"But their blend of 'guerrilla activism' is harder to pull off in Philadelphia, with its layers of bureaucracy, than in the favelas. ... In Philadelphia, just finding the owners of the buildings — many are absentee landlords with no other ties to the neighborhood — has been a struggle. Another problem is that some buildings are so decrepit that there’s a danger they’ll fall on the painters." —New York Times on Haas and Hahn's Mondrianesque transformation of buildings on Germantown Ave.