Gradoli is a comune (municipality) in the Province of Viterbo in the Italian region Latium, located about 100 kilometres (62 mi) northwest of Rome and about 35 kilometres (22 mi) northwest of Viterbo.

Gradoli sits on a tuff hill in the Monti Volsini area, a few kilometers from the Lake Bolsena. It is home to a palace which was owned by the Farnese family; it was commissioned by Pope Paul III to (allegedly) Antonio da Sangallo the Younger on the site of the medieval castle. Of the castle, only few traces remains, including a defensive tower, the entrance arch and few parts of the walls; its ditch has been now transformed into roads and squares. Sangallo also designed the nearby church of Santa Maria Maddalena.