The president of the United States ordered the secret construction of a secure underground facility at the White House and built a new extension of the East Wing on top.

It was 1941, and Franklin D. Roosevelt had been encouraged to build a bomb shelter at the White House in the aftermath of the attack on Pearl Harbor.

At the time, “no public acknowledgment was made of there being a bomb shelter under construction, only the East Wing,” according to White House Historical Association historian Bill Seale.

More than 80 years later, the East Wing is again under construction in preparation for President Donald Trump’s sprawling new ballroom, and the historic, if dated, underground facilities have been dismantled. And once again, there’s a lot of secrecy around plans to rebuild the bunker.

Little is publicly known about the construction taking place in what was once a secret submarine-like bunker, which included the Presidential Emergency Operations Centre, and the underground infrastructure around it. The space has been used for everything from watching a parody film the Nixon administration deemed pornographic and wanted killed, to planning former President Joe Biden’s clandestine trip to Ukraine. Then-Vice President Dick Cheney was evacuated to the space moments before an attack on the Pentagon on September 11, 2001.

The space is now likely being reimagined and replaced with new technology to counter evolving threats, according to a source with knowledge of the matter.

But there has been very little acknowledgment that the project even exists.

During a recent meeting of the National Capital Planning Commission where the ballroom was discussed, White House director of management and administration Joshua Fisher said broadly that the overall ballroom project will “(enhance) mission critical functionality,” “make necessary security enhancements” and “(deliver) resilient, adaptive infrastructure aligned with future mission needs.”

Fisher was pressed on why the project broke with precedent by starting the demolition process without the commission’s approval — and he indicated that the “top-secret” work taking place underground was the motivation.

“There are some things regarding this project that are, frankly, of top-secret nature that we are currently working on. That does not preclude us from changing the above-grade structure, but that work needed to be considered when doing this project, which was not part of the NCPC process,” he said.

The White House declined CNN’s request for comment. But in a court filing last week for a case seeking to stop the East Wing construction, the White House defended the process, saying that halting the underground construction would “endanger national security and therefore impair the public interest.” It said the reasoning for this was described in a “classified declaration” attached to the case.

Here’s what we know about what was there before — and what’s going on now.

Though Roosevelt’s construction was initially envisioned as a bomb shelter, underground facilities beneath the East Wing evolved over time to serve multiple functions.

Those who enter through the East Wing would go down a few levels and then walk through a massive, protected vault-style door to enter a self-contained bunker with low ceilings that included beds, shelf-stable foods, water, and other supplies, plus secure communications to the outside world, according to a source who has been inside the space and was not authorized to speak on the record.

The PEOC works in tandem with the Situation Room, said Jonathan Wackrow, a former US Secret Service agent and CNN contributor.

“The Situation Room is a much more focused watch centre that will feed information over to the PEOC, but because it is a complex that’s in the West Wing, it is secure to a point, but it’s not a hardened facility,” he said.

“The PEOC is used during emergencies. It’s not something that everybody goes to,” he added. “The Situation Room is used almost by the whole of government, 24 hours-a day.”

The PEOC has been depicted on the silver screen with varying degrees of accuracy — most recently in the 2025 thriller “A House of Dynamite,” along with 2013’s “Olympus Has Fallen,” which depicted a terror attack on the White House.

The “tomb-like” space was visited by Roosevelt only once, according to Seale, the historian. In subsequent years, “an inspection of the bomb shelter became a first-day custom for all incoming presidents who followed, until the last twenty years, when the relevance of the shelter was lessened,” he wrote in 2011.

A second source familiar with the space granted anonymity to speak freely described the underground complex as “a very complicated submarine that was built in the 1940s — a self-contained unit, [with] separate power backups, separate water backups, separate air filtration.”

“But all the infrastructure is 1940s infrastructure,” they added.

The complex also had a secure evacuation route, according to the first source, through which the president can be removed from White House grounds to another location.

Demolition on the East Wing began in October, and the excavators that dismantled the East Colonnade and office space historically occupied by first ladies took the dated underground facility along with it.

“With a high degree of confidence, I would say that all of the subterranean structures,” including the PEOC, heating and air utilities, and underground facilities for the White House Military Office and US Secret Service Uniformed Division, “all of that seems to be gone,” the second source said.

For anyone concerned about presidential security in the absence of the bunker, that source said there are plenty of redundancies to keep the president safe in the event of an emergency.

Trump has suggested the US military is “very much involved” in the ballroom construction, and it’s likely that the project is being executed by some combination of military officials; Secret Service; the Executive Office of the President; contractor Clark Construction, which has significant experience in highly secure facility construction; and Shalom Baranes Architects, the group leading the ballroom construction, which also led the project to rebuild and fortify the Pentagon after the 9/11 attack.

Wackrow, now a risk management executive, predicted that whatever replaces the underground space will be able to anticipate and respond to emerging threats, including kinetic threats like a nuclear explosion or plane crash; chemical or biological instruments; or electromagnetic pulses, among other potential concerns, and do so without telegraphing details to potential adversaries.

“You have to think about a facility that can be built in secret, highly classified, that can sustain the current and future state threat environment,” he said.

What will be virtually impossible: learning how much this aspect of construction costs. Trump has offered an ever-growing price tag on the ballroom aspect of the project, which started at $200 million and is now up to $400 million, but that doesn’t account for what will happen underground. Trump has made clear that the ballroom will be paid for by private donors, but any subterranean security infrastructure will ultimately be paid for by American taxpayers.

“If you think about trying to mitigate the threats today and the threats for tomorrow, you’re really talking about emerging technologies, emerging infrastructure — stuff that may not be commercially available. We’re never going to get the line of sight on how much that costs,” Wackrow said. (CNN)