Street art superstar JR has unveiled his newest project in an unlikely location: atop a maximum-security prison in Southern California.

Named Tehachapi after the town two hours north of Los Angeles where the prison is located, JR’s installation depicts 48 current and former inmates looking upward in a composited collage. The monumental artwork is only visible from above—or through an app, where viewers can tap on each incarcerated person in the digitized picture and hear their stories told in their own words. 

A friend approached the artist this fall with the idea of bringing his vision to a California correctional facility. “A friend of mine asked me if I wanted to do something at this prison,” the artist told Artnet News, noting that many of the “inmates were incarcerated when they were kids—14,15” and will be in there “for life.”

“Most of them haven’t killed anybody, they’re there because they had three strikes. I steal your phone, I steal your car, and one felony, and I get life,” JR said. “Now they’ve changed that law, but those guys are still stuck in there.”

Composed of 338 strips of paper, Tehachapi boasts a footprint similar to JR’s Louvre project from earlier this year, which spanned some 183,000 square feet. This work was installed by the subjects of the photo—including former inmates who returned to the facility for the first time since being released—along with prison staff and JR’s team. The process took only a few hours. The final photograph of the work was taken from above by a drone. 

Through the artist’s custom app, JR Murals, users can explore the image and the stories behind the people in it. “I made a mistake when I was a child,” explains one current inmate, an ex-gang member. “I was 21 years old when I committed my crime; I’m 37 years old now. Every day I strive to become a better person. People out there have this perception of people in prison, that we’re not able to rehabilitate… It’s a reservoir of people that can contribute.”

This is the fourth monumental multimedia piece JR has created for the app, which is available for free. He debuted the form for a special report in TIME Magazine on gun violence in America last year, then followed it up with two massive interactive murals for his solo exhibitions at the Brooklyn Museum and San Francisco Museum of Modern Art, both of which aimed to offer interactive portraits of residents in their respective cities.

For Tehachapi, JR explains, the form gave a voice to those locked in a system that does not otherwise offer them one. “Who are the kinds of people who are in there?” the artist asks rhetorically. “I don’t make any judgments. I just listen to their story. Some spoke for 10 minutes, some spoke for 35. It was difficult but we met amazing people.”