Friends who hosted us for a few days in Alsace referred to “the bunkers” a few times. While heading to Berne the one day we stopped there - there is a small nature center, a pond, a few bee hives, and… two bunkers!
“The bunkers” are a blockhouse and pillbox belonging to the old Maginot Line. Sitting on the ridge with a nice view of Berne across the river to the east.