In 1989 the Berlin wall fell and the reunification of East and West Germany began. However, 31 years later you can still see a scar across the city, in fact it is so noticeable you can see it from space. When looking at Berlin from space at night you can see the clear divide between East and West Berlin.
Why? Because the color of the streetlights. On the east side, the streetlights have a yellow tint, on the west they are whiter.