A motorbike passes a traffic sign converted to street art in Kreuzberg district on June 26, 2014 in Berlin, Germany. Berlin, with its long tradition of counter-culture, has become a mecca for street art of all dimensions and messages. (Photo by Sean Gallup/Getty Images)

The giant mural titled “Under the Hand” by Maclaim Crew is visible on a building facade in Kreuzberg district on June 26, 2014 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

An elderly couple stop to look at street art at an intersection in Friedrichshain district on June 26, 2014 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

Street art and graffiti cover the entrance to an apartment building in Oranienstrasse in Kreuzberg district on June 26, 2014 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

People walk by street art in Kreuzberg district on June 26, 2014 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

People walk by a street artist's version of Kermit the Frog in Oppelner Strasse in Kreuzberg district on June 26, 2014 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

Street art behind a ground-level grate is visible in Kreuzberg district on June 26, 2014 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

Street art comissioned by a local renters' association depicting the experiences of immigrants in Berlin is visible on the wall in Skalitzer Strasse in Kreuzberg district on June 26, 2014 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

Street art and graffiti cover a wall in Dirschauer Strasse in Friedrichshain district on June 26, 2014 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

A couple stop to look at two murals of street art in Kreuzberg district on June 26, 2014 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

A boy on a bicycle rides past street art on the wall of an apartment building in Skalitzer Strasse in Kreuzberg district on June 26, 2014 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

A street art mural by Da Mental Vaporz, or DMV, is visible in Friedrichshain district on June 26, 2014 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

A small figure of Charlie Chaplin peeks out from the entrance to a cafe in Oranienstrasse in Kreuzberg district on June 26, 2014 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

Dutch artist Ms. X works at her outdoor studio under a mural titled “Brothers” by Blu and JR at the Cuvrystrasse squat in Kreuzberg district on June 26, 2014 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

A man on a bicycle rides past stret art in Skalitzer Strasse in Kreuzberg district on June 26, 2014 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)