The origin of the Diocese of Le Mans has given rise to discussions concerning the value of the Gesta domni Aldrici, and of the Actus Pontificum Cenomannis in urbe degentium.

It names several parishes recently created in the ninth century among thirty four allegedly founded by St Julianus, one of the Seventy disciples.

Christians were not a legal cult until the time of Constantine I (d. 337), and a diocese could neither own property as a collective entity nor build public places of worship.

[9] Even the textual evidence, such as it is, shows that there was no work of any importance on the cathedral from 557 to 832, the beginning of the reign of Bishop Aldric, though it was interrupted by his flight from his diocese.

[17] The church of Notre-Dame de la Couture (originally dedicated to S. Peter[18]) dates from the thirteenth, fourteenth, and fifteenth centuries, traces of earlier buildings having disappeared completely.

[19] The Abbey of Solesmes, founded by Geoffroy de Sablé in 993 and completed in 1095,[20] has a thirteenth-century which is a veritable museum of sculptures of the end of the fifteenth and sixteenth centuries.

Its "Entombment of Christ," in terracotta, is famous; the Mary Magdalen in the group, already celebrated even in the fifteenth century for its beauty attracted the attention of Richelieu, who thought of having it brought to Paris.

The Dominican convent of Le Mans, begun (according to local myth) about 1219 and, according to the claim, during the lifetime of St. Dominic, was able to begin its construction thanks to the benefactions of one 'John of Troezen', Count of Maine,[54] an English nobleman.

The house was far less wealthy when the theologian Nicolas Coeffeteau, who died in 1623, began his career as a Dominican by taking his vows at Le Mans in 1588, and who later became Bishop of Marseille.

The diocese honours in a special manner as saints: Peregrinus, Marcoratus, and Viventianus, martyrs; Hilary of Oizé, nephew of St. Hilary of Poitiers (in the fifth century); Bommer, Almirus, Leonard, and Ulphace, hermits; Gault, Front, and Brice, solitaries and previously monks of Micy; Fraimbault, hermit, founder of a small monastery in the valley of Gabrone; Calais, hermit and founder of the monastery of Anisole, from whom the town of Saint-Calais took its name; Laumer, successor to St. Calais; Guingalois or Guénolé, founder of the monastery of Landevenec in Brittany, whose relics are venerated at Château du Loir.

All in the sixth century: Rigomer, monk at Souligné, and Ténestine, his penitent, both of whom were acquitted before Childebert, through the miracle of Palaiseau, of accusations made against them (d. about 560); Longis, solitary, and Onofletta, his penitent; Siviard, Abbot of Anisole and author of the life of St. Calais (d. 681); the Irish St. Cérota, and her mistress Osmana, daughter of a king of Ireland, died a solitary near St-Brieuc, in the seventh century; Ménélé, and Savinian (d. about 720), natives of Précigné, who repaired to Auvergne to found the Abbey of Menat, on the ruins of the hermitage where St. Calais had formerly lived.

The famous founder of the Trappists, Abbot de Rancé, made his novitiate at the Cistercian Perseigne Abbey in the Diocese of Le Mans, though his subsequent career was entirely elsewhere: his uncle was Archbishop of Tours, where he was appointed Archdeacon.

Also there may be mentioned as natives of the diocese, Urbain Grandier, the notorious curé of Loudun, who was tortured and burned to death for sorcery in 1634; and Mersenne, the Minim (d. 1648), philosopher and mathematician and friend of Descartes and Pascal.

The remaining portion was conveyed to the interior of the citadel and placed in the apse of the collegiate church of St. Pierre la Cour, which served the counts of Maine as a domestic chapel.