The Archbishopric of Bremen, or Prince-Archbishopric of Bremen — not to be confused with the former Archdiocese of Bremen, and the modern Archdiocese of Hamburg, founded in 1994 — was an ecclesiastical principality (787–1566/1648) of the Holy Roman Empire, which after its definitive secularization in 1648, became the hereditary Duchy of Bremen. The prince-archbishopric, which was under the secular rule of the archbishop, consisted of about a third of the diocesan territory. The city of Bremen was de facto and de jure not part of the prince-archbishopric. 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.