Ground Release, an international arts and culture exchange program, recently staged an event in London. Featured were graffiti artists Opium (IT), Zoer (FR), Towns (UK), Kem5 (US), Score (GER), and Roid (UK). That's five writers representing four nations. Each produced a mural, and all combined for a thrilling series of new works. Click the thumbs to check the finished product and watch the film below for the full story.