When you think about a city, you picture its bustling streets, towering skyscrapers and sprawling parks. Yet, a staggering portion of urban space remains off‑limits, tucked beneath the surface where ordinary eyes rarely wander. In fact, the majority of a city’s footprint can be hidden underground, and the phenomenon is especially striking when you consider the ten underground cities that are officially off‑limits to the public.
Why 10 Underground Cities Remain Out of Sight
From imperial bunkers and Cold‑War shelters to secret railway lines and forgotten quarries, each of these subterranean realms tells a story of power, paranoia and ingenuity. Below, we count down the ten most fascinating underground cities you’re not allowed to see, complete with the eerie details that keep them shrouded in mystery.
10 . Mumbai’s Imperial Underworld
Whenever a conquering power takes control of a territory, it often leaves a hidden legacy beneath the cityscape. In Mumbai, British‑era construction crews frequently stumble upon mysterious chambers whose original purposes have been lost to time. Take, for example, the vaulted space discovered beneath Kolkata’s National Library – a structure that could have served as a treasury, a torture chamber, or simply as part of the building’s foundations.
Mumbai itself boasts a veritable maze of abandoned imperial constructions. Among them is a thirteen‑room bunker hidden beneath Raj Bhavan, the city’s governing mansion, and a kilometer‑long tunnel that snakes under the old General Post Office. These subterranean relics hint at a hidden world of military and administrative planning.
The most recent revelation came in 2022, when a two‑hundred‑meter tunnel was uncovered beneath JJ Hospital – a facility whose foundations were laid by a British governor. The tunnel, absent from any official maps, was discovered during a routine water‑leak investigation and appears to be blocked at one end, leaving its original destination a tantalising mystery. Whether it once linked to a neighboring hospital or served some other clandestine purpose, the find underscores how many more secret passages may still be waiting beneath Mumbai’s streets.
9 . LA’s Prohibition Partyways
While the rest of the United States grappled with the first wave of prohibition, Los Angeles kept the booze flowing through an elaborate network of underground service tunnels. These passageways allowed the city’s flappers and dapper gentlemen to slip from one hidden bar to another without ever seeing the law‑enforcing eye.
Originally built for utility purposes and even as a subway to ease surface traffic, the tunnels stretch for more than seventeen kilometres, linking basements that were transformed into speakeasies. Notable venues include the King Eddy Saloon, which migrated underground after twenty years of operation, converting its storefront into a piano shop to survive. Other legendary spots are the Edison, tucked beneath the city’s first privately owned power plant, and Cole’s, hidden under the Pacific Electric building. Patrons accessed these secret haunts using passwords, moving through the darkness while remaining invisible to police and paparazzi.
Today, most of these passages are sealed off and largely unmapped. Many have succumbed to flooding and decay, yet graffiti and whispered rumors reveal that some still function. Atlas Obscura even notes an “easy‑to‑miss elevator” on Temple Street, and there’s talk of a clandestine entrance that links Downtown to Hollywood via the subway. Though officially closed, the underground partyways continue to captivate the imagination of those who love a good secret.
8 . Havana’s Secret Chambers
In the early 1990s, Cuba reportedly embarked on an ambitious project to dig more than thirty‑three kilometres of tunnels beneath its capital. Intended as bomb shelters amid escalating tensions with the United States, these subterranean corridors were manually excavated by hundreds of laborers, their entrances carefully concealed from public view.
Known collectively as the Popular Tunnels, they represent the latest chapter in a long Cuban tradition of underground construction. Back in 1929, the New York Times reported the discovery of five secret chambers hidden beneath Havana’s City Hall, hinting at a legacy of covert engineering that predates the Cold War era.
7 . Tokyo’s Hidden Network
Tokyo’s reputation for futuristic skylines masks an intricate web of hidden waterways, forgotten canals and the world’s largest sewer system. Yet, beyond the documented infrastructure, journalist Shun Akiba uncovered evidence suggesting a far more extensive and deliberately concealed network.
By comparing historic and contemporary maps, Akiba noticed discrepancies that hinted at unknown tunnels and attempts to erase them from official records. For instance, newer schematics show subway lines intersecting near the National Diet building, while older maps depict them as parallel, implying a concealed complex between the Diet and the Prime Minister’s residence. He also observed mysterious tunnel extensions off the Ginza Line. Official inquiries yielded little, with officials maintaining “zipped‑tight” lips despite Akiba’s credentials as a war correspondent for Asahi TV. He estimates up to two thousand kilometres of tunnels beneath the metropolis—eight times the officially reported 250 km. Some lines, such as the Namboku, Hanzomon and O‑Edo, were built long before their conversion to passenger service, and the deepest station, Kokkai‑gijidōmae on the Chiyoda Line, may have originally functioned as a bomb shelter. Additionally, the Yurakucho Line, with its unusually high ceilings and military‑grade facilities, is rumored to serve as a secret road for the armed forces. Though the network dates back to World War II and the Cold War, the persistent silence suggests many sections remain active.
6 . Washington’s Whack‑a‑Mole Hidey‑Holes
The United States capital harbours a sprawling labyrinth of tunnels designed to keep its political elite out of the public eye. Both major parties of the nation’s military‑industrial complex have embraced these subterranean routes, using them to move personnel and equipment discreetly. During the 2021 Capitol siege, several of these passages served as emergency evacuation routes, but they are routinely employed to avoid the elements.
