a town of Campania, Italy, in the province of Caserta, 6 m. by road N.W. of Formia. Pop. (1901) 5797. The town is picturesquely situated 690 ft. above sea-level, in the mountains which the Via Appia traverses between Fondi and Formia.
Interesting remains of the substruction wall supporting the ancient road are preserved in Itri itself; and there are many remains of ancient buildings near it. The brigand Fra Diavolo, the hero of Auber's opera, was a native of Itri, and the place was once noted for brigandage.