Berlin, Germany

Berlin's Kreuzberg and Friedrichshain districts contain the densest concentration of politically charged street art in Europe, a direct legacy of the city's Cold War division and the explosion of creative energy that followed the Wall's fall in 1989. The East Side Gallery — a 1.3-kilometre section of the original Berlin Wall — hosts 105 murals by artists from 21 countries, making it the longest open-air gallery on Earth. Berlin's underground scene includes the notorious 1UP crew, whose tags appear on trains across the continent, and artists like BLU, whose vast political murals on Cuvrystrasse defined a generation of European street art.