CARSIOLI (mod. Carsoli), an ancient city of Italy, on the Via Valeria, 42 m. E. by N. of Rome. It was founded in the country of the Aequi between 302 and 298 B.C., just after the establishment of Alba Fucens, no doubt as a stronghold to guard the road to the latter. It is mentioned in 211 B.C. as one of the twelve out of thirty Latin colonies which protested their inability to furnish more men or money for the war against Hannibal. We find it used in 168 B.C. like Alba Fucens as a place of confinement for political prisoners. It was sacked in the Social War, but probably became a municipium after it, though we hear but little of it. The modern town of Carsoli first appears in a diploma of A.D. 866, but the old site does not seem to have been abandoned until the 13th century. It is now occupied only by vineyards, and lies about 2100 ft. above sea-level, in a plain surrounded by mountains, now called Piano del Cavaliere. The line of the city walls (originally in tufa, and reconstructed in limestone), built of rectangular blocks, can be traced, and so can the scanty remains of several buildings, including the podium or base, of a temple, and also the ancient branch road from the Via Valeria (which itself keeps just south-east of Carsioli), traversing the site from north to south. The forty-third milestone of the Via Valeria still lies at or near its original site; it was set up by Nerva in A.D. 97. One mile to the north-west of Carsioli are the remains of an ancient aqueduct consisting of a buttressed wall of concrete crossing a valley.
See G. J. Pfeiffer and T. Ashby in Supplementary Papers of the American School in Rome, i. (1905), 108 seq. (T. As.)