It has an area of 5,170 sq km and a population of 254,479, of whom 253,500 are Catholic. The diocese is divided into 6 archpriestships and 27 deaneries with 297 parishes served by 538 diocesan priests and 76 regular clergy; it has a major and minor seminary; 4 male and 138 female religious communities (Ann. Pont., 1951, pp. 241-42).
The city of L., situated on both banks of the Mayenne, is of feudal origin (Vallum Guidonis). From the 13th century until the French Revolution it passed under the lordship of various noble families. It was occupied by the English in 1428, but abandoned the following year. The diocese was created by Pius IX by a bull dated 30 June 1855, carved out of the diocese of Le Mans; the church of the Trinity was elevated to cathedral status. The first bishop elected of L. was Mgr E. Bougaud (v.), who died after only eight months. It is a suffragan of Tours. The church of the Trinity preserves the central tower and the southern portal from the late 12th century, while the choir and the northern portal are Renaissance. It contains the funerary monument of the bishop of Rennes, G. Ouvrain (1347). The church of St Venerandus (1495-1563) has notable 16th-century stained glass; the church of Notre-Dame-des-Cordeliers was built between the 14th and 16th centuries.
In the diocese are well-known shrines such as those of Notre-Dame-de-Prix in L., Notre-Dame-de-l’Empire at Evron, Notre-Dame-des-Freux at Bellebranche, Notre-Dame-d’Avières and Notre-Dame-de-Courlefosse at Fougerolles, and other places of pilgrimage for centuries.