Lahn was a city which was created on January 1, 1977 when the two cities of Gießen and Wetzlar were merged. It was named after the river Lahn to make the merger one of equals. However, as the merger was very unpopular as well as inefficient—it had been imposed on the cities against the will of almost all inhabitants—it was rescinded on July 31, 1979; so the city Lahn only existed for two and a half years.

Coordinates: 50°34′20″N 8°35′20″E / 50.57222°N 8.58889°E / 50.57222; 8.58889