Last saturday there was a HUGE demo with the theme "Capitalism is the Crisis" which quickly degenerated into vandalism (you'll find enough articles, media, pictures and videos online). Nearly 500 people were arrested, a few ended up in the hospital. Let's wait what will happen from now on...
As far as I can tell, both sides, aggressive demonstrants as well as the cops, were guilty for this massive escalation. Since I couldn't assist, I can only provide with the photos I took today. Either the clearing-up operations already did their job or the vandalism wasn't as bad as I imagined; the Berliner Straße seemed nearly untouched. But entering the Bethmannstraße which leads to the beginning of the Kaiserstraße you could see a field of destruction - all of the shop windows were shattered. I only took a few pictures because there was so much police so I didn't dare to stay long.
By the way, the Occupy Movement doesn't approve this kind of violence.
In my neighbourhood Bornheim the Commerzbank on the corner Berger Straße/Höhenstraße was demolished as well. Since the demo didn't come far this must've happened afterwards.