The Lahn is a , right (or eastern) tributary of the Rhine in Germany. Its course passes through the federal states of North Rhine-Westphalia (23.0 km), Hesse (165.6 km), and Rhineland-Palatinate (57.0 km).
It has its source in the Rothaargebirge, the highest part of the Sauerland. It meets the Rhine at Lahnstein, near Koblenz. Important cities along the Lahn include Marburg, Gießen, Wetzlar, Limburg an der Lahn, Weilburg and Bad Ems.
Tributaries to the Lahn include the Ohm, Dill, the Weil and the Aar. The lower Lahn has many dams with locks, allowing regular shipping from its mouth up to Runkel. Riverboats also operate on a small section north of the dam in Gießen.
The Lahn is a -long, right (or eastern) tributary of the Rhine in Germany. Its course passes through the federal states of North Rhine-Westphalia (23.0 km), Hesse (165.6 km), and Rhineland-Palatinate (57.0 km).
The Lahn originates at the Lahnhof, a locality of Nenkersdorf, which is a constituent community of Netphen in southeastern North Rhine-Westphalia, near the border with Hesse. The source area is situated along the Eisenstraße scenic highway and the Rothaarsteig hiking trail.
The river arises in the southeastern Rothaargebirge in the Ederkopf-Lahnkopf-Rücken ridge-line natural area. This ridge is the drainage divide between the Rhine and Weser, and, within the Rhine system, the watershed between the rivers Lahn and Sieg.
The source is at an elevation of and is located southwest of the high Lahnkopf. In the vicinity are also the origins of the Eder (5.5 km northwest of the Lahnhof) and the Sieg (another 3 km north). Whereas the Sieg takes the shortest route to the Rhine (to the west), the Lahn first runs in the opposite direction, paralleling the Eder for many kilometers.
The Lahn first flows in a northeasterly direction through the southeastern Rothaargebirge and its foothills. From about the Bad Laasphe community of Feudingen, it turns primarily to the east.
The section of the Lahn below the town of Bad Laasphe is geographically known as the Upper Lahn Valley (German: Ober Lahntal).