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 Moselle is a river that rises in the Vosges mountains and flows through north-eastern France and Luxembourg to western Germany. It is a left bank tributary of the Rhine, which it joins at Koblenz. A small part of Belgium is in its basin as it includes the Sauer and the Our.