Terror Behind the Walls, Philadelphia, Pennsylvania
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The Most Terrifying Haunted Houses in America

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Terror Behind the Walls, Philadelphia, Pennsylvania
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Beyond Spooky

You could always put on some scary face paint and celebrate Halloween with some mild, even family-friendly spookiness at a theme park or throw on one of this year's most popular Halloween costumes to take part in frightfully fun Halloween parades and festivities happening across the country. But maybe that's not scary enough for you. Here are some haunted houses that are so terrifying and physically demanding participants have to sign waivers before entering. Don't say you haven't been warned.

Related: The 25 Most Terrifying Places in America

Blackout, New York
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Blackout | New York City

Blackout is one of the originators of the extreme haunted house. It's been in L.A. and San Francisco, but this year returns to New York as a full-contact experience for one guest at a time. Participants may be restrained, aggressively touched, made to crawl or kneel, all while immersed in violent or sexual imagery. There is a safe word that guests can yell if they want out of the experience, but there are no refunds if they use it.

Castle of Chaos, Midvale, Utah
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Castle of Chaos | Midvale, Utah

Castle of Chaos allows participants to choose from five levels of fear. At the lowest level, monsters are repelled by your glow stick. But at the highest, they may pick you up, drag you through doorways, or restrain you. For those who crave the most hardcore of haunts, they offer Krusebel, an extreme, hours-long experience that combines both physical and psychological torments.

17th Door, Fullerton, California
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17th Door | Fullerton, California

17th Door follows the ongoing story of Paula, a college student-turned-murderer now imprisoned in a treacherous penitentiary. As her fellow inmates, guests will wind through the maze in an attempt to unlock the story and escape unscathed. Previous shows have involved real cockroaches, being smothered in a ball pit, lots of touching by handsy actors, and virtual reality add-ons. Guests who can no longer endure the experience can yell "Mercy" to escape.

Scarehouse: The Basement, Pittsburgh, Pennsylvania
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Scarehouse: The Basement | Pittsburgh

You can either enter this Pittsburgh attraction alone or with one companion, but that's it. Guests must sign a waiver before encountering narrow spaces, complete darkness, and "high impact scares." This haunt is made by a group of dedicated artists and counts horror enthusiasts Elijah Wood and Guillermo del Toro among its fans. Scarehouse also offers Stalked by a Killer, a horror-themed escape room.

McKamey Manor, Alabama & Tennessee
McKamey Manor

McKamey Manor | Summertown, Tennessee and Huntsville, Alabama

It's almost unfair to call McKamey Manor a haunted house, as this extreme torture session goes far beyond what most haunters feel comfortable doing. Participants must have physical and mental clearance, plus sign a 40-page waiver in advance. After signing, they'll face mental torture Russ McKamey says he honed from decades conducting interrogations in the military. He promises $20,000 to anyone who can last the full 10 hours, but no one's ever done it. The price of admission? A donation, preferably a large bag of dog food. While McKamey says the original website has been hacked, all the information needed to attend is on YouTube — including hours of footage of people admitting defeat.

Related: The 20 Most Haunted Hotels in America

Terror Behind the Walls, Philadelphia, Pennsylvania
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Terror Behind the Walls | Philadelphia

Terror Behind the Walls takes place at Pennsylvania's supposedly-haunted Eastern State Penitentiary. This sprawling haunted house allows you to make a choice: enjoy a hands-off tour or spring for full interactivity. Those who choose the latter may be touched, singled out and removed from their friends, or taken into secret areas. Guests are warned that once the choice is made, they'll have to "deal with the consequences of their decision through six long attractions."

Miasma, Chicago, Illinois
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Miasma | Chicago

Chicago's Miasma is an invite- and adults-only interactive haunt where warnings include "aggressive physical contact," "clothing removal and/or destruction," "crawling on hard surfaces," and "graphic adult content," among others. Though they have a variety of shows throughout the year, anyone feeling particularly brave can request a private experience with a unique, tailored narrative.

The 13th Gate, Baton Rouge, Louisiana
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The 13th Gate | Baton Rouge, Louisiana

If Indiana Jones ever found himself in Baton Rouge, he would not want to do this haunt, which boasts of its "real, snake-infested Louisiana swamp." The 13th Gate is a massive, top-rated haunt for thrill-seekers, featuring incredibly detailed sets and awe-inspiring effects that elevate themes and stories year each year. On Fridays, you can brave a lights-out maze with just a flashlight.

Shock Theater, New York
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Shock Theater | Hauppage, New York

Shock Theater specializes in intimate, story-driven haunts, each with a different theme and associated terrors. A previous Valentine's show had two guests at a time show up for a "blind date," during which they were blindfolded, grabbed and otherwise tormented in the quest for true love. In another, guests acted as models for two artists who wanted to capture the most authentic expressions possible, even if that meant resorting to torture to get them.

Zoe, Fullerton, California
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Zoe | Fullerton, California

In Escapade Game's Zoe, players are locked in a haunted house with the ghost of a young girl. To get out, they must solve a series of puzzles before their time runs out. So not only are you scared, you have to think, too. Things are not always what they appear in Zoe, and its detailed, creepy environment has inspired many seasoned reviewers to claim it's the scariest escape room they've ever played.

The Fear Experiment, Danville, Illinois
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The Fear Experiment | Danville, Illinois

The Fear Experiment is an immersive, psychological horror experience. The experience is for adults only, who will sign a waiver and receive a safe word. Though the experiment warns of physical contact, discomfort, aggression, and nudity, they also promise to "allow you to push your limits, test yourself, and find out what you're really made of." What that means is unclear, as all participants are instructed to never share spoilers online or in-person.