BIEDA. – An ancient episcopal city of Lazio, in the province of Viterbo, built on a tuff plateau at the confluence of the Biedano stream and the Rio Canale; it is traversed by the Via Clodia and is not far from the Via Cassia. The Romans called it Blera or Bleva, and under their rule it maintained the prosperity it had acquired during its Etruscan civilization, as the discovery of the necropolis, inscriptions, and other monumental remains has testified. Its decline must have occurred in the early Middle Ages, doubtless due to the proximity of other cities more accessible because of their topographical position. In the first half of the 8th century, B. was the property of the Holy See; it was occupied in 739 by the Lombards, but soon restored by King Liutprand to Pope Zachary; in 772 Desiderius reconquered it, until, two years later, with the destruction of the Lombard kingdom in Italy, it definitively became part of the Patrimony of St. Peter.
The origin of Christianity in B. is linked to the name of St. Sensius, whose Life (BHL 7581-82b), written between the 7th and 8th centuries by monks, probably of the Tuscan archipelago, presents him as a missionary monk of B., who died at the end of the 5th century after overcoming the pagan resistance of its citizens. His name appears in the Martyrologium Hieronymianum on May 25, and De Rossi suspects that St. Sensius may be earlier than the mid-5th century. Lanzoni, in turn, considers him a martyr of the persecutions, whom the anonymous author of the Life, during the golden age of monasticism in Tuscany, celebrated as a 5th-century monk.
The origin of Christianity in B. thus depends chronologically on the time when St. Sensius is believed to have lived, who may be considered the evangelizer of the Biedan territory. The first bishop of B. known to us is Maximianus, who appears among the signatories of the Roman synods from 487 to 502. B. was the birthplace of Pope Sabinianus (Liber Pontificalis, ed. L. Duchesne, I, p. 315); St. Gregory the Great mentions (Register, IX; Ep. 96 in MGH, Epist., II, p. 106) in its territory an abbey of which, however, no trace remains; while a church in honor of St. Sensius must soon have arisen in B., which Leo IV had decorated in the 9th century (Liber Pontificalis, loc. cit., II, p. 125). In 1093 the bishop Riccardo still bore the title of B., but had already united that of Tuscanìa (v.). In 1192 Celestine III, establishing the bishopric of Viterbo, annexed to it the ancient dioceses of Tuscanìa, Civitavecchia, and B., ordaining that the incumbent of the new see should bear the title of Bishop of Viterbo and Tuscanìa.