Frankfurt am Main, literally "Frank ford on the Main," is the most populous city in the German state of Hesse and a pivotal European metropolis. It anchors the Rhine-Main metropolitan region, Germany's second-largest, and serves as a de facto capital of the European Union, prominently hosting the European Central Bank. This global hub is a powerhouse in finance and commerce, featuring the Frankfurt Stock Exchange, Germany's busiest airport, and DE-CIX, the world's largest internet exchange point, alongside the renowned Frankfurt Book Fair. Historically a Free City for nearly five centuries and a significant site for Holy Roman Empire coronations, Frankfurt is now one of Europe's wealthiest and most culturally diverse cities, with half its population having a migrant background.