Get acquainted with our Earth’s deepest man-made structures

By Sarah Arksey
Associate Writer

Though it’s more widely known for its recognizable outer architecture, the Sydney Opera House’s underground parking garage is 37 meters deep and considered the deepest basement in the world. However, the impressive depth of this car park will be long overshadowed by the time we reach the end of this list!

Metro Stations

The three deepest metro lines in the world all took their design inspiration from the model seen in many Communist countries, which allows the structures to function as bomb shelters if necessary.

Parts of the Pyongyang Metro in North Korea clock in at 360 feet deep, making this the deepest metro line in the world. The well-shrouded underground structure is also one of the only places foreign visitors can mingle with locals.

Arsenalna Station on the Kyiv Metro in Ukraine is 346 feet deep and the world’s second-deepest metro station. The station is currently being used to shelter civilians when they are alerted of a potential Russian airstrike. The world’s third deepest metro station, Admiralteyskaya, is located across the border in St. Petersburg, Russia, 282 feet below the ground.

Bunkers

The depth, expansion, and even existence of the world’s nuclear bunkers is somewhat shrouded in mystery. After all, should we need to use them, global tension is likely at an all-time high!

One of the deepest bunkers in the world (that we know of) is the Cheyenne Mountain Complex, a United States military bunker that sits 2,000 feet under Cheyenne Mountain, just outside of the town of Colorado Springs.

The building houses NORAD, U.S. Northern Command, Air Force Space Command, and U.S. 

Strategic Command operatives. The bunker is considered “one of the most secure buildings in the world”. Constructed from battleship steel, the complex can (allegedly) survive a 30-megaton nuclear explosion.

In terms of private bunkers, the Europa One shelters by Vivos run an impressive 394 ft deep. The bunkers’ infrastructure was originally

constructed by Soviet forces during the Cold War but has been transformed into a luxurious space akin to an ‘underground cruise ship’, outfitted with pools, theatres, and bars. The complex also plans to house a zoological collection and a ‘DNA Vault’ containing genetic material from millions of donors.

These luxury bunkers located in Rothenstein, Germany are reserved for the super-elite and are invitation only. The bunkers are touted as the safest and most comfortable nuclear shelters in the world and are said to run roughly $5 million per person. Vivos does offer surprisingly affordable options, however. Their xPoint shelters in South Dakota house up to 24 people and start at just $35,000.

Located in the world’s second-most populous country, China’s Nuclear Command Bunker (6,561 feet) is designed to house a whopping 1 million people in the event of a nuclear attack, making it by far the largest ‘underground city’ in the world. It is also the deepest bunker that we know of.

The use or threat of nuclear warfare has resulted in the construction of many of the world’s deepest buildings. The Onkalo Spent Nuclear

 Fuel Repository in Finland reaches a depth of 1743 feet– the deepest building of its kind. The facility is so large that it is estimated to be capable of accepting nuclear waste for storage for the next 100,000 years, beginning in 2025. After the storing process– which will be handled by robotic vehicles– has begun, no human being should enter the area.

Research Centers

The European Organization for Nuclear Research- or CERN, as it is more commonly known- straddles the France-Swiss border near Geneva, Switzerland, and is renowned worldwide for its advancements in physics. The Large Hadron Collider sits underneath the main building and takes the form of a 27-kilometer (nearly 16-mile) ring of superconducting electromagnets, which essentially boost the speed of particles until they collide together, traveling close to the speed of light.

One goal of the Collider is to mimic the Big Bang in a controlled environment in hopes of unlocking the secrets of our universe’s origin. At its deepest point, the CERN structures reach 574 feet in depth.

The Sudbury Neutrino Observatory in Canada reaches 6,890 feet deep. As the name suggests, the center was established to study solar neutrinos– tiny subatomic particles that originate from our Sun’s core– by assessing their interaction with a subterranean body of water.

Finally, the deepest (and largest) known research facility, China Jinping Underground Laboratory, reaches over 7,800 feet deep. The lab was created to facilitate the study of dark matter– the mysterious substance said to make up over 80% of our universe.

Mines 

We’ve now surpassed the depth where most human activities can be conducted- some of the deepest structures in the world are mines. Poland’s incredible Wieliczka Salt Mine reaches a depth of (1,073 ft)- greater than the Eiffel Tower’s height, and expands via tunnels for over 178 miles.

During the near-millennia that the mine was operational, several features were added, including four chapels carved out of salt. The mine also features several underground lakes. The mine was established in the 13th century and produced table salt consistently until 1996.

The mine draws nearly 2 million visitors per year, who can access several chambers and tunnels, the lakes, St Kinga’s Chapel, a restaurant, and even a space for concerts and events– all of which constitute just 2% of the mine open to the public.

Wieliczka Salt Mine

Despite Wieliczka Salt Mine’s expansive nature, it doesn’t hold a candle to the following five structures in terms of depth. These mines are thought to be the deepest man-made buildings in the world: Morro Velho (9,800 feet), Kolar Gold Fields (10,500 feet), Empire Mine State Historic Park (11,007 feet), TauTona Mine (12,800 feet), and our winner– the Mponeng Gold Mine (13,100 feet) in South Africa.

The Mponeng Gold Mine reaches close enough to the Earth’s core that the rock at its lowest point can reach over 150 degrees Fahrenheit– more than hot enough to fry an egg! The mine relies on an intricate cooling system to keep workers safe, and unfortunately, deaths are not uncommon. Mining is one of the most dangerous professions in the world, accounting for about 12,000 annual deaths worldwide.

Bonus: Kola Superdeep Borehole

This borehole, drilled in Russia near the Norwegian border to study the Earth’s crust, reaches a whopping 40,230 feet towards the Earth’s core. Though not technically a building, we’ve included this structure for its sheer depth– so great that further drilling is currently impossible, as the heat at such a depth can melt stone.

The hole, which is eight times deeper than the Marianas Trench, has sparked urban legends that claim that the hole was drilled so deep that it broke into Hell.