Man who worked on New York's mysterious windowless skyscraper reveals what he saw inside

Among all the shiny, glass skyscrapers of New York City, there’s one building that stands out for a very different reason.

Not for what you can see inside, but for what you can’t.

At 33 Thomas Street, there's a behemoth of a concrete tower.

Besides the entrance on the ground floor, there are no windows anywhere on this massive structure.

For years, people have long wondered what could be kept behind the walls of the eerie building built in 1974.

Even actor Tom Hanks was freaked out when he walked passed by a few years ago.

'This is the scariest building I've ever seen! WTF goes on inside?' he tweeted back in 2017.

Roy Rochlin / Contributor / Getty

One man who had the rare chance to go inside spoke to the Daily Mail under the condition of anonymity about what he saw when he was hired for a job there in the early 2000s.

The man and his son said they weren’t allowed into certain areas of the building and some parts were strictly off-limits to all visitors.

I mean, lots of buildings have restricted areas.

But more suspiciously, the man and his son 'couldn't ask what's inside or why we couldn't go in' or why certain areas were forbidden.

Naturally, when you're not allowed to ask questions, it makes you wonder if there's some shady government or CIA stuff going on.

What they did come across though, were documents outlining what to do with certain machines in case of nuclear fallout.

As it turns out, the building can apparently be self-sufficient for two weeks during a nuclear disaster with enough supplies to take care of 1,500 people.

Roy Rochlin / Contributor / Getty

The official story is that 33 Thomas Street was built to house phone-switching equipment and was originally called the AT&T Long Lines Building. Basically, it connected long-distance phone calls.

Previously, TikToker Eric Guidry shared the not-so-eery purpose of the building: "So that building in New York, this windowless building in San Francisco, this one in Chicago, this one in Austin and hundreds more buildings placed conspicuously across the country, in very populous locations."

Still, that hasn’t stopped a few conspiracy theories from floating around like what Area 51 experiments might be going on in there.

Unfortunately, the real reason behind the windowless design isn’t as exciting as you might think.

Turns out, it's not about hiding anything (apparently) but more so because no one inside needs windows in the first place.