Claudine C: Artbase was an urban art fest hosted in an abandoned sanatorium in the outskirts of Berlin. In a few dilapidated buildings, artists transformed empty rooms into small exhibitions. You'll see the evidence of paintball wars on the walls as well. Also on the theme of urban art, I can recommend the documentary Unlike-U, which is about the microcosm of graffiti artists who tag s-bahn trains, and some have been doing it for almost 20 years. For the hard core it becomes their primary world, many refer to it as their job. Fascinating portrait of people who devote almost their whole being on very fleeting artistic expression and the adrenaline rush of their cat and mouse game with the police.