Mostaganem 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 country's northwest, after Oran, and as Algeria's fourth-largest port city with its 406.190 inhabitants as of the 2019 census.