Josh Gates has traveled across the world in search of evidence of the afterlife, but there is one place he never wants to visit again.

“I would say Waverly Hills, which is an abandoned sanitarium here in the States — it’s high on the list of places I don’t ever want to spend the night again,” the TV host told Fox News when asked to list the scariest place he’s ever been to in America.

“A lot of those old, 19th-century sanitariums, mental institutions, there are a number of them left here, old prisons, things like that,” he said. Eastern State Penitentiary… They’re really, really spooky. I don’t care if you believe in ghosts at all. I challenge you to go spend the night walking the halls of Waverly Hills in Kentucky, which is a terrifying place.”

The 41-year-old is the host of Discovery Channel’s “Expedition Unknown: Search for the Afterlife,” where he attempts to seek evidence of the great beyond. For the series, he attended an exorcism, met scientists to explore the moment after we die, visited a haunted ship and headed to Varanasi, India to learn more about their rituals to help people’s spirits pass over, among other things.

The Waverly Hills Sanatorium in Louisville, Ky., is pictured on Monday, Oct. 21, 2013. The vacant building has become an attraction for ghost hunters and paranormal enthusiasts, who insist the building is haunted by former patients.

The Waverly Hills Sanatorium in Louisville, Ky., is pictured on Monday, Oct. 21, 2013. The vacant building has become an attraction for ghost hunters and paranormal enthusiasts, who insist the building is haunted by former patients.

Immediately following the finale, Discovery will air “Expedition Unknown: After the Search," in which Gates will lead a detailed discussion with his crew and guest experts on the subjects explored in the series, as well as analyze footage never seen before.

Gates, who was raised an Episcopalian, said his experience filming the show has challenged his beliefs.

“In the first episode, I openly stated that I was raised Christian,” he explained. “And like a lot of people, I sort of drifted away from the church as I got older. Now I have two small kids. I have a family and I’m starting to ask those questions. I’m at a point in my life where I’m saying, ‘What is really out there?’ For me, there were a number of moments in the special that really challenged my agnostic beliefs.”

For “Expedition Unknown,” Gates even traveled into the Amazon to experience ayahuasca or the “vine of death.” It is said the hallucinogenic brew connects people to the spirit realm.

Ayahuasca is a traditional and very powerful hallucinogenic brew made from the root of a local jungle vine. 

Ayahuasca is a traditional and very powerful hallucinogenic brew made from the root of a local jungle vine.  (Getty)

Gates had no idea what awaited him.

“It was a really challenging experience for me, certainly not something that I was used to doing,” he admitted. “But I really wanted to understand whether this is something that can connect you to the other side. It’s a really potent hallucinogen, and it was a very intense experience. And I tried to lay as much of that bare in the show as I could… you’ll see exactly what the effects of it [were], which as I said, can be profound at times, but also really uncomfortable.”

Gates is aware some viewers may scoff at his quest and insists his findings of potential ghost activity are nothing more than clever editing. Still, he welcomes critics to tune in to decide for themselves.

“Most cultures believe, and most religions believe, that there is a spirit, there is a soul, there is something that happens when we die where this spirit leaves our body,” he said. “And there are people all over the world who believe in ghosts and angels and demons — things like that. And we touch on this throughout the show. But belief and faith are very personal things.”

And if there’s one place in America Gates would encourage viewers to visit to have their own paranormal experience, it’s in the infamous Queen Mary, a luxury art deco ocean liner involved in several tragic events.

“It was involved in a terrible accident where it actually rammed and sliced into its escort ship called the Curacoa, and hundreds of men died in the water from that accident,” said Gates. “We know that many people died aboard the ship. … Most people who believe in ghosts ascribe to this idea that ghosts tend to congregate, or exist, in places where death and tragedy have occurred, and the Queen Mary has certainly seen its share of tragedy, and its share of history.”

The Queen Mary, which is open to the public in Long Beach, Calif., is reportedly one of the most haunted places in America. Gates said many visitors claimed to have experienced some unusual encounters during their time there.

“There’s a woman that they say appears in the Queen’s salon that people have described very consistently, over and over again,” said Gates. “They describe a sailor in a certain part of the engine room who appears in this doorway where a sailor was, in fact, crushed to death.

Queen Mary

Queen Mary (Getty)

“You have these accounts that continue to come forward, and that’s why paranormal investigators… like to focus on places like the Queen Mary. It’s because of those paranormal accounts. The question is, do you believe that those accounts are real, or are they people’s imaginations? And that’s what the segment is all about, is trying to collect real evidence of the paranormal.”

"Expedition Unknown" airs Sunday at 10 p.m. on Discovery Channel.