We went to Berlin for the weekend, just the two of us and had a great time.
It's a really nice city, warm, inspiring and friendly, and with tons of cool street art.
Obviously we went to see Brandenburger tor, der Reichstag, Checkpoint Charlie, The Holocaust memorial etc. Which are all very interesting places and at the same time very haunting.
Of course we visited Bauhaus Archiv, which just isn't my thing - I don't think that stuff is made for humans. It's absolutly drained for life, fantasy, just straight lines and cold boxes.
But if you are planning to visit Berlin, you must see the Design panoptikum museum, it's steampunk meets Frankensteins laboratory, a fantastic place.