Graffiti writing was born in the streets of Philadelphia in the late 1960s. But it was in New York in the early 1970s that it became a full-fledged urban art, gradually taking over the landscape of the city, from its walls to its subway cars. In these years when this art form was emerging, graffiti pioneers laid its foundations through the constant game they played with the twenty-six letters of the alphabet, which they distorted and highlighted...