Trier, formerly and traditionally known in English as Trèves and Triers, is a city on the banks of the Moselle in Germany. It lies in a valley between low vine-covered hills of red sandstone in the west of the state of Rhineland-Palatinate, near the border with Luxembourg and within the important Moselle wine region.

The elector of Trier was one of the prince-electors of the Holy Roman Empire and, in his capacity as archbishop, administered the archdiocese of Trier. The territories of the electorate and the archdiocese were not, however, equivalent.