I worked construction on New York City’s mysterious windowless building – here’s what I saw

Nestled in the heart of lower Manhattan, the mysterious 33 Thomas Street, commonly known as the ‘Windowless Building’, has remained shrouded in secrecy for decades. 

This formidable skyscraper, devoid of windows and rising 550 feet into the skyline, has puzzled New Yorkers and intrigued passersby since its completion in 1974. 

Often regarded as one of the city’s oddest buildings, its true purpose has long been a subject of intrigue and speculation.

One man, who chose to remain anonymous for safety reasons, worked as a steamfitter – someone responsible for installing wiring and pipes carrying liquids and gases under high pressure – in the building with his son back in the early 2000’s. 

His son told Dailymail.com his father and crew were strictly forbidden to enter certain rooms in the building. There were off-limit areas of the building that were restricted for all visitors. No one was allowed to enter. 

‘There were rooms we couldn’t get into. They specifically told us not to enter, and we couldn’t ask what’s inside or why we can’t go in,’ he said.  

The crew ultimately ended up having to install wires around the rooms, an unprecedented move in the field of steam fitting.  

Additionally, the crew once found what appeared to be confidential papers in a filing cabinet in the basement of the building. 

The classified information was regarding what to do with machines in case of a radiation attack. 

Since being built the windowless building functioned as AT&T’s long-distance telephone exchange until 1999, when the company moved elsewhere. 

Today, the windowless skyscraper is still sometimes used for its original purpose of telephone switching by some local exchange carriers.

Other areas of the building are reportedly used as a high security datacenter. 

It’s now more commonly known as 33 Thomas Street, rather than the AT&T building or the Long Lines Building. 

Constructed under a cloak of secrecy, 33 Thomas Street was designed to withstand an atomic blast, according to an exclusive report about the building by The Intercept in 2016. 

Keep reading