Basking in the warm glow of the 2012 Cultural Olympiad, the "See No Evil" festival unabashedly celebrated street art in Bristol, UK, with thousands of...

Opening under cover of night somewhere in Paris, four stories beneath la rue, a secret subterranean gallery in a sealed tunnel appears suddenly. While activity on the street overhead is hectic and dense with cars, trucks and pedestrians, the dry dust is ankle-high here in this darkened, silent morgue—its cool, dank air now permeated with fresh aerosol. The Underbelly has been here, and if you discover this curated collection of Street Art and graffiti in the chilled dim light, you are officially lost. And lucky.

The unprecedented growth of the global grassroots art movement can be directly traced to digital photography and the people behind the camera.