ARRETIUM (mod. AREZZO), ancient city, Etruria, upper valley of Arno, on the Via Cassia, 5om. S.E. of Florentia. The hill top, enclosed by a wall, was the site of the ancient city and the mediaeval citadel, as so often in Italy. Etruscan tombs have been found in the lower part of the modern town, which appears to be on the Roman site. Vitruvius and Pliny speak of the strength of its walls of bricks, and remains have been found be longing, at the earliest, to the 4th century B.c., and probably de stroyed by Sulla in Si B.C. The bricks measured I Z by I Roman foot and foot thick. Many Roman buildings have been found, and the amphitheatre is still visible in the south angle. Arretium aided the Tarquins after their expulsion. It opposed Rome at the end of the 4th and beginning of the 3rd century B.C., but soon sought for help against the Gauls, against whom it was almost a frontier fortress. It was an important Roman base during the Hannibalic Wars, and in 205 B.C. furnished Scipio with quantities of arms and provisions. In 187 B.C. the high road was extended as far as Bononia. Arretium took the part of Marius against Sulla, and the latter settled some of his veterans there as colonists. A considerable contingent from Arretium joined Catiline, and in 49 B.C. Caesar occupied it. C. Maecenas was perhaps a native of Arretium. Its fertility was famous in ancient times, and still more famous was its red pottery (see CERAMICS). The museum contains a fine collection of vases and of their moulds and of mediaeval majolica. (See Studi Etruschi, I. [1927],