Bolsena is a town and comune located in the province of Viterbo in northern Lazio, Italy. It is situated on the eastern shore of Lake Bolsena, positioned approximately 10 km north-northwest of Montefiascone and 36 km northwest of Viterbo. The ancient Via Cassia, which currently serves as the highway SR143, follows the lakeshore for a portion of its route and passes through the town.
The city is notably recognized as "the city of the Eucharistic miracle." This designation stems from an event associated with the solemnity of Corpus Domini, to which the celebration was extended to the entire Catholic Church.