Casalpusterlengo is a comune in the Province of Lodi in the Italian region Lombardy, located about 50 kilometres southeast of Milan and about 20 kilometres southeast of Lodi. It received the honorary title of city with a presidential decree on October 30, 1975. The town has a Baroque church of Santi Bartolomeo e Martino, which was built in the 14th century but refurbished between 1602 and 1610. The town also has a communal palace and a tower from the medieval castle.