A key city in the region, it was destroyed by barbarians but the town was rebuilt under the rule of bishops in the 10th century.

By the 12th century, the city was a free comune and it later fought against Frederick I, Holy Roman Emperor as part of the Lombard League.

In the Renaissance period it passed from French, to papal, to Viscontis, to Sforzas rule.

[6] The northernmost part of the province is largely flat but the southernmost two thirds are hilly and extend to the Ligurian Apennine Mountains; the highest point in the province is the peak of Monte Bue which is 1,777 metres (5,830 ft) above sea level.

The alluvial Po Plain is agricultural land and there are many vineyards growing grapes from which the eighteen wines of the region are made.