Castiglione in Teverina is a comune, or municipality, situated in the Province of Viterbo within the Lazio region of central Italy. It is located approximately 90 kilometres northwest of Rome and about 25 kilometres northeast of the provincial capital, Viterbo.
The town serves as a local administrative center in the rural landscape of the province. Its geographic positioning places it within the historical territory of the Lazio region, characterized by its proximity to major regional hubs like Rome and Viterbo.