There's nothing underneath except rainbow RGB lights that come on at night. I can't see any construction work being done. it's perfectly accessible to the general public.  There's a public seating area on top of it which is also not under any construction. Bunch of benches with backrests up here (as well as a great view from the balcony!).

Attached photo(s):
https://westnordost.de/p/192806.jpg
https://westnordost.de/p/192807.jpg
https://westnordost.de/p/192808.jpg