(CNN) — We wouldn't go in there either.
For National Geographic's Asia TV series, "I Wouldn't Go in There," urban explorer and blogger Robert Joe went investigating Asia's scariest places, country by country.
"People might think it's a ghost show, but it's actually a history show," says Joe.
"Asia has been embroiled in so much turmoil in the past 100 years, and is only just getting out of it now.
"We investigate places that have ghost stories, but these places are actually haunted by history. A lot of terrible things happened."
Abandoned Taiwanese jails for political prisoners, caves where Japanese soldiers killed themselves en masse after World War II, a South Korean haunted house on a hill where soldiers from a failed beach landing were supposed to have been buried ...
It's Joe's job to start with rumors and uncover the real history that often turns out to be more gruesome than any spook story.
CNN: How did you pick which places to go?
Inside South Korea's most famous haunted house.
Robert Joe: We used the strength of the initial stories of hauntings as a jumping off point. Obviously, strong visuals were important.
Vivid stories of dead soldiers or women spirits in red, haunting some old abandoned mansion or school, were perfect to explore.
We also had to consider the strength of the story in the local population, how popular the legends are, how old.
And finally, we wanted stories that really lead us to some meaty historical revelation. That's where we hit a lot of dead ends so to speak. Not every story pans out. Not every place turns out to be promising.
CNN: What are the scariest things you encountered?
Robert Joe: Other than the locations, we'd meet spiritual figures or practitioners.
Sometimes these people could be quite alarming in appearance, and the things they say or did would be really over the top and unpredictable.
That could be scary. But other times it was also hilarious.
CNN: Which places were scariest?
Robert Joe, fearless urban explorer.
Robert Joe: The locations themselves were quite foreboding. Dark, derelict, genuinely dangerous -- holes to fall to your death.
And for realism we often went late at night, with a skeleton crew.
So we'd be going through these places that are closed off, but you do hear weird noises and your mind can play tricks on you.
In Okinawa, in this massive abandoned hotel, we were exploring some room and we heard distinct knocking sounds coming from just outside.
No one wanted to go, but of course we had to go explore.
We turned the corner and there was just this lone figure in the shadows pointing a light at us. No one moved. It turned out to be another team of urban explorers.
CNN: Can anyone visit these places?
Robert Joe: Most of these places aren't open to the public. A lot of them for very good reasons; they're not structurally sound or they're private property and the owners don't want to be associated with supernatural hauntings.
But some of them are accessible to the public as historical locales and welcome visitors.
I guess every place is accessible if you're determined enough, but it's not something I'd consider safe or could recommend.
CNN: What else did you find interesting?
Robert Joe: It was interesting to see how people sort of compete to be associated with certain local legends.
They like to be known as the authority when it comes to this or that story or this or that haunted location.