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theCrag.com is a free guide for rock climbing areas all over the world, collaboratively edited by keen rock climbers, boulderers and other nice folks.
You can log all your routes, connect and chat with other climbers and much more...
Despite the complete absence of natural rock formations, Berlin still offers some remedies for the vertically-addicted: artificial climbing walls, gyms, chiselled bunkers and semi-legal buildering. With more than 100 places to climb, you should be able to get pumped. A nice overview of all locations can be found at http://www.klettern-in-berlin.de (in German).