From the 1970s onwards, Burhan Dogancay photographed urban walls all over the world.
Elsewhere, activists in Russia have used painted caricatures of local officials with their mouths as potholes.
A 2006 exhibition at the Brooklyn Museum displayed graffiti as an art form that began in New York's.
The project today known as "Walls of the World" comprises about 30,000 individual images.
It spans a period of 40 years across five continents and 114 countries. 1982, photographs from this project comprised
a one-man exhibition.
In Australia, art historians have judged some local graffiti of sufficient creative merit to rank them firmly within the arts.