TUSCANIA, Diocese of. - In Lazio, in the province of Viterbo, united with the diocese of Viterbo (v., also for the statistical data). T. rises on the slope of a tufa hill; of Etruscan origin, it later became a Roman municipium and, when the Papal State was constituted, it was of notable importance until the 13th century. Around 1130 it took the name of Toscanella, which it kept until 1911.
The preaching of the Gospel at T. must have occurred after the Constantinian peace, even though the names of martyrs venerated there might give the opposite impression. A Passio (BHL, 7550), composed in Rome, very probably between the 5th and 6th centuries, commemorates Verianus, Marcellinus and Secundianus as buried in St. Peter's of T. and calls all three of them Romans. Other martyrs, also venerated at T., have an obscure history, such as Tesidius (1 April), Potens (7 Dec.), Justina (23 Dec.). The oldest Christian inscription found in the church of St. Peter dates back to 407 (CIL, XI, 1, 2994-95). The first in the series of known bishops is Virbonus, in 595. In the 11th century, the bishoprics of Civitavecchia and of Bieda seem to have been subject to the episcopal see of T. In 1192 Celestine III erected the episcopal see of Viterbo (v.) and united T., Civitavecchia and Bieda to it, so that from then on the bishops were called bishops of Viterbo and T.: this must have happened between August and October of the aforesaid year, because still in August Cardinal Giovanni of St. Clement subscribed himself as bishop of T., whereas on 4 October he subscribed himself as bishop of Viterbo and T. It cannot be denied that with the erection of the see of Viterbo, T. passed into second place, especially because of the importance that the city of Viterbo came to assume, where the bishops gradually established their permanent residence. The oldest documents preserved in the archives of T. bear the dates 1086 and 1097.
Among the ancient monasteries of the Tuscanian territory, of which only the ruins remain today, mention should be made of the Benedictine one of St. Justus, very close to T., which in the 12th century passed to the Cistercians; that of St. Savinus, over which in the 10th century the jurisdiction of the abbey of Cluny extended; that of St. Stephen of the island of Martana in Lake Bolsena, already known from a privilege of Leo IV to bishop Virbonus of T., between 847 and 855. On the other hand, St. Mary Major and St. Peter are preserved and are considered the most beautiful Romanesque churches of Lazio, near the carriage road, on the edges of the built-up area of T. St. Mary Major was also the first cathedral of T., which was later transferred to St. Peter, and in 1572 to the church of St. James. The two aforesaid churches show their architectural development from the 8th to the 13th century, but they must have replaced pre-existing buildings of worship.
T. is immediately subject to the Holy See and has its court of appeal at the vicariate of Rome. - See plate XLIV.