Staatsbibliothek zu Berlin, Haus 1
, Unter den Linden 8
Made famous in Wim Wenders' Wings of Desire, this is one of Hans Scharoun's architectural masterpieces. You have to pay to get in, but if you're an architecture buff, it's worth the entry fee! Remember to be quiet as it's a favorite for students who use it to cram for their examinations.