The Archdiocese of Bremen (also Archdiocese of Hamburg-Bremen, , not to be confused with the modern Archdiocese of Hamburg, founded in 1994) was a historical Roman Catholic diocese (787–1566/1648) and formed from 1180 to 1648 an ecclesiastical state (continued under other names until 1823), named Prince-Archbishopric of Bremen within the Holy Roman Empire. The prince-archbishopric consisted of about a third of the diocesan territory. The city of Bremen was de facto (since 1186) and de jure (since 1646) not part of the prince-archbishopric but belonged to the archdiocese. Most of the prince-archbishopric lay rather in the area to the north of the city of Bremen, between the Weser and Elbe rivers. Even more confusingly, parts of the prince-archbishopric belonged in religious respect to the neighbouring diocese of Verden, making up 10% of its diocesan territory.