Thanks for your feedback, Alan :-)
I'm a bit undecided about the taggers: On one hand I agree, that the original artworks absolutely deserve to be conservated in their initial state. On the other hand, I pretty much like the idea of living art, that interacts with the viewers and still develops. I mean, it's a street art gallery, not a museum and this way the wall is pretty much used like it was in the days of the cold war (at least in West-Berlin).