Piacenza (pyächānˈtsä) [key], city (1991 pop. 102,268), capital of Piacenza prov., in Emilia-Romagna, on the Po River. It is an agricultural, commercial, and industrial center. Manufactures include agricultural machinery, chemicals, furniture, buttons, and food products. The city was a Roman stronghold (called Colonia Placentia) against the Gauls and was later occupied by the Goths, the Lombards, and the Franks. A free commune by the 12th cent., Piacenza joined the Lombard League. In 1545 it formed, with Parma and its territory, the duchy of Parma and Piacenza, ruled, until 1731, by the Farnese family. Noteworthy buildings include the Lombard-Gothic Palazzo del Comune (1281); the cathedral (1122–1233), with frescoes by Guercino; and the churches of San Savino (12th cent.) and Madonna di Campagna (16th cent.).