Trier, historically called in English Treves (German pronunciation: [ˈtʁiːɐ] ( listen); French: Trèves, IPA: [tʁɛv]; Luxembourgish: Tréier; Italian: Treviri; Latin: Augusta Treverorum; the Latin adjective associated with the city is Treverensis) is a city in Germany on the banks of the Moselle. It is the oldest city in Germany, founded in or before 16 BC.

Trier lies in a valley between low vine-covered hills of ruddy sandstone in the west of the state of Rhineland-Palatinate, near the border with Luxembourg and within the important Mosel wine region.

The city is the oldest seat of a Christian bishop north of the Alps. In the Middle Ages, the Archbishop of Trier was an important prince of the church, as the Archbishopric of Trier controlled land from the French border to the Rhine. The Archbishop also had great significance as one of the seven electors of the Holy Roman Empire.