Ferentino is a town and comune in Italy, in the province of Frosinone, Lazio, 65 kilometres (40 mi) southeast of Rome. It is situated on a hill 400 metres (1,300 ft) above sea-level, in the Monti Ernici area.
Ferentinum was a town of the Hernici; it was captured from them by the Romans in 364 BC and took no part in the rising of 306 BC. The inhabitants became Roman citizens after 195 BC, and the place later became a municipium. It lay just above the Via Latina and, being a strong place, served for the detention of hostages.
From 1198 to 1557 it was the seat of the Papal rectorate of Campagna and Marittima province.
Strong in textiles (linen and embroidery) and handicraft (clay bricks from Fornaci Giorgi), after World War II Ferentino experienced a heavy industrial growth, mainly in pharmaceuticals.
Ferentino still possesses considerable remains of ancient fortifications. The lower portion of the outer walls, which probably did not stand free, is built of roughly hewn blocks of a limestone which naturally splits into horizontal layers; above this in places is walling of rectangular blocks of tuff. Two gates, the Porta Maggiore, a double gate constructed entirely of rectangular blocks of tuff, and the Porta Sanguinaria (with an arch with tuff voussoirs), are preserved. Outside this gate is the testament of Aulus Quinctilius Priscus inscribed in the rock.