Bolsena, a town and comune of Italy, in the province of Viterbo in northern Lazio, 43°39N 11°59E, at 350 meters (1148 ft) above sea-level on the eastern shore of Lake Bolsena. It is 10 km (6 mi) NNW of Montefiascone and 36 km (22 mi) NW of Viterbo, and its population according to the 2001 census was 4111.

While it is fairly certain that the city is the successor to the ancient Roman town of Volsinii Novi, scholarly opinion is sharply divided as to whether Bolsena is the same as the ancient Etruscan city of Velzna (q.v.), the other candidate being Orvieto, 20 km (12 mi) NE.

Bolsena is best known for a miracle said to have occurred there in 1263, when a Bohemian priest, in doubt about the doctrine of Transubstantiation, reported bleeding from the host he had consecrated at Mass. Oddly enough, the great church eventually built to commemorate the miracle is not in Bolsena: it is the cathedral of Orvieto.