Westbau 1938 -Julius Berger Tiefbau AG Berlin
This Medal was given out for the cooperation between a private company -Julius Berger- and the German Military for work on the Germany's Western defenses (Westwall).
In your case it was given for the construction of the part in the Karlsruhe (Baden) area.
It's interesting to note that Julius Berger and his family was deported to a concentration camp and his company was taken over by the state.
Overall very good condition, look better in hand.