NEPI AND SUTRI, Diocese of. - In Lazio, in the province of Viterbo, immediately subject to the Holy See. They have an area of 782 sq km with a population of 63,854 inhabitants, divided into 35 parishes, with 61 secular priests and 46 regulars, 14 male religious communities and 35 female. They have the major seminary in common with the other dioceses of upper Lazio, at La Quercia near Viterbo.
N. is the Nepete or Nepet of the Etruscans; it was conquered by the Romans in 383 B.C. and became the bulwark against Mount Cimino. Christianity entered N. in the pre-Constantinian age. A Passio, not much earlier than the 11th century, places on 24 August a Ptolemy, bishop of the Pentapolis and Tuscia, and a Romanus, bishop of N., his disciple, under Claudius. This is probably Claudius II (268-70), since the hagiographers of Tuscia Suburbicaria had the custom of placing their martyrs under this Emperor. But, in time, it was wished to go back to Claudius I (41-54), that is, to the first half of the 1st century, and Ptolemy and Romanus were spoken of as two protomartyrs of the West. These, according to the Passio, would have been beheaded in civitate Pentapolis and buried a little way off, in the small estate of the matron Savinilla. The civitas Pentapolis would have to be identified with N. Nevertheless, the two supposed martyrs of Nepi are unknown to all the ancient martyrological sources (cf. BHL 6984-87): Ptolemy and Romanus occur among the names of the Roman martyrs.
On the road, coming from Rome, before reaching N., in 1540 an ancient Christian cemetery was found, beneath the church of St. Ptolemy, which was called the "catacomb of Salvinilla". In his time M. A. Boldetti could still count 560 loculi there; G. B. De Rossi judged it to be of the end of the 3rd or the beginning of the 4th century. F. Ughelli and P. Gama, after Romanus, place Milionus, Claudius II and Eulalius in the series of the bishops of N. without adducing proofs. The name of the most ancient bishop known today is that of "Proiectitus" who subscribed the acts of the Roman Synod of 465. N., with the cathedral of St. Mary, remained autonomous until 12 December 1435, when Eugene IV, because of the misery to which the episcopal mensa had been reduced, united it to the diocese of S. (v.). From then on the bishop was called of S. and N. or of N. and S., with annual alternating residence. The most famous in the series of the two united dioceses is the Dominican Michele Ghisleri, later pope, St. Pius V (v.).
In the territory of the diocese of N. were the ancient monasteries of St. Blaise, of St. Benedict and of St. Elias. The last two in the Valle Suppentonia, not far from Castel S. Elia (v.), to which the last one gave its name. Gregory the Great (Dial., 1, 7, 8) recalls the abbot Anastasius of the monastery of the Valle Suppentonia, who in all probability must be identified with one of the aforesaid. Of the monastery of St. Elias the medieval Basilica is preserved with its very well-known frescoes and a unique collection of vestments, recently arranged in a hall adjoining the parish church. The pontifical Sanctuary of the Madonna ad rupes, kept by the Friars Minor of the province of the Holy Cross in Saxony, which owes its arrangement to Fr. Bernhard Döbing, who died bishop of N. and S. in 1917, is situated on the cliff and originates from one of the grottoes that in the 6th century housed a laura of monks.