Frankfurt, officially Frankfurt am Main (Literally "Frankfurt on the Main", ), is a metropolis and the largest city in the German state of Hesse and the fifth-largest city in Germany, with a 2015 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 to the east of Frankfurt's CBD, 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. It's the site of many global and European corporate headquarters. Frankfurt Airport is among the world's busiest. Frankfurt is the major financial centre of the European continent, with the HQs of the European Central Bank, German Federal Bank, Frankfurt Stock Exchange, Deutsche Bank, Commerzbank, DZ Bank, KfW, several cloud and fintech startups and other institutes. Automotive, technology and research, services, consulting, media and creative industries complement the economic base. Frankfurt's DE-CIX is the world's largest internet exchange point. Messe Frankfurt is one of the world's largest trade fairs. Major fairs include the Frankfurt Motor Show, the world's largest motor show, the Music Fair, and the Frankfurt Book Fair, the world's largest book fair.
How many are larger?
the fifth-largest city in Germany