The Gießen-Koblenz Lahn Valley is a bowl in western Hesse and eastern Rhineland-Palatinate in Germany that contains the lower course of the Lahn as well as the Limburg Basin. It falls within natural region no. 31 as defined by the BfN. It extends from Leun to the mouth of the Lahn into the river Rhine near Lahnstein. Despite its name it does not reach as far east as Gießen, but ends west of Wetzlar.
Natural divisions 310 Lower Lahn Valley 311 Limburg Basin 311.0 North Limburg Basin Hills 311.00 Ahlbach Börde Plateau 311.01 Elz-Hadamar Basin Edge 311.02 Schupbach-Hof Edge Plateau 311.1 Inner Limburg Basin 311.10 Linter Plateau 311.11 Villmar Basin 311.12 Runkel Lahn Valley Region 311.13 Limburg Lahn Valley Region 311.14 Diezer Pforte 311.2 South Limburg Basin Hills 312 Weilburg Lahn Valley Region 312.0 Gaudernbach Plateau 312.1 Weilburg Lahn Valley 312.11 Löhnberg Valley Region 312.12 Weilburg-Aumenau Lahn Valley 312.2 Edelsberg-Braunfels Plateau 312.21 Braunfels Plateau 312.22 Edelsberg Plateau
The Gießen-Koblenz Lahn Valley region is the western extension of the Marburg-Gießen Lahn Valley region (major unit 348). It continues to the west into the Moselle Valley (major unit 25), which separates it from the Middle Rhine Region (29). To the north it is bordered by the Westerwald and to the south by the Hintertaunus.