The Ahr valley is named after the Ahr, a left tributary of the Rhine in Germany. It begins at the Ahr spring (Ahrquelle) in Blankenheim in the county of Euskirchen and runs generally eastwards. At its southernmost point it enters the county of Ahrweiler, and hence the state of Rhineland-Palatinate. Running through the collective municipality of Adenau the valley bends northeast at its confluence with the Adenauer Bach and reaches the collective municipality of Altenahr, from where it resumes its characteristic west to east course, albeit interrupted by meanders. Here begins the section that is known as the Ahr valley (Ahrtal) in a touristic sense. Here it is characterized by vineyards on the south-facing slopes and a picturesque rocky landscape, carved out by the river creating a 300 metre deep gorge in the Ahr Hills. In the next stage the Ahr reaches the area of the county town of Bad Neuenahr-Ahrweiler, before finally discharging into the Rhine south of Remagen in the borough of Sinzig.

Ahr is a river in Germany, a left tributary of the Rhine. Its source is at an elevation of approximately 470 metres (1,540 ft) above sea level in Blankenheim in the Eifel, in the cellar of a timber-frame house near the castle of Blankenheim. After 18 kilometres (11 mi) it crosses from North Rhine-Westphalia into Rhineland-Palatinate.