The Lahn is a river in Germany that serves as a right tributary of the Rhine. It flows over a total length of 245.6 kilometres (152.6 miles).
The river's course passes through three German federal states: North Rhine-Westphalia, where it flows for 23.0 kilometres; Hesse, covering 165.6 kilometres; and Rhineland-Palatinate, spanning 57.0 kilometres.