Frankfurt am Main (Frankfurt on the Main), commonly known as Frankfurt, is the largest city in the German state of Hessen and the fifth-largest city in Germany, with a 2012 population of 704,449. The urban area had an estimated population of 2,300,000 in 2010. The city is at the centre of the larger Frankfurt Rhine-Main Metropolitan Region which has a population of 5,600,000 and is Germany's second-largest metropolitan region. Since the expansion of the European Union in 2007, the geographic midpoint of the European Union is about 40 kilometres east of Frankfurt am Main.
http://en.wikipedia.org/wiki/Frankfurt