Frankfurt am Main commonly known as Frankfurt, or Frankfort on the Main is the largest city in the German state of Hesse and the fifth-largest city in Germany, with a 2011 population of 695,624. 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.
Frankfurt is the financial and transportation centre of Germany and the largest financial centre in continental Europe. It is the seat of the European Central Bank, the German Federal Bank, the Frankfurt Stock Exchange, and the Frankfurt Trade Fair, as well as several large commercial banks, e.g. Deutsche Bank, Commerzbank and DZ Bank. Frankfurt Airport is one of the world's busiest international airports, Frankfurt Central Station is one of the largest terminal stations in Europe, the Frankfurter Kreuz is one of the most heavily used Autobahn interchanges in Europe. Frankfurt lies in the former American Occupation Zone of Germany, and it was formerly the headquarters city of the U.S. Army in Germany. Frankfurt's DE-CIX is the world's largest internet traffic exchange point.
Frankfurt is an international centre for finance, commerce, culture, transport, education, and tourism. It is therefore considered an alpha world city as listed by the Loughborough University group's 2010 inventory. It was ranked 10th among global cities by the Global Power City Index 2011, 11th by the Global City Competitiveness Index 2012 and 7th among international financial centers by the International Financial Centers Development Index 2012.
In 2011, the human-resource-consulting firm Mercer ranked Frankfurt as seventh in its annual "Quality of Living" survey of cities around the world. According to The Economist cost of living survey, Frankfurt is Germany’s most expensive city, and the 10th most expensive in the world