CASILINUM (mod. Capua), an ancient city of Campania, Italy, 3 m. N.W. of the ancient Capua. Its position at the point of junction of the Via Appia and Via Latina, and at their crossing of the river Volturnus by a three-arched bridge, which still exists, gave it considerable importance under the Roman republic; and while the original pre-Roman town, which was doubtless dependent on the neighbouring Capua, stood entirely on the left (S.) bank, surrounded on three sides by the river, the Roman city extended to the right bank also; remains of it have been found at some 25 ft. below the modern ground-level, the river-bed having risen considerably. In the Second Punic War it was occupied by Fabius Cunctator in 217 B.C., taken by Hannibal after a gallant defence by troops from Praeneste and Perusia in the winter of 216–215, but recaptured in the following year, serving the Romans as their base of operations against Capua. It lost its independence and became a praefectura. Caesar conducted a colony thither in 59 B.C., which was renewed by Antony in 44 B.C. The veterans took Octavian’s side after Caesar’s death, but it seems to have been united with Capua before the time of Vespasian, and it does not occur in the list of independent communities given by Pliny, who indeed (Hist. Nat. iii. 70) speaks of the morientis Casilini reliquiae, and only its position at the junction of the roads redeemed it from utter insignificance. (T. As.)