Founded by the Celts in the late-4th century BC as Treuorum, it was later conquered by the Romans in the late-1st century BC and renamed Trevorum or Augusta Treverorum (Latin for "The City of Augustus among the Treveri"). Trier may be the oldest city in Germany. It is also the oldest seat of a bishop north of the Alps. In the Middle Ages, the Archbishop-Elector of Trier was an important prince of the church, as the archbishop-electorate controlled land from the French border to the Rhine. The Archbishop-Elector also had great significance as one of the seven electors of the Holy Roman Empire.