ARIANO, a town of Italy, in the province of Avellino, about 38 miles N.E. of Naples, situated 2500 feet above the level of the sea, on a steep and rocky hill, between the rivers Calore and Tribaldo. Founded by the Greek governors of Apulia, it continued to be an important military post for several centuries, and was frequently taken and retaken during the various dynastic struggles of southern Italy. A parliament was held here by Roger I. in 1140, nod in 164S the town was pillaged by the duke of Guise. It is still a bishop's see, and the chief town of a circondario, with a cathedral, and a large number of churches. Earthenware is manufactured, and there is some trade in wine and butter. The most peculiar feature of the town is the multitude of troglodytic dwellings, in which the poorer classes reside. The district is highly volcanic, and the town has suffered severelyfrom earthquakes (1456,1732), and only 7 miles distant is the lake of Amsanctus (Mofete), remarkable for its suffocating exhalations. Population, 14,347. (See Vitate, Storia della Citta d' Ariano, Rome, 1794.)