RIEZ. – An ancient diocese in the department of Basses-Alpes, France. A Ligurian city, it later became the capital of the Reii, hence the name “Regium,” from which the present name derives. It was a colony under Latin law in the time of Augustus. The first known bishop was Prospero, predecessor of St. Massimo (434–60); he was succeeded by Fausto (462–95), formerly abbot of Lerins.
R. was sacked by the Saxons in 572; the inhabitants and the bishop abandoned the city, which subsequently also suffered during the Saracen incursions from 793 to 875. Shortly afterward, Bishop Edolo transferred the see to the hill, to the chapel of S. Massimo, where the inhabitants also moved. Among its prelates were Cardinals Pietro Després in 1318 and Guido Bentivoglio. The diocese, a suffragan of Aix, was suppressed in 1790; in 1801 its territory was united to the see of Digne, whose bishop has also borne the title of R. since 1916. Bishop Augier (1096–1130) had the Cathedral and Baptistery rebuilt; the former, Notre-Dame-de-la-Sède, fell into ruin in the fifteenth century; near the present church, several Gothic bays remain. The Baptistery was of the Provençal and Ligurian type: a quadrangular building externally, surmounted by an octagonal tower that collapsed during the Saracen incursions. The interior is an octagon measuring 9.25 by 8.40 m., with four small apses and a circular ambulatory; eight Roman columns of Var granite support the dome. The floor was subsequently raised, and the bases of the columns are partly interrupted. The Baptistery was abandoned at the end of the sixteenth century, and the inhabitants called it the Pantheon; ceded to the Confraternity of Tailors, it was consecrated to their patron, s. Chiaro; it then passed to the White Penitents; at present it has been converted into an archaeological museum. On S. Massimo hill, the chapel, rebuilt in 1857, preserves a Romanesque apse with an ambulatory supported by six Corinthian columns.
From Peiresc’s papers it appears that the pavement mosaic of the cathedral of R. depicted Constantine on horseback passing over the body of a vanquished man; the scene was accompanied by the distich: Rex Constantinus, leprosus, virque benignus, est factus sanus, sacro baptismate tactus. This recalled the legend of the Emperor cleansed of leprosy through Baptism (R. Movat, Mosaïque de R. offrant l'image de Constantin, in Bull. de la Soc. des antiquaires de France, 1885, pp. 68–71).