Castellazzo Bormida (Ël Castlass in Piedmontese, and Castlass an Burmia or Castlas an Burmia locally) is a comune (municipality) in the Province of Alessandria in the Italian region Piedmont, located about 70 kilometres (43 mi) southeast of Turin and about 8 kilometres (5 mi) southwest of Alessandria. As of 31 July 2007, it had a population of 4,636 and an area of 45.1 square kilometres (17.4 sq mi).