The Roman Catholic Diocese of Rennes is a significant ecclesiastical territory in France, located in the region of Brittany. Established in the 3rd century, it serves the spiritual needs of the Catholic community in the city of Rennes and surrounding areas. The diocese is part of the larger Archdiocese of Rennes, which oversees several other dioceses in the region. The diocese is known for its rich history and cultural heritage, including numerous churches and religious sites. The Cathedral of Saint Peter in Rennes serves as the seat of the bishop and is a prominent landmark. The diocese also engages in various social and educational initiatives to support its parishioners.