ARIANO, diocese of. - In the Irpinian region, province of Avellino, suffragan of Benevento, it has 24 parishes, 44 diocesan priests, and 9 regular clergy. Area of the diocese: 463 sq. km; population: 62,000 inhabitants, almost all Catholics, of whom approximately 21,000 reside in the municipality of A. Patron: St. Ottone.
A centre of the Irpini, it merged with a Roman stopping-place on the Via Appia Traiana, whence the name Ara Iani. It became contested under the Lombards, was then conquered by the Normans, and was made the seat of a parliament by Ruggero II (1140). In the thirteenth century it was granted as a fief by Carlo d'Angiò to the Vaudemont; in the fifteenth century it passed to Attendolo Sforza and later to the Carafa. Severely damaged by earthquakes and eruptions of Vesuvius (1546, 1781, 1930), it always rose again. The tradition that makes St. Pietro its evangelizer is legendary. There are no traces of the establishment of the bishopric before the tenth century; at the Roman Council of 969, Giovanni XIII subjected several dioceses of the region, among them A., to the archbishopric of Benevento. The first bishop of whom certain information exists was Meinardo of Poitiers (1070). The Cathedral was erected by Bishop Nicola degli Ippoliti, completed and consecrated by Bishop Diomede Carafa in 1512; the seminary was founded in 1564.