Gießen (Giessen Giessen pronunciation in German.ogg) is a city in the federal state (Bundesland) of Hesse in Germany, capital of both the Gießen district and the Gießen region . As of 2003 there are approximately 72,909 inhabitants.

The history of the city goes back to 775, when the first to-be suburbs "Wieseck" and "Unsenheim" were first mentioned. Gießen itself was founded by Graf Wilhelm von Gleiberg as a waterside-castle. In 1607, the University of Gießen was founded.

Wilhelm Liebknecht, founder of the Social Democratic Party of Germany, was born on 29 March 1826 in Gießen.

Heavy bombing destroyed about 75% of Gießen in 1944, including most of the city's historic buildings.

In 1977 Gießen was merged with the neighboring city Wetzlar to form the new city Lahn, however this attempt to reorganize the administration was very unpopular and was reverted in 1979.