 After the looting of Hamburg by Vikings, in 845, the archbishopric of Hamburg was united with the bishopric of Bremen, and the archbishop's seat was moved to Bremen.Still, there was a cathedral chapter in Hamburg with several special rights, which started to build St. Mary's Cathedral.The incumbents of the Hamburg-Bremen see are usually titled Archbishop of Hamburg and Bishop of Bremen between 848 and 1072, however, some later archbishops continued the tradition of naming both dioceses until 1258.