The windowless skyscraper on Thomas Street in New York City is shrouded in a bit of mystery, but here’s what we know:

The Building: Officially called 33 Thomas Street, it’s a 550-foot (170-meter) tall Brutalist style skyscraper built in 1974. Its most striking feature is the complete lack of windows on its exterior.

Original Purpose: 33 Thomas Street was originally built for AT&T as a long-distance telephone exchange. It housed switching equipment that required a tightly controlled environment, hence the lack of windows. The windowless skyscraper design also offered structural stability and some believed it could withstand a nuclear blast.

Current Uses: While AT&T moved out in 1999, parts of the building are still used for telecommunications purposes by other companies. Rumors suggest some areas function as high-security data centers.

The NSA Connection: Here’s where the mystery comes in. Leaked documents from Edward Snowden, a former NSA contractor, suggest 33 Thomas Street may be a secret surveillance site codenamed TITANPOINTE. These documents hint that the building houses equipment used by the National Security Agency (NSA) for mass

surveillance programs.

Uncertainties: The NSA has never confirmed nor denied using 33 Thomas Street. While the building’s design and location are consistent with a potential NSA facility, concrete proof is lacking.

So, the truth? 33 Thomas Street is a telecommunications building with a secure design. It’s highly likely it’s used for some level of government communications, but the extent of NSA involvement remains unconfirmed.