Dutch artists Jeroen Koolhaas and Dre Urhahn, who collaborate under the name Haas & Hahn, painted  large-scale murals that span entire city blocks—and transforming the hardscrabble slums of Rio de Janeiro into beautiful places to live.

For the FAVELA PAINTING PROJECT in the slum of Santa Marta, they trained local youth to work with them to convert more than 34 houses and 700 square meters into an eclectic rainbow canvas. The local youth learned to work with different types of paint and to navigate scaffolding—and they were paid for their month-long painting effort.

Haas & Hahn first visited the favelas, or slums, in 2005 when they filmed an MTV documentary about favela hip-hop. They decided to stay to work with local youth and help improve these bleak and often violent urban areas. Their first project was a huge mural in Santa Marta called Boy Flying a Kite. The duo’s eventual goal is to raise enough money to one day cover an entire hillside favela in murals.