In the fifeties and early sixties the art style of the décollage or déchirage came into being. It embelished the architecture with very early forms of Streetart.
Even today it is widespread; but I have a hunch that is is not anymore a handfull of artists who make these artworks but 'informal', improvising artists.
After I found some nice recent examples in the métro in Paris, I also stumbled on who seemed to be the 'artist'. Did I?