The East Side Gallery in Berlin is an art gallery stretched along a remnant of the Berlin Wall. The first "painting" on it started in 1990. Measured at 1316 meters long and consisting of 105 paintings from artists from all over the world.
People of Berlin started to paint the west side wall of Berlin in 1961.
Due to the near ending of the Cold War people in Berlin started to paint on the east side of the Berlin wall. They were permitted to paint on the wall.
More Information about the East Side Gallery: https://www.visitberlin.de/en/east-side-gallery