Template:Geobox Ahr is a river in Germany, a left tributary of the Rhine. Its source is at an elevation of approximately 470 metres above sea level in Blankenheim in the Eifel, in the cellar of a timber-frame house near the castle of Blankenheim. After 18 kilometres it crosses from North Rhine-Westphalia into Rhineland-Palatinate.
The Ahr flows through the towns of Schuld, Altenahr and Bad Neuenahr-Ahrweiler. Between Remagen and Sinzig (south of Bonn), at about 50 m above sea level, it flows into the Rhine. The length is roughly 89 km, of which 68 km is within Rhineland-Palatinate. The Ahr has a gradient of 0.4% in its lower course, and 0.4-0.8% in its upper course.
The Ahr and its tributaries are a main drainage system of the eastern Eifel. The watershed is approximately 900 km². Tributaries of the Ahr are (from the mouth to the source): Harbach (Ahr), Hellenbach, Bachemer Bach, Leimersdorfer Bach, Liersbach, Vischelbach, Sahrbach, Kesselinger Bach, Armuthsbach, Dreisbach (brook), Eichenbach, Adenauer Bach, Trierbach and Ahbach.
There were isolated settlements in the Ahr valley beginning at the latest in Roman times, evidenced by the Roman villa near Ahrweiler. Owing to their isolated location, the upper and middle parts of the course were sparsely populated.
That changed from the mid-19th century. The development of the settlements, the traffic routes and the agricultural areas in the Ahr valley led to the fact that the riverbed was fixed.
The Ahr valley makes up the Ahr wine region, which is small but noted for its red wines made from the Pinot noir variety.