A metropolis religious jurisdiction, or a metropolitan archdiocese, is an episcopal see whose bishop is the metropolitan bishop of an ecclesiastical province. Metropolises, historically, have been important cities in their provinces.
In the Latin Church, or Western Church, of the Catholic Church, a metropolitan see is the chief episcopal see of an ecclesiastical province. Its ordinary is a metropolitan archbishop and the see itself is an archdiocese. It has at least one suffragan diocese.
There are very few suffragan sees that have the rank of archdiocese, such as the Archdiocese of Avignon that is a suffragan of the Archdiocese of Marseille. Other non-metropolitan archdioceses are directly subject to the Holy See and are merely "aggregated" to an ecclesiastical province, without being part of it.
In the Eastern Catholic Churches, a metropolitanate is an autonomous church of a lower category than the patriarchal and the major archiepiscopal churches and is headed by a single metropolitan of a fixed episcopal see.