VELLETRI, a town of Italy, in the province of Rome, and 26 miles by rail to the south-east of that city, is picturesquely situated on a spur of Monte Artemisio on the southern edge of the Alban Hills and overlooking the Pontine marshes. The streets are steep, narrow, and irregular. In the highest part of the town are the municipal offices, with an important ancient inscription relating to the restoration of the amphitheatre under Valentinian and Valens. Velletri is the seat of the bishop of Ostia; the cathedral (1660) contains some good sculpture of the school of Sansovino. The neighbourhood produces a celebrated wine, a chief source of wealth to the town. The population in 1881 numbered 13,532.

At the close of the Latin War (336 b.c.) the Volscian Velitrae had its walls razed to the ground and its leading inhabitants banished beyond the Tiber, their lands being given to Roman settlers. It became a flourishing municipium, and was the native place of the Octavian family. In the neighbourhood of Velletri Don Carlos, younger son of Philip V. of Spain, in 1734 gained over the Austrians a decisive victory, which ultimately secured him as Charles III. the kingdom of the Two Sicilies.