The Quadrilatero () is the traditional name of a defensive system of the Austrian Empire in the Lombardy-Venetia, which connected the fortresses of Peschiera, Mantua, Legnago and Verona between the Mincio, the Po and Adige Rivers. In the period between the end of the Napoleonic Wars and the Revolutions of 1848, they were the only fully modernized and armed fortresses within the Empire. Starting from c. 1850, supplies and reinforcements were shipped to the positions through the new Venice-Milan railroad.