The Rhineland is normally Bonn, Cologne, Düsseldorf area about 250km north of Rammstein.
So what area do you mean by Rhineland?
In case you mean the Rammstein area. This is a interesting trip.
Maginot Line in France/Alsace
http://en.wikipedia.org/wiki/Maginot_Line
http://www.lignemaginot.com/menu10/indexen.htm
You can visit some of the old bunkers which are quite extensive. Even in summer you will need a jacket inside the bunker.