Berlin cannot simply be defined by one single thing. It has many layers and people that live there are the ones that add them day by day. When visiting you will meet a very wide range of characters - from by-day businessmen, by-night ravers to complete aliens. And what makes it so incredible: they exist in an admiring respect to each other.
The reminder of the never sleeping human energy of the city can also be seen on the street walls with thickly layered up posters that every person visiting Berlin will undoubtedly remember.