President Donald Trump revealed March 29 that the U.S. military is constructing a sweeping underground complex beneath the new $400 million White House ballroom, describing the project as a security measure that only became public through a lawsuit challenging the building’s approval.
"The military is building a massive complex under the ballroom, and that's under construction, and we're doing very well," Trump told reporters aboard Air Force One Sunday. "So we're ahead of schedule."
Trump: This is a view of the columns as they are going to be made. They're going to be hand-carved and they're beautiful. Top of the line. They'll be corinthian, which is considered the best, most beautiful by far. pic.twitter.com/VGEdSlSYqr
— Acyn (@Acyn) March 30, 2026
"The ballroom essentially becomes a shed for what's being built under," he added.
Trump said the details only became public through litigation brought by a historic preservation group attempting to halt construction of the 90,000-square-foot ballroom project.
"This has come out recently because of a stupid lawsuit that was filed," he said.
The White House confirmed the underground project is a matter of national security, declining to offer further specifics.
Details about the underground construction surfaced after a December 2025 lawsuit filed by the National Trust for Historic Preservation, which is seeking to halt the ballroom project pending environmental review and congressional approval. A federal judge is expected to rule on the case by the end of March.
The administration has defended the ballroom’s construction as a long-sought addition to the White House for hosting large events, while critics have raised concerns about its cost, transparency, and impact on the historic site.
Despite claims that the ballroom is a waste of taxpayer dollars, it is not a publicly funded effort. As the White House announced when the project began, Trump himself and “patriot donors” are backing the ambitious project privately.
According to Open Secrets, “Major technology and AI firms” are among the contributors behind the building project, including “cloud giants such as Amazon, Microsoft and Google; data and analytics contractors like Palantir and Booz Allen; and consumer tech companies such as Apple and Meta.”
In addition, defense contractors Lockheed Martin, a number of cryptocurrency companies, AI chipmaker Nvidia, and Alphabet (parent company of Google) contributed to the ballroom’s construction as well.
Trump has said the ballroom will be ready by 2028. He expressed confidence in the finished product March 29, saying, "I think it'll be the greatest ballroom anywhere in the world.”