Frankfurt, officially the City of Frankfurt am Main, is a metropolis and the largest city in the German state of Hesse and the fifth-largest city in Germany. Frankfurt was a city state, the Free City of Frankfurt, for nearly five centuries, and was one of the most important cities of the Holy Roman Empire; it lost its sovereignty in 1866.
In 2015, Frankfurt had a population of 732,688 within its administrative boundaries, and 2.3 million in its urban area. The city is at the centre of the larger Frankfurt Rhine-Main Metropolitan Region, which has a population of 5.5 million and is Germany's second-largest metropolitan region after Rhine-Ruhr. Since the enlargement of the European Union in 2013, the geographic centre of the EU is about 40 km to the east of Frankfurt's central business district, the Bankenviertel. Frankfurt is culturally and ethnically diverse, with around half of the population, and a majority of young people, having a migration background. A quarter of the population are foreign nationals, including many expatriates.
Frankfurt is an alpha world city and a global hub for commerce, culture, education, tourism and transportation.