The province is in the northeast of the Lazio region. It borders to the west, along the Tiber river, with the Viterbo province and the Rome, to the north with the Umbria region (provinces of Perugia and Terni), and to the east by Province of Ascoli Piceno in the Marche region, and with the provinces of L'Aquila and Teramo in the Abruzzo region.