Just until recently this place used to be one big old Aphoteke (Pharmacy). They have kept the Apotheke's dark wood Art Deco charm to use in benefit of great coffee and fantastic brunch (try the french toast and you'll see I'm not lying).
While strolling around Mitte, check out the flagship store of Berlin´s cult women fashion brand. (And try a delicious cinnamon bun at Zeit für Brot next door.)
Situated in the patio of the Kunst-Werke, a well established exhibition house for contemporary art, this cafe features mirror-walls and a selection of nice cakes and lunch menu.
I never knew this neighbourhood existed and went to visit a friend and was instantly transported out of Berlin into some sort of 50's utopia.
"The Hansaviertel is a prime example of modern architecture and urban planning in the fifties in Berlin.
36 individual buildings or ensembles still form the model of modern architecture and urban planning of the 1950s. The southern part of the war-damaged Hansaviertel, which lies between the S-Bahn line and Tiergarten, was chosen as the central demonstration area of the International Building Exhibition in order to present the "city of tomorrow" - in deliberate contrast to the East Berlin Stalinallee and the restored tenement barracks." - berlin.de
Also visit The Akademie der Künste, if not for the art then the architecture alone.