BOLSENA (anc. V olsinii)i, province of Viterbo, Italy, 1 2M. W.S.W. of Orvieto by road, on north-east bank of Lake Bolsena. Pop. of the commune (1931) 3,825. The town is dominated by a picturesque mediaeval castle. The th century church of S. Christina (martyred in 278 by drowning in the lake according to the legend) has a fine Renaissance facade, constructed about 1490 by Cardinal Giovanni de'Medici (afterwards Pope Leo X.), and some good terra cottas by the Della Robbia; in catacombs be neath is the tomb of the saint. A Bohemian priest, sceptical of the doctrine of transubstantiation, was convinced by the appear ance of drops of blood on the host he was consecrating on an altar of the crypt (1263). In commemoration of this Pope Urban IV. instituted the festival of Corpus Christi, and ordered the erection of the cathedral of Orvieto.
Lake Bolsena (anc. Lacus V olsiniensis), ,000ft. above sea level, 7i sq.m. in area, and 48oft. deep, is almost circular, and was the centre of a large volcanic district, though probably not itself an extinct crater. Its sides show fine basaltic formation. It contains two islands, Bisentina and Martana, the latter con taining remains of the castle where Amalasuntha, daughter of Theodoric, was strangled.