What is "rhein-main"

Rhein-Main may refer to:

• Rhein-Main Region, a metropolitan area in central Germany
• Rhein-Main Air Base, a former U.S. air base

The Rhein–Main was an express train that linked Frankfurt am Main with Dortmund in Germany and later with Amsterdam in the Netherlands. The train was named after the two rivers, the Rhine and the Main, that join west of Frankfurt. For most of its life, it was a Trans Europ Express (TEE).