The development of settlements and transportation routes (including three railway lines) and the expansion of the area used for agriculture in the Ahr valley led to the narrowing and constraint of the riverbed.

The Ahr rises in the middle of the village of Blankenheim, in the Eifel region of the German state of North Rhine-Westphalia, in the basement of a timber-framed house in an enclosed spring at a height of 474 m above sea level (NHN).

From Reimerzhoven the valley sides are dominated by vineyards, especially on the south-facing slopes north of the river, particularly around the villages of Mayschoß, Rech, Dernau and Marienthal.

The last narrow point in the Ahr valley occurs below the Bunte Kuh ("coloured cow"), a rock formation that almost reaches the river and leaves little room for road and railway.

The valley floor between Bad Bodendorf on the northern side and Sinzig on a terrace in the south is dominated by agriculture and fruit and vegetable growing.

The mouth of the Ahr lies on the plain of the Golden Mile, between the Remagen district of Kripp and the town of Sinzig at a height of about 53 m above NHN[1].

The Red Wine Trail runs through the southern slopes of the lower Ahr Valley, passing inter alia the former government bunker.