With two weeks of work on Katharina Grosse’s psychylustro set to begin today (weather permitting), the Mural Arts Program will brighten up five miles of Amtrak’s Northeast Corridor with striking color. But what about the colors already there—the decades old graffiti? Brad Maule discusses conflicts and philosophies with the artist and Mural Arts’ Jane Golden

Mural Arts may paint most of Philly’s walls and get all the press, but there are plenty of murals created outside the system. Peter Woodall and Katrina Ohstrom survey the idiosyncratic field