For the 22nd year in a row, the Eastern State Penitentiary's "Terror Behind the Walls" is scaring thousands of visitors during Halloween season as they embark on a frightening tour around the abandonned prison.

But what really goes on behind closed doors of the historic penitentiary, which has become the largest haunted house in the country outside of a theme park? Some staff members weigh in.

Before the prison doors open each night of Halloween season, it takes several hours of make-up, meetings, and warm-up activities to get the actors prepped to scare visitors as they take a terrifying 45-minute walk through the prison where some of America's most notorious criminals once stayed.

Nickki DuBan, one of the 14 make-up artists who work each night to get about 200 actors ready – including prison guards, zombies, clowns, and nurses – says she and the make-up crew have a little less than three hours to get everyone ready to start scaring.

"It's really high-energy," DuBan says of the work atmosphere. "It's very, very fast-paced, just trying to get everybody in and out as fast as possible, but also to kind of keep that pumped up feeling going."

Make-up can take anywhere from three minutes to 45 minutes per actor. One of the actors whose make-up takes the most time is a character with a chainsaw. This process is a little more extensive because it includes a prosthetic, which was molded over the summer, as well as special paint.

"His face looks like it was cut through with the chainsaw," DuBan says. "Sometimes you have to cut and manipulate the prosthetic, which can take a while."

DuBan, who has been working at the popular Halloween attraction for eight years and works at year-round as a digital operations lead, says none of the characters she creates scares her, except for one: the clown.

"As I'm doing his make-up, I'm fine, but as soon as I put in all the detail and start whiting out the area on his face and I see that he's turning into a clown, it weirds me out," she says.

The clown is in a special 3-D part of the attraction, so his face requires a different type of make-up – neon colors that are water-based – to make it look like his eyes and mouth are popping out.

DuBan, who started working with make-up while attending La Salle University, says she enjoys this job mostly because "it's not normal," and that she gets to meet new people every year.

"It's not your every day run-of-the-mill 9-5 kind of job, and it gives you creative freedom," she says. "I also really like that it serves a purpose. 'Terror' is a fundraiser for Eastern State Penitentiary – it's a national historic landmark – so the work that we do here directly benefits preservation of property. Not only is it a fun job but you're also doing good."

Along with the make-up artists, there are creative directors, line staff, event staff, among other jobs, which have to be auditioned for year after year.

Casey Conan, who is both an actress and the manager of Detritus (one of the six attractions in "Terror"), says seeing the reaction of the visitors is "the best part of my day."

"It goes from absolute terror and primal fear to laugher which is how I know everyone's having a good time," she says. "If I get a scream and then a laugh I know I did my job right."

Conan, who is in her fifth season at the haunted house, wears a leather belt and navy skin that has bones and pieces of hair attached to her to make it look like she's a tribal character running through a forest. She pops out throughout the attraction and makes a unique chirping noise to scare the visitors.

Her costume goes along with the theme of Detritus, which she says "is based on the idea of rot and decay, and the garden has been left to fend for itself."

The actors in this part of the attraction include characters with chainsaws, bushes that come to life, and wild children.

"We like to bring our guests to our garden and keep them there for a while," Conan says.

This year is the first time "Terror Behind the Walls" allows actors to touch the guests. The visitors just have to mark their cheek and wear a tracking device if they would like to be touched.

"We wanted to make this year darker, bloodier; terror that you never felt," Conan says. "The creative team came up with a very interesting and unique way to make it a more intense experience while maintaining that classic haunted house feel we've always had here."

Conan is one of the actors who interacts with the visitors. She says she picks out the visitors and brings them into an interrogation room before returning them to their friends.

As a manager, Conan's duties include scheduling, making sure all of the actors get two breaks in each shift, and making sure the interactions are safe.

She says before each shift she'll run a meeting where they'll do warm-ups, stretch, and play improv games.

"It's a lot of community building," she says. "We have to be together for a long period of time so we really want to make sure everyone feels like a family and we can all count on each other."

Although Conan is in the prison for 5-8 hours at a time, she says the only time she gets remotely scared is when all of the visitors are gone.

She says the most interesting thing she finds about her job is just being in the historic building, with its castle-like walls and decaying cellblocks.

"The building is massive and it's got a personality of its own," she says. "It's as much as a part of the show as any of us are."

There are 29 shows this season, with the last one on Nov. 9.

For more information about the attraction, visit