The See of Algiers founded in the second century at Icosium did not survive the Arabic conquest. In 1632, several missions were established in Algeria; soon after, an apostolic-vicar was installed there, who, towards the end of the seventeenth century had under him the pro-vicar of Tunis and the prefect of Tripoli. The Diocese of Alger was re-established on 10 August 1838 as a suffragan of the Archdiocese of Aix, France. On 25 July 1866 it was elevated to an archdiocese and lost the territory required to form two new dioceses.
The church of Algiers honours in a special manner the memory of several holy confessors of the Order of Our Lady of Mercy for the Redemption of Captives. Among them are Saint Peter Armengaud (thirteenth century), confessor at Algiers. It cherishes also a particular veneration for the memories of Blessed Raymond Lully who died at Bougie in 1325, and the Venerable Geronimo, buried alive at Algiers in 1569.
Suffragan Dioceses include