The Rhein-Main Region is a metropolitan area in western Germany. The principal hub is Frankfurt am Main but several other important cities are included, for instance Wiesbaden, Mainz, and Darmstadt. The commuter belt stretches to Limburg in the North. About four million people live in the area, which in the relatively evenly populated Germany makes it to one of the more prominent population concentrations.

The growth of the area is chiefly to be traced to the favorable communications, that promoted an early industrialization. Today, the importance of productive industries are to a great extent substituted by that of banking, trade and logistics. The central location is still of importance: within six hours are Paris, Rotterdam, Hamburg, Berlin, Poland, the Czech Republic, Austria and Switzerland reached by truck or train.