In the homeland of Banksy, graffiti remains both a popular and prohibited art form. Yet the lure of the spray can is great, so if you’d like to leave your mark on London without breaking any laws, make your way to Leake Street, the city’s officially-sanctioned graffiti zone. As you and your friends leave the tube at Waterloo Station, keep the glass dome covering the rail lines to your left as you head through the parking lot. When you come to a large white billboard near the florescent glow of the tunnel entrance, make sure to give it a once over. After your crew educates themselves on the tunnel rules (take litter with you, etc.) crack open your backpack stuffed with spray paint cans and set to work. Roam through the tunnel for a little inspiration as you search out the perfect spot for your mural or tag. As a legal graffiti spot, time isn’t a factor, and the pieces lining the tunnel are far more intricate than your typical freeway overpass throw-ups. Colors explode from behind blocky stenciled signatures, lifelike portraits stare out from cold concrete walls, and halfway-completed landscapes are overlain with splattered tags and squiggles, making it the perfect place for your pals to set up shop. After you’ve shaken and sprayed to your heart’s content, stand back and admire your piece before grabbing the guys to snap a picture to remember all your hard work. By the time you come back, your ephemeral creation will be overlaid with several levels of paint, making a brand new canvas for your crew’s next masterwork.