According to The Drive, at least nineteen underground passages criss‑cross Capitol Hill, some dating back to the 1800s when they were constructed for water, ventilation, and even an electric conveyor system that shuttled books between the Capitol and the Library of Congress. The early‑1900s saw the Russell building equipped with a fortified subway car tunnel later designated as a fallout shelter. Over the decades, the network expanded, and today the Cannon Tunnel—linking the Cannon building with the Capitol—resembles an underground town, complete with a shoe‑repair shop, post office, credit union and cafeteria.
In the 2000s, a massive 54,000‑square‑metre expansion added three new underground stories to the Capitol’s complex, linking nearby offices and installing a 305‑metre tunnel for screening garbage trucks for explosives. This development coincided with growing secrecy around Washington’s underworld, not to mention the hidden tunnels and bunkers that lie deep beneath the White House itself.
5 . Moscow’s Many Secrets
The Kremlin, Europe’s most renowned fortress, rests atop a maze of secret passageways. Notable among them is the haunted Neglinnaya River tunnel, the Syani stone mines that supplied limestone for centuries, and the legendary, still‑unfound library of Ivan the Terrible. Excavations aimed at locating the library have only yielded endless, stone‑lined tunnels, prompting officials to abandon the search due to concerns over structural damage.
Discovered dungeons beneath two Kremlin towers once held prisoners such as Prince Andrei Khovansky, who was confined by Ivan the Terrible. Those condemned to torture were gagged, chained to walls and allowed to speak only when addressed. Nearby, the Cathedral of the Archangel housed its own dungeons, where debtors and church offenders endured punishment on “penitence chairs.” Adjacent stone treasuries were built to resist fire and theft. In more recent times, the secret Metro‑2—an underground parallel subway system—was constructed to evacuate government officials, reaching depths of up to 250 metres. Its existence was confirmed by Moscow’s first post‑Soviet mayor in 2006, yet details remain scarce.
4 . New York’s Abandoned Subways
New York City hides a plethora of disused rail tunnels beneath its bustling streets. Among the most storied is Track 61, located under the Waldorf Astoria, which once ferried presidents and generals such as Roosevelt and MacArthur. In 2003, it was even considered as an emergency escape route for President George Bush. The tunnel has also hosted fashion shows and an Andy Warhol event.
Another forgotten conduit is the Atlantic Avenue Tunnel in Brooklyn, abandoned since 1861 after just twenty years of service. Built in 1844, it holds the distinction of being the world’s oldest subway tunnel and was briefly reopened in 1918 to search for German saboteurs. Beyond rail, New York houses a unique 66‑kilometre underground aqueduct—the 1842 Croton Aqueduct—linking Bryant Park to the Croton River in Westchester. Decommissioned in the 1950s, the aqueduct remains “perfectly preserved,” with its massive distributing reservoir in Bryant Park resembling an ancient Egyptian temple, a testament to the engineering that solved the city’s historic sanitation crises.
3 . Rome’s Ancient Quarries
Rome’s subterranean landscape is a sprawling labyrinth of ancient quarries and tunnels that date back to the city’s founding. Their sheer extent has led to frequent sinkholes and surface building collapses. In 2013, geologists finally mapped the network after a spate of incidents—44 collapses in 2011, 77 in 2012, and 83 by the end of 2013—often patched up by residents with makeshift cement bags.
The original Roman tunnelers deliberately kept passages narrow to maintain surface stability. Over centuries, however, weathering and later generations’ widening of these tunnels have compromised that stability. Despite these challenges, the underground spaces have served myriad purposes: catacombs, sewers, mushroom farms, and even wartime shelters during World War II.
2 . London’s Tunnels of Intrigue
London’s underworld is a tapestry of dungeons, crypts, catacombs, thirteen underground rivers and plague pits dating back to the mid‑1300s. In recent years, officials confirmed what urban explorers have long suspected: a sprawling network of tunnels linking government buildings with secret chambers. According to the 2017 Land Registry, the majority of these passages were constructed by the Post Office, British Telecom and the Ministry of Defence.
One particularly intriguing segment is the Postmaster General’s tunnel, stretching from the East End to the former War Office at 57 Whitehall (now a luxury hotel). Elevator shafts along this route connect to various government departments and telephone exchanges. Deep beneath High Holborn, close to Whitehall, a bomb‑shelter‑turned‑underground complex once housed a restaurant, games rooms and two bars—one serving tea, the other alcohol.
Although officially deemed obsolete since the Cold War, the tunnels remain sealed from the public. Those fortunate enough to gain entry describe a time‑capsule atmosphere, with lights perpetually on and deeper levels bricked off. Trespassers who venture too far often face disproportionate penalties, keeping the subterranean world largely a secret.
1 . Beijing’s Underground City
During the Cold War, Beijing constructed an astonishing underground metropolis—known as the dixia cheng or “underground city”—spanning an impressive 85 square kilometres. Hand‑dug by citizens, the complex was designed to shelter up to forty percent of the population in the event of a war with Russia, earning it the nickname “underground Great Wall of China.”
The official guided tour only showcases a tiny, commercialised loop of the vast network. Rumours suggest that the remaining corridors, tunnels and bunkers house up to one million homeless individuals, dubbed the “Rat Tribe.” While some sections have been converted into low‑cost apartments, it is hard to imagine the Chinese government allowing such extensive space to fall into the hands of the destitute when it could serve numerous strategic purposes. With ninety entrances scattered across the city, the complex could also facilitate the disappearance of individuals, a chilling possibility.
Regardless of the speculation, the underground city was built for long‑term habitation. It includes storage facilities for grain, mushroom farms, restaurants, barber shops, a cinema, classrooms and other amenities designed to maintain a semblance of normal life even deep beneath the surface.