Nobody working on this project is allowed to talk about what they’re building. Almost anyone who passes compound security—from carpenters to electricians to painters to security guards—is bound by a strict nondisclosure agreement
……
the planning and construction of the roughly 1,400-acre compound has been shrouded in secrecy. The property, known as Koolau Ranch, will, according to planning documents, include a 5,000-square-foot underground shelter, have its own energy and food supplies, and, when coupled with land purchase prices, will cost in excess of $270 million.
https://www.wired.com/story/mark-zuckerberg-inside-hawaii-compound/