Graffiti and street art have been highly controversial forms of expression for decades, hated by art snob and building caretaker alike.
The people who complain about it the most, however, are the city officials who clash with artists and taggers over their creations.
Interestingly, this battle has done nothing to lessen street art's popularity. And now, some experts say, that popularity could do what city officials couldn't: threaten the very essence of this short-lived art form.