TORTONA (anc. Dertona)  , a town and episcopal see of Piedmont, Italy, in the province of Alessandria, from which it is 14 M . E. by rail, on the right bank of the Scrivia, at the northern foot of the Apennines, 394 ft. above sea-level . Pop . (19or), 11,308 (town); 17,419 (commune) . Tortona is on the main line from Milan to Genoa; from it a main line runs to Alessandria, a branch to Castelnuovo Scrivia, and a steam tramway to Sale . Its fortifications were destroyed by the French after Marengo (1799); the ramparts are now turned into shady promenades . The cathedral, erected by Philip II., contains a remarkably fine Roman sarcophagus of the Christian period . Silk-weaving, tanning and hat-making are the chief industries; and there is some trade in wine and grain . Dertona, which may have become a Roman colony as early as the 2nd century B.C. and-certainly did so under Augustus, is spoken of by Strabo as one of the most important towns of Liguria . It stood at the point of divergence of the Via Postumia (see LIGURIA) and the Via Aemilia, while a branch road ran hence to Pollentia . A number of ancient inscriptions and other objects have been found here . In the middle ages Tortona was zealously attached to the Guelphs, on which account it was twice laid waste by Frederick Barbarossa, in 1155 and 1163 .

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