Wiesbaden is the capital of the German state of Hesse, and the second-largest Hessian city after Frankfurt am Main. With around 283,000 inhabitants, it is Germany's 24th-largest city. Wiesbaden forms a conurbation with a population of around 500,000 with the neighbouring city of Mainz. This conurbation is in turn embedded in the Rhine-Main Metropolitan Region—Germany's second-largest metropolitan region after Rhine-Ruhr—which also includes the nearby cities of Frankfurt am Main, Darmstadt, Offenbach am Main, and Hanau, and has a combined population exceeding 5.8 million.

Hesse or Hessia, officially the State of Hesse, is a state in Germany. Its capital city is Wiesbaden, and the largest urban area is Frankfurt, which is also the country's principal financial centre. Two other major historic cities are Darmstadt and Kassel. With an area of 21,114.73 square kilometers and a population of over six million, it ranks seventh and fifth, respectively, among the sixteen German states. Frankfurt Rhine-Main, Germany's second-largest metropolitan area, is mainly located in Hesse.