It is a typical Etruscan village near Lake Bolsena. The area was among the territories of Vulci and Volsinii and was very active already from the second half of the seventh century BC. According to some scholars the Etruscan settlement of Tyro was here. Since the end of the fourth century BC it was occupied by the Romans.
The current village was born in the period of the invasion of the Lombards in the eighth century when the whole old town was razed forcing the population to take refuge on a hill. For a time the people used the caves as their dwellings and out of this peculiarity was born the name of “Castrum Criptarum”.
The area was donated to the Church by Charlemagne in 774 AD and was ruled from Orvieto. In 1119 Grotte was subjected to looting by Henry VII, and in 1186 was fortified by building a wall. Grotte then became a real castle with two access gates.
During the struggle between the feudal lords and the Holy See, the town saw a succession of different dominions and eventually came under the protection of the Apostolic Camera.
In 1537 Pope Paul III decided to create his own state, the Duchy of Castro, for his son Pier Luigi, and Grotto was in this duchy. There followed a period of peace and splendour until the relations with the Holy See, which had always been strained, broke with the murder of a bishop by the Farnese. Innocent X then sent troops and razed the town of Castro and Grotte di Castro once again came again under the control of the Apostolic Chamber in 1649.
Grotte then stayed with the Papal States until the unification of Italy.