BISENZIO. - An ancient episcopal see of Lazio on the western shore of Lake Bolsena. An inscription from 254 recalls the "Senatus populusque Visentinus" (CIL, XI, 2014). In the passage from the Dialogues of St Gregory (III, 17), which mentions a "Quadragesimus baxentinae" or "buxentinae ecclesiae subdiaconus", L. Duchesne saw the first mention of the diocese of B., contrary to the opinion of those who referred it to Busento in Lucania. Since it is said in the aforementioned passage that Quadragesimus used to pasture his flock "in Aureliae partibus", it was right to seek the "ecclesia baxentina" or "buxentina" in Tuscia, as F. Ughelli did, though he read "Bulcentinae" or "Bolciensis ecclesiae" due to the proximity of Vulci to the Via Aurelia. The expression "in Aureliae partibus" should be interpreted broadly; thus B., not far from Valentano and the ruins of Castro, can be considered "in Aureliae partibus". During the Lombard invasion, the bishop of B. would have taken refuge in Castro (q.v.), retaining the official title that reappears in 743 as "Bisuntianus episcopus".