Eastern State Penitentiary’s annual gore fest is back: “Terror Behind the Walls” opens September 21 for six weeks of blood-curdling fun.

The former prison, which opened in 1829, once held some of the country’s most famous criminals — including Al Capone and “Slick Willie” Sutton. Each Halloween season, the already creepy building is transormed into a haunted house to educate and entertain people around the world.

“Terror Behind the Walls,” now in its 27th season, is actually a fundraiser to help preserve the historic site and fund year-round educational programs. Visitors can take daytime guided audio tours narrated by Steve Buscemi every day of the year from 10 am — 5 pm, but every fall, visitors can come at night to get scared at the self-proclaimed “Halloween Destination.”

Amy Hollaman, creative director of “Terror Behind the Walls,” said it’s is a perfect Halloween experience for families. “We’ve designed the show because whether you’re a child, adult, or parent, you can design your scare your own way. So you can say how scary you want it to be.”

This year’s new attraction is Blood Yard, which is the third of six attractions included with admission. Set within the ruins of the prison, a bone-marked path leads visitors through the lairs of the butcher, warriors, and ancient empress, where you’ll learn about the back stories of the characters while avoiding the haunted beings that roam the prison grounds.

The other five attractions are Lockdown, Machine Shop, Infirmary, Quarantine, and Breakout. In Infirmary, some visitors will receive a virus, and Quarantine is a 4D experience with UV blacklight, and ChromaDepth 3D glasses.

Visitors can opt in to an interactive experience, which is certainly not for the faint at heart. Guest wear a tracking device (aka a glow necklace) that signals to actors that they can be touched and possibly even taken. However, this is completely optional, and you’ll still get the shock value without being touched.

If you’re still scared, there’s another layer of protection against the monsters: saying “Monster, be good!” fends off all of the creatures that come towards you.

“It feels like you’re heroes when you’re bonding together in this safe space to be scared, but the whole time you know it’s pretend,” Hollaman said. “Families can feel like they did it together and they survived, sometimes saying it every step of the way. It’s almost like they have special powers against the monsters coming towards them.”

Hollaman said visitors from around the country and around the world have made a whole day centered around Eastern State, starting with the daytime tour, then dinner at some of the awesome restaurants in the Fairmount neighborhood, and finally the nighttime scares. After this many years, she said, there’s been a focus on making the experience enriching for families.

“What’s really neat for families is that they get to step inside of history. It’s not just opening up a textbook and looking at a sign on a wall,” Hollaman said. “It helps kids think back in time about what it was like in prisons. It’s a great experience for families to come and talk about some of these hard questions that wouldn’t come up every day around the dinner table.”

That said, it’s a scary attraction and is probably best for older children and teens — as well as brave adults.

“Terror Behind the Walls” runs from September 21 through November 10 on select nights. Tickets start at $19, but vary per night. for more information, visit the penitentiary’s website.

Photographs by Casey Kallen.