They built a little hill so spotters can overlook the runway and fences from a higher position. There‘s also an old MI-8 next to it that was converted to a snack bar, it‘s pretty sweet to hang out for the day.
Looking at this they seem somewhat of a german specialty, but now with entry fees at bigger locations.
https://eu.usatoday.com/story/travel/columnist/hobica/2013/1...