Update 2019: While I do appreciate the accessibility of such a great view over the city that this rooftop bar provides, Klunkerkranich has become quite the tourist magnet in Neukölln and almost impossible to enjoy as a resident. For visitors, I do recommend hanging out up there if you get to it, but apart from the view, everything else is kinda meh.
There have been some (relatively secret) raves on the upper parking deck of the Neukölln Arkaden, but now they have been officially transformed into a summer garden, bar, rooftop-chill out space that invites you to spend the evenings watching the sun go down while sipping on cool drinks.
We were astonished when we first saw what the people behind the Klunkerkranich have made out of the parking lot deck! Lots of wood, space, and love put into the project. The gardens and little beets are a fantastic idea that, by time, will add a lush green scenery to the (hopefully everlasting) blue horizon.