For 27 years around Halloween, Eastern State Penitentiary has brewed up one of the most horrifying immersion experiences in the country. Though classified as a haunted house, the label is almost a disservice to the elaborate nature of this one-acre attraction that’s more interactive theater than your typical spooks-filled farmhouse. Terror Behind the Walls involves six segments that add up to about an hour’s worth of character interaction, bone-chilling scares, prison exploration and elaborate costuming and makeup. Visitors can opt to wear a glow necklace as they wander through the facility’s dark confines, signifying that actors are welcome to speak with or touch them. From there, episodes follow a loose script, always driven by storylines with actors encouraged to indulge in improv and audience interplay. This year’s brand-new attraction, “Blood Yard,” posits what it might be like to prepare human flesh for the tasting. Guests walk through a prison yard into a lair where a butcher and an empress await, flanked by a horde of cannibals wearing muzzles. Those who choose to interact could be asked to salt and prepare prosthetic limbs alongside the impatient flesh-hungry characters.