Thread by @bbcstories

There’s no lift button for the 5th floor at Pyongyang’s Yanggakdo Hotel - and visitors are told to stay away.

We spoke to a man who's been there.

bbc.in/2M2Dzqv

In 2011 Calvin Sun was on a packaged tour of North Korea when he noticed something on the lift panel of the Yanggakdo Hotel.

There was no button for the 5th Floor.

Travellers had long spoken of the mysterious floor – but in 2011 there was no warning to not go there.

"We weren't the first group to go to the fifth floor - or the last" Calvin says. “The weight of what we were doing didn't occur to us."

Calvin and his friends got off on the 4th floor to approach the fifth floor through the stairwell. One of Calvin’s friends heard screaming, so they changed direction.

When they got to the fifth floor via the stairwell down from the sixth, they were surprised to find it was unmanned.

Stepping inside they found the ceilings were half the height of the other hotel floors, with many propaganda posters on the wall.

There was a floor within a floor, and door that opened to a brick wall.

One room had TV screens which showed the inside of the hotel rooms.

“I now began to think that this floor was where the hotel staff reportedly kept equipment to surveil guests" Calvin says.

As Calvin and his friends were preparing to leave the hotel, North Korean guards approached them.

They said they knew what one member in the group had done and they should confess now. The group remained silent.

To Calvin’s relief the guards weren’t talking about their trip to the 5th floor, but about a missing towel they claimed was stolen from the hotel.

Luckily, the group's tour guides helped diffuse the situation, and ensure they got out of the country.

For four years Calvin rarely thought of the fifth floor – until he heard about Otto Warmbier, who was detained by North Korean officials in 2015 after staying at the Yanggakdo Hotel, accused of attempting to steal a North Korean poster.

Warmbier was subjected to a sham trial and then a forced TV confession.

Convicted and sentenced to 15 years hard labour, he sustained injuries while incarcerated and he fell into a coma from which he would not regain consciousness.

Otto Warmbier died a year ago today.

Calvin says: "I feel terrible about what happened to Otto. And knowing what we now know, I would certainly advise all travellers to respect the customs of the country they are visiting."

Picture credit: Reuters