In the middle of New York City, there is a 29-storey building that has no windows and is shrouded in mystery - but what actually goes on in there?
It’s called the Long Lines Building, and it has many people wondering about its purpose.
Even Hollywood star Tom Hanks called it the ‘scariest building I’ve ever seen’.
The Long Lines Building is a windowless skyscraper wrapped in mystery
The building itself is seriously imposing - concrete walls, no windows to speak of, and rising tall out of the streets of one of the world’s biggest and busiest cities.
It is 550 feet tall and sits in the Manhattan skyline at 33 Thomas Street.
Speculation has surrounded the building for years, with social media photos circulating showing the imposing and somehow impressive building.
Captions read like ‘a 29-storey building in NYC with no windows’ and pose questions like ‘what goes on in here?’
It has even captured the imagination of Hollywood royalty Tom Hanks, who posted: “This is the scariest building I've ever seen! WTF happens inside?”
WTF indeed, Tom.
Well, it gets weirder from there, too.
According to documents seen by US-based media company The Intercept, the building has a National Security Agency codename - TITANPOINTE.
Those documents, which were obtained by NSA whistleblower Edward Snowden, suggest the building is a secret NSA surveillance site.
Whether that is true or not, we’ll have to keep wondering.
So, what do we know about this unusual New York landmark?
We know it’s called the Long Lines Building, and it is built as if to stand a blast from a nuclear warhead.
However, it was originally built to protect something non-human - lines of communication.
It was home to one of the most important telecommunications hubs in America, and it is built to protect the switchboards, computers, and cables within.
It was operated by the New York Telephone Company, which is a subsidiary or AT&T.
At one stage it was the world’s largest center for long-distance call processing.
So, it was important.
Designed by architects John Carl Warnecke & Associates, the building was designed windowless, with 29 floors above ground and three basements.
It has space to store enough food to keep 1,500 people alive for two weeks in the event of a serious disaster.
Finished in 1974 after five years, the building has been the subject of some crazy rumors, from Men in Black to vampires.
One tweet about the building reads: "Lizard people don't need windows."
To be fair to the lizard people, if they are anything like real lizards, they'll need sunlight to warm their blood, but we digress.
Still, it’s a creepy-looking building, which once played a seriously important role.
Maybe it still does, depending on how true those NSA documents are.