PHILADELPHIA — Built as a punishing fortress in 1829, Eastern State Penitentiary sat a mile and a half outside Philadelphia, isolated behind 30-foot walls, a model of solitary confinement imitated around the world.

The prison remained in use for the next 142 years, even as Philadelphia grew around it. It closed in 1971; then the site was rescued in the 1980s and stabilized, preserved in a permanent state of decay. Today, the brick and stone of the vaulted ceilings are crumbling. Layers of paint are flaking off the walls, and floors are heaped with dirt and dust. Inside the cells, beds and tables are toppled, drawers ajar, frozen in time.

The building once attracted more visitors than Independence Hall, even as its practices drew critics including Charles Dickens, who called the prison a place of “torture and agony.”

“People feel a power being in a real place that has historic significance,” said Laura Lott, president and chief executive of the American Alliance of Museums.

Although it no longer outranks Independence Hall, hundreds of thousands of visitors come each year to explore its grounds, accompanied by an audio tour narrated by actor Steve Buscemi.

But recently talking about the site’s history didn’t seem like enough for Sean Kelley, senior vice president and director of interpretation. Two years ago, after discussions about how the museum addressed the rising number of people incarcerated in the United States — especially people of color — Kelley helped rewrite the museum’s mission statement, declaring that Eastern State would no longer be neutral in recognizing mass incarceration as a crisis.

“Eastern State Penitentiary’s move in this way seemed really courageous because it was not just presenting multiple viewpoints, but taking a stand on the issue,” Lott said.

Marney Penn, a tour guide for the museum, said that it was important to integrate discussions about modern incarceration into the museum’s story since Eastern State helped make the prison system what it is today.

“Sometimes you do need to shock people to attention,” Penn said. “If you’re coming here for a historic tour, that’s great. But at the end of your tour, it’s like, surprise, we have all this really serious information for you.”

Art installations in the cells have long been a feature. There are also family weekends with a program that works with inmates to train shelter dogs; visitors can meet the dogs and learn about “Pep,” Eastern State’s famous canine “prisoner.” There have been on-site tastings of Nutraloaf, a composite food product served in prisons.

Since 2012, Eastern State has marked Martin Luther King Jr. Day by hosting readings of King’s “Letter from Birmingham Jail” in its historic synagogue.

You could easily take the tour, peer into the cell where Al Capone stayed for a few months in 1929 and leave, Kelley said. That might be all visitors want to see, and that’s OK.

But it’s hard to miss the 16-foot “Big Graph” sculpture in the prison yard at the end of the tour. It illustrates the number of people incarcerated in the United States over the decades on one side, with the racial breakdown on the other.

From there, it’s a short walk to “Prisons Today,” an exhibit that opened in 2016 and was honored by the Alliance of American Museums. Learn about different forms of incarceration around the world and how your upbringing might affect your chances of going to prison. In an interactive display you can read confessions by both visitors and imprisoned people.

The capstone is a video installation produced by Greenhouse Media using archival video and C-SPAN clips that charts the prison population over the decades and the political response to mass incarceration.

“They are a leading organization among historic sites,” Paula Marincola, executive director of the Pew Center for Arts and Heritage, said. “They do very thoughtful and imaginative work in interpreting their site for their public and connecting the site and its history to contemporary issues.”

The Pew Center has supported Eastern State on a number of initiatives, including one currently in the works. No longer content to just talk about the modern prison system, Eastern State is going inside.

It started when Kelley took a trip to Chicago and saw a screening of “Freedom/Time,” a work artist Damon Locks created with inmates at Stateville Correctional Center in Illinois, using frame-by-frame animations on tracing paper to tell eight-second stories.

“I came back here, and I couldn’t stop thinking about it,” Kelley said. “I couldn’t stop thinking about that quote that prison walls don’t just keep the prisoners in, they keep the public out.”

Sitting in the coffeehouse across the street, he looked at Eastern State’s walls and saw an opportunity to bridge the divide.

“Hidden Lives Illuminated,” a collection of one-minute films made by people in Philadelphia-area prisons, will premiere in August and be projected onto those walls. Among the stories: The 18 dogs one man has fostered while in prison; the musical prodigy son using his music to cope without his father; the loneliness of a 22-year-old fighting cancer while in a cell.

“We’re trying to let the voices of people who are incarcerated be a springboard for deeper conversations about criminal justice reform,” Kelley said.

The scale will be hard to ignore. In December, while testing the projector by showing a film on the walls, “people were coming out of the coffee shop and clapping, cars were slowing down, people walking their dogs were like, ‘What are you guys doing?'” he said.

Three years ago, the museum began hiring former inmates — referred to as “returning citizens” — to work as guides. He said that museum officials kept feeling like they were “at this arm’s length talking about groups of people.”

It isn’t required that the guides talk about their experiences, but choosing to can be enlightening for visitors.

In the exhibition “Prisons Today,” display boxes hold items belonging to some of those guides. Recently, Penn struck up a conversation with two women examining commissary receipts inside one box.

Those were her receipts, she told them. Penn’s experiences help her explain things in a way other guides can’t, including how she bought necessities, like deodorant, while earning only 19 cents an hour.

“We hold onto things, we are opinionated, and there is stigma attached with criminals and people who come out of the criminal justice system,” Penn said. “I love my job because we break down those barriers.”

This article originally appeared in The New York Times.