Hesse or Hessen, officially the State of Hesse, is a landlocked state in Germany. Its capital city is Wiesbaden, and the largest urban area is Frankfurt am Main, 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.