Billionaire ‘doomsday’ bunkers: Why are the ultra-rich buying these underground mansions?

This development has further intensified public curiosity surrounding these high-profile underground shelters.

Zuckerberg’s underground bunker will be located on the $100 million island, featuring self-sustainable resources, leading many to speculate that he is preparing for a doomsday scenario.

The project, known as Koolau Ranch, is shrouded in secrecy and has strict non-disclosure agreements in place for all workers involved.

The compound comprises a series of buildings, including two main mansions connected by a tunnel leading to a 5,000 square-foot underground shelter with an escape hatch.

The proposed Zuckerberg mansion boasts numerous bedrooms and bathrooms, guest houses, and a collection of tree houses connected by rope bridges.

The property is designed to be self-sufficient and features blast-resistant doors, keypad locks, soundproofing, surveillance cameras, and a secret door in the library.

With an estimated land purchase cost of $170 million, this project reflects Zuckerberg’s significant investment in creating a fortified family home.

While details surrounding the true intention behind the compound remain speculative, the inclusion of an underground bunker and preparations for self-sufficiency suggest a focus on preparedness for potential disasters or security concerns.

Billionaire bunkers: What are they?

Billionaire bunkers or doomsday bunkers are underground accommodations built to sustain unprecedented crises such a war, calamities, an outbreak of a contagious disease or even a zombie apocalypse.

Often a choice for ultra-wealthy buyers, doomsday bunkers are a safe living space for families, and are well-equipped with essentials and other necessities.

These bunkers are also of interest to some ultra-high net worth individuals in the UAE, Swiss firm Oppidum told Arabian Business in a past interview.

“We take an optimistic view of the world and our clients select an Oppidum in very safe and secure places like the UAE for various reasons,” the firm said in an emailed comment.

“We don’t discuss individual clients, but in general terms we have had interest from people and families who wish to protect significant collections of rare and valuable art or automobiles, likewise some clients require a highly secure space to conduct sensitive business meetings. It may also be a luxurious extension of an existing property that does not intrude on their grounds at surface level.

“Many see an Oppidum as a beautifully appointed and luxurious addition to their existing home and a place where they can enjoy their collections and time with their families in the knowledge that these possessions and the people they love are afforded the very highest level of protection should circumstances dictate,” the company said.

The demand for doomsday bunkers designed to withstand catastrophic events such as war first surged during the escalating tensions between Russia and Ukraine.

Luxury living in times of trouble

One such project, called L’Héritage, is being developed by French architect Marc Prigent under the brand Oppidum.

These luxurious bunkers offer buyers a customisable and secure underground space while providing an above-ground residential estate for a comfortable living experience.

Situated in a secluded location, L’Héritage ensures residents can quickly access the bunker through a secret corridor and seal it with a blast door in less than a minute in the event of a dangerous situation.

Once the threat subsides, inhabitants can safely return to their above-ground residences. The compound features multiple high-security systems, including fortified walls, detection sensors, and automated defense technology.

Maintaining strong communication with the outside world is a priority, and the estate incorporates advanced biometric systems for resident identification.

The Oppidum project constantly upgrades its technology to harness the latest advancements in areas such as energy storage, power generation, building management systems, and security elements.

Vertical farming technology is also implemented to ensure a sustainable food supply for residents.

The bunkers boast an internal sub-system that controls emergency modes, CBRN (chemical, biological, radiological, and nuclear) filtration, oxygen levels, and more, allowing for seamless transition to offline operation in case of emergencies.

The residences are equipped with two independent air filtration systems that provide indefinite fresh air and protect against airborne contaminants, including those of radioactive or chemical origin.

Constructed with reinforced concrete shells capable of withstanding various loads, blast waves, seismic activity, and radiation, the bunkers can be designed to meet the highest level of protection specified by NATO standards.

While project prices start at $60 million, there is no upper limit on the final design cost, reflecting the level of customisation and luxury offered to potential buyers.

Other projects include Linear and Futurist, with prices starting at $8 million and $15 million, respectively.