This is a memorial to Georg Elser, the lesser-known attempted assassin of Adolf Hitler. A German biopic on Elser came out a few years ago and I recently watched it. I had heard of the man before, but his attempt on Hitler's life has just never been as widely publicized as von Stauffenburg.
This message can be found just steps away from Elser's profile. It reads, "that the conditions in Germany could only be changed by eliminating the current leader." True words... More signs can be found at Signs, Signs.