5/10 K Rainbowrun 2026

Frankfurt am Main, usually shortened to Frankfurt, is the most populous city in the German state of Hesse. Its 778,589 inhabitants as of 2025 make it the fifth-most populous city in Germany. Located in the foreland of the Taunus on its namesake river Main, the city forms a continuous conurbation with Offenbach; its urban area has a population of more than 2.7 million. Frankfurt is the heart of the larger Rhine-Main metropolitan region, which has a population of more than 5.8 million and is Germany's fourth-largest metropolitan region after the Rhine-Ruhr region, the Berlin/Brandenburg Metropolitan Region and the Munich Metropolitan Region. Home to the European Central Bank, the city serves as one of the four institutional seats of the European Union. Frankfurt is classified by the GaWC as an Alpha world city.