New York is the historic hub of old-school graffiti, and Banksy has gone from marking London public spaces to making a mark in its contemporary art scene, but these days it's São Paulo that's producing the steadiest stream of world-class graffiti artists. Three of them, Tinho, Pato, and Flip, will be using the interior walls of Brazil's U.K. embassy and London's Gallery 32 for a spree of spray-painting to commemorate today's opening of London's first show focusing on Brazilian street art. According to Olivia Connelly, of the city's O Contemporary gallery, which is co-sponsoring "Street Art Brazil" at the embassy, "Urban art is by far the most significant global movement since Pop art, and Brazil is now considered by many to be the most important root of this movement."