One of the most beautiful pieces of Berlin actually is a piece of another city (Al-Hillah, Iraq). Normally Berliners are laid back and like to hang around, drink beer and chat till sunrise. Sometimes they do get excited though, and then they start taking old war-battered stones and piecing them together to (re)form walls. The results are great as can be seen all over Berlin, but the Ishtar gate in the Pergamon museum is where they’ve really outdone themselves.
As its name suggests this bibliophile cabinet accommodates finds from many centuries and areas. Everything - junk and treasures - from the floor up to the ceiling. Don’t be shy to ask the owner if you’re looking for something specific.
Kw is a great art institute situated at the backyard of a very eastern part of town, place for many other small galleries. Auguststrasse is worth the walk and Kw is worth the stop.
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!