Valeggio is a commune in the Province of Pavia, region of Lombardy, Italy, located about 40 km southwest of Milan and about 25 km west of Pavia. Valeggio borders the following municipalities: Alagna, Dorno, Ferrera Erbognone, Ottobiano, Scaldasole, Tromello. In medieval times, it was a fief of the monastery of San Salvatore at Pavia. Later it was under several noble families from the area, until it became part of the Duchy of Savoy in 1713.