ODERZO (Opitergium). — An ancient diocese of the patriarchate of Aquileia, today within the diocese of Ceneda, now called Vittorio Veneto. A city of Venezia Euganea, in the province of Treviso, 16 m above sea level, on the right bank of the Monticano River. The municipality has a population of 17,000 inhabitants, the capital 7,000; agriculture is highly prosperous and the production of grain and silkworm cocoons is considerable; a railway line connects it with Treviso-Portogruaro.
Of pre-Roman origin, O. was established on a slight quadrangular plateau, soon becoming an important center along the route of the Via Postumia; in 88 B.C. it became a Roman colony and subsequently a municipium belonging to the Papiria tribe; around 44 B.C. it was rebuilt by Caesar after the destruction of the Pompeians (49). A vital road junction, during the imperial period it was destroyed by the Quadi and Marcomanni (A.D. 169), and suffered serious damage as a result of the barbarian invasions. Consequently, substantial groups of inhabitants, particularly during Attila’s sack and the Lombard occupation, transferred their residence to the lagoons, giving rise to Eraclea.
Christianity penetrated relatively late, as in the other centers of « Venetia et Histria »; in all probability (the early Christian inscription of Sabiniana, Bishop Epodius, from the beginning of the fifth century), it was well organized in the second half of the fourth century, when the episcopal see was established, which, after Marcianus, continued until the seventh century.
In 667 Grimoald destroyed O. and divided its territory among Friuli, Treviso, and Ceneda. From this moment Ceneda, which was the center of a duchy, probably became an episcopal see, while O., after a period of abandonment, slowly revived and flourished again during the better years of the Venetian Republic.
Art. — The Civic Museum, housed in premises of the Town Hall, contains monuments and furnishings from the Roman period, a respectable collection of imperial-period coins, capitals, columns, and examples of funerary sculpture with fine portraits; the carpets of black-and-white mosaic floors, and especially others depicting hunting scenes (late second century A.D.), are splendid in their vitality and movement, harmonious in color with a vivid range of Impressionistic taste. Other mosaics, together with remains of a Roman house, have recently reappeared (1951) through the work of the « Associazione amici di Opitergium », an association whose purpose is to reconstruct the history and topography of the ancient city through systematic excavations. From the Renaissance period there are several arcaded, frescoed houses, which give O. a distinctive appearance, creating a picturesque and monumental area in the main square. The fifteenth-century Cathedral, recently restored, with a single nave of spacious proportions and a raised apsidal area crowned by a three-lobed structure and an elegant dome, stands on earlier early Christian and medieval buildings. Its walls are frescoed (fifteenth century), and it preserves a Roman mosaic floor with vine-scroll borders, reused in the presbytery; paintings by Palma il Giovane and Pomponio Amalteo (organ shutters), and by il Bellunello (Madonna); and bas-reliefs depicting the Virgin on a throne and in a tabernacle (Venetian art of the fourteenth century, from the school of De Sanctis, with Pisan influences).