Trier (French: Trèves, Luxembourgish: Tréier; Latin: Augusta Treverorum; the Latin adjective associated with Trier is Treverensis) is a city in Germany on the banks of the Moselle River. It is the oldest city in Germany, founded in or before 16 BCE.
Trier lies in a valley between low vine-covered hills of ruddy sandstone in the west of the state of Rhineland-Palatinate, near the German border with Luxembourg and within the important Mosel wine-growing region.
Trier is the oldest seat of a Christian bishop north of the Alps. In the Middle Ages, the Archbishop of Trier was an important ecclesiastical prince, as the Archbishopric of Trier controlled land from the French border to the Rhine. He was also one of the seven electors of the Holy Roman Empire.
With an approximate population of 100,000 Trier was, until 2005, ranked fourth alongside Kaiserslautern among the state's largest cities; after Mainz, Ludwigshafen, and Koblenz. The nearest large cities in Germany are Saarbrücken, some 80 km southeast, and Koblenz, about 100 km northeast. The closest city to Trier is the capital of Luxembourg, some 50 km to the southwest.
Trier is home to the University of Trier, the administration of the Trier-Saarburg district and the seat of the ADD (Aufsichts- und Dienstleistungsdirektion), which until 1999 was the borough authority of Trier. It is one of the five "central places" of the state of Rhineland-Palatinate. Along with Luxembourg, Metz and Saarbrücken, fellow constituent members of the QuattroPole union of cities, it also forms a central place of the greater region encompassing Saar-Lor-Lux (Saarland, Lorraine and Luxembourg), Rhineland-Palatinate, and Wallonia.