On a scaffold five meters off the ground, artist Meg Saligman uses her paintbrush to carefully touch up an enormous mural covering an entire wall of a Philadelphia parking lot.
"At first, I was afraid of heights, but I'm not anymore. Now I actually love it," Saligman said from her perch where she worked on refurbishing the 500-square-meter (nearly 5,400-square-foot) painting.
Philadelphia, located midway between New York and Washington on the US East Coast, has a staggering 3,800 enormous works of wall art, from the historic district to the more rough-and-tumble neighborhoods on the city's outskirts.
Some of the massive paintings in the city's Mural Arts Program -- the largest public art program in the United States -- feature scenes from daily life, while others offer colorful renderings of abstract themes.
On one abandoned building, there is a giant portrait of basketball great Julius Erving. Another has a profile in various shades of blue of singing legend Frank Sinatra, sporting his trademark fedora.
Program director Jane Golden says the initiative had rather humble beginnings.
"It actually started as an anti-graffiti program in the mid-1980s," she told AFP, explaining that the huge paintings were a way "to re-channel the negative energy" of Philadelphia's impoverished neighborhoods.
The goal was to beautify the cityscape, she explained, as well as to help the city's youth broaden their view of themselves.
"It wasn't just about painting out the graffiti," Golden said.
"It was about working with kids who had been doing graffiti... providing them with opportunities and options to think of themselves as artists, and then to think about what other opportunities there were for them."
Three decades after its founding, the Mural Arts Program now hires some 200 artists each year -- some to restore or paint murals, others to give classes.
The program has an annual budget of some $6.5 million -- about 30 percent of which comes from city coffers, but most of which comes from donations or the sale of souvenirs.
And it has more work than ever because some of the older murals have lost their luster over the years. That prompted the program to launch a restoration program about a year and a half ago.
"The red has completely faded into green," Saligman observed, standing before a mural wall that once had been a glorious riot of colors when it was first painted in 1999.
"We used a paint that didn't last," she explained.
Meanwhile, new murals financed by the program are created by individual artists, each tending to his own studio and creating the works with the assistance of other artists.
The images in some instance are painted directly onto a building wall. But another technique that allows the artists to work indoors and year round has them apply paint to swatches of parachute cloth which later are adhered to the wall in sections.
"It's basically wallpaper," said Ernel Martinez, his sunglasses perched atop his head, as he helped to install the first sections of another mural dedicated to the popular music group "The Roots," whose members are from Philly.
Some of these murals are produced in part by Philadelphia's disadvantaged youth, some of whom are fresh out of prison.
"We're all 10-12 years older -- we are sort of mentors for them," Martinez said. "It's a really interesting interaction."
The wall of another workshop run by artist Jon Laidacker is completely covered with six such lengths of fabric, each about one square meter in size.
"Right now, you're looking at a giant lemon and parts of carrots," says Laidacker, the lead artist, describing his work "Cornucopia" -- a giant mural depicting fruits and vegetables.
Once assembled, it will be impossible to tell that it was not actually directly painted onto the building.
Golden sees the involvement by local residents as one of the program's greatest successes.
The fact that only a very small number of the works have ever been defaced, she said, shows the degree to which Philadelphia residents have bought into the popular art project.
"The benefit to the city is huge," she said. "It is known as a city that cares about its communities, that cares about its youth."