malo. The Concordat of 1801 was an agreement between Napoleon and Pope Pius VII, signed on 15 July 1801 in Paris, which sought national reconciliation between revolutionaries and Catholics. The Concordat was abrogated by the law of 1905 on the separation of church and state.