To the west it is bounded by the Province of Alessandria (Piedmont) and to the east by the Province of Piacenza (Emilia-Romagna). The territory comprises a plain close to the Po, a hilly section, which rises from the Valle Staffora to the west and from the upper Val Tidone to the east, and a mountainous zone which in addition to Monte Lesima includes the peaks of Monte Chiappo (1700 m) Cima Colletta (1494 m) and Monte Penice (1460 m). The main watercourse is the Staffora; other streams include the Ardivestra, the Versa and the upper part of the Tidone, including part of the Lago di Trebecco reservoir.