Crossing to Kreuzberg.
These were the walls that went along the entrance to Babylon. I think between like 2 and 3 thousand years old.
There is an an abandoned airport in Berlin called Berlin-Tempelhof. It was where they flew the airlifts out of when the wall was up (I believe). It was abandoned in 2008 and then remade into a park. It's pretty incredible riding your bike down an airplane runway.