This isn’t the street art you’re used to- it isn’t created with spray paint or stencils, and it doesn’t mar the face of the urban environment in Paris. In fact, this unusual form of street art beautifies the cityscape, replacing advertising eyesores with classical works of art.
This is the work of street artist/city beautifier Etienne Lavie, who is on a mission to replace billboards all over the city of Paris with something people actually want to look at, such as classical paintings like "Liberty Leading The People" by Eugene Delacroix, in a project called "OMG who stole my ads?"
Eugene's cause is truly noble, although it's doubtful that the advertisers will agree when they find out that their billboards have been appropriated.
-Via Flavorwire
This is why I'm not sure it's noble. Those spaces are the rental property of the advertisers. They paid for that space.
It would be like if Lavie rented space in an art gallery to show his work, only to discover that advertisers and broken in and covered up his artwork with billboards.