Saint-Dizier (săN-dēzyāˈ) [key], town (1990 pop. 35,558), Haute-Marne dept., NE France, on the Marne River. It is a trading and transportation center; its manufactures include machinery, musical instruments, and metals. Saint-Dizier has many structures dating from the 13th to the 18th cent. There is also a museum with Roman, Carthaginian, and early Christian artifacts.