I suggest stopping by the Berlin Art Market by the Zeughaus to pick up a locally created art piece. Since the market is located in the center of Museum Island it's easy to reach.

"Idealpassage" in Berlin takes you on a historic walk - this passage reveals a complex from a century ago that served as a model for 'social housing'...

"Oxfam Schöneberg" in Berlin deals in second-hand books! It offers a surprisingly interesting variety of international books...

"Buchhandlung Moritzplatz" in Berlin is hosted by Aufbau Verlag, once the biggest belles-lettres publisher in Easy Germany and still one of my favorites!

"Troika" is a nice little bookshop among the Prenzlauer Berg bars and restaurants. It's a little nostalgic treasure - you're lucky if you find it open!

"Unterwegs" is a magnificent antiquarian bookstore specialised in architecture, photography, Berlin-Brandenburg and travel. Very aesthetically pleasing!