There's nothing more revigorating during the dark winter days than spending a couple of hours in a sauna. Germans have mastered the art of sauna and you can find amazing pieces of architecture in the public swimming pools (Stadtbad). I find Stadtbad Neukölln very peculiar in its neoclassic architecture and it's definitely a wallet-friendly option to enjoy some sauna time there. Be prepared to be naked in front of man and woman!
Wim Wenders shot Wings of Desire here. It's a quiet place to work and definitely a gorgeous place to visit. Combine it with a visit to the Philharmonic, just across the street. Affiliation is 30 euros per year and you have lots of desks all over the library to choose from.
The central ‘Mitte’ area of Berlin is packed tight with galleries and museums, which means you can cram a lot into a short amount of time, if that’s what you want.
The best of the lot is the Me Collectors Room, which shows off large chunks of the Thomas Olbricht collection alongside other contemporary private artworks. The permanent ‘Wunderkammer’ display offers over 200 pieces from the Renaissance and the Baroque periods, with a solid focus on the strange and macabre. There’s even a Mark Ryden original that fits in nicely.