Between the districts of Treptow (east) and Kreuzberg (west) in Berlin, Germany,
you can find this old watchtower. As you (should) know, the wall separated East Berlin and West Berlin for 28 years and this tower was built to control the area.
Today it's a museum where young artists find a platform for their works. I just love the graffiti on this tower and so I made a small 3D model. Click on the google maps link to see the original place.