Working in a city known more for freeways than museums, Judith Baca maybe the quintessential Los Angeles artist, painting not on canvas but on concrete. Since 1974 she has overseen the creation of roughly 550 murals in public spaces, providing summer work for inner-city kids while she brings color and life to highway underpasses and parks. "I want it to continue," Baca, 58, says of her work. "I want future generations to see it."

Now Baca is starting a massive restoration of her most famous piece, the 13-ft-high, half-mile-long Great Wall, which depicts world and L.A. history on a flood-channel wall. Some 400 youths—many from poor, crime-ridden areas—worked on the mural, and now some of their kids are working on the restoration. "People come first for Judy," says Priscilla Becker, 40, who, as a teen from a poor family, worked with Baca for three summers. Now CEO of a software company, Becker adds, "From Judy I learned that dreams are not just dreams."

Baca was teaching art in an inner-city park when she began planning murals to build bridges between rival gangs. She hopes the restoration—expected to cost $550,000 in public and private donations and take three summers and 250 kids—will meet the same goal. "All these people made the wall together," she says. "That's the story—what they made together."