Acerrae was a city of Cisalpine Gaul, in the territory of the Insubres. Polybius describes it merely as situated between the Alps and the Po; and his words are copied by Stephanus of Byzantium: but Strabo tells us that it was near Cremona: and the Tabula places it on the road from that city to Laus Pompeia, at a distance of 22 Roman miles from the latter place, and 13 from Cremona. These distances coincide with the position of Gherra or Gera, a village, or rather suburb of Pizzighettone, on the right bank of the river Adda. It appears to have been a place of considerable strength and importance even before the Roman conquest: and in 222 BC, held out for a considerable time against the consuls Marcellus and Scipio, but was compelled to surrender after the Battle of Clastidium.