I suggest to anyone who is going to be in Prague during the next weekend not to miss the Prague Museum Night 2009 on Saturday. The sixth Prague Museum Night takes place on June 20th 2009 from 7 p.m. to 1 a.m. During the night, all museums, galleries, cultural monuments and other sites are open and free to public. A special museum public transportation is provided free as well, however a little bit crowded at that time. You can find more info at PMN.
So, anyone who will be around in that time, do not hesitate. Not only because it is free, but because of the exciting feeling of spending a part of a night at a museum. The time when things live their own lives. Haven't you seen the movie with Ben Stiller?? :-)