Mostaganem (Berber languages: Mustɣanem; Arabic: مستغانم‎) is a port city in and capital of Mostaganem province, in the northwest of Algeria. The city, founded in the 11th century lies on the Gulf of Arzew, Mediterranean Sea and is 72 km ENE of Oran. It is considered as the second largest city in the NW after Oran and as Algeria’s 4th largest port city with its 457.986 inhabitants as of the 2018 census.

The city was founded in the 11th century as Murustage but has origins going back to Punic and Roman times. In 1516 it was captured by the Ottoman admiral Barbarossa and became a centre for Mediterranean sea corsairs, as well as a commercial port. By 1700 it had come under Ottoman rule and in 1833 the city was taken by France and a garrison established. Algeria became independent in 1962.