I found an art space for contemporary art in Berlin, which is open every day from 9am - 10pm, admission is free. So you can go there if closed all galleries and museums.
It's called 'art place berlin' and is located at the Park Inn on Alexanderplatz in the city centre. Yesterday I saw fantastic works by an American photographer for Tom Waits' Swordfishtrombones. There is also an informative website: http://www.art-place-berlin.com
currently in Berlin