The S-Bahn in Frankfurt Germany is the city's extensive urban rail
system. It links central Frankfurt (Hauptbanhof station) to the
Frankfurt International Airport and other communities in the region. The S-Bahn
trains normally run at ground level but occasionally travel underground,
like the U-Bahn.
Passengers can travel on the S-Bahn from Frankfurt Hauptbanhof to the
Frankfurt Airport and on the Mainz. From Mainz, one can take an
inexpensive boat cruise down the world-famous Rhine River.