German artist Jan Vormann has used lego bricks to patch up crumbing buildings. Starting in Bocchignano, Italy (top picture)- Dispatched has now gone on be a world wide phenomenon. Click here to find lego bricks in other countries. Second picture from Amsterdam.
The use of the very durable plastic bricks, brings a small amount of bite-sized fun into an otherwise very boring building and is far more cheaper than tearing down the wall.