#Fortification
Radar station
It looks like a bunker but it is the foundation of a huge radar. The Germans controlled the air with the so-called Würzburg radars.
It was a target-tracking radar, i.e. the antenna does not rotate but once a target is detected, it follows it continuously. In this way enemy bombers were followed, so that their own fighters could eliminate them. The range was approximately 30 km. The vulnerable connecting equipment was probably put up in the rest of the little shed on the right.