Secret passages are hidden in the most unexpected places. Of course, you may find some in history filled castles and palaces, but they exist in other places, too. Check out some of the amazing hidden tunnels we have found lurking everywhere from beneath the seat of government, to below bustling city streets, and even deep inside the country hillside.
The Fishbones, Lyon, France
Over two dozen 100-foot-long finished tunnels run below the La Croix-Rousse neighborhood in Lyon, France. The tunnels were discovered in 1959, but date to before the Middle Ages. They were named for the shape of their structure, which, when mapped out, resembles a fish skeleton.
The tunnels aren’t open to the public and can only be accessed by manholes. Many people believe there is a secret entrance to them at the Saint Bernard Church. Conspiracy theories abound as the tunnels are built on land once owned by the last Grand Master of the Knights Templar.
Tunnels of Củ Chi, Củ Chi, Vietnam
Tunnels beneath the jungles of Củ Chi District connected Viet Cong troops to Ho Chi Minh City. The secret tunnels were used to move supplies and soldiers, as well as for hiding places and even housing. The tunnels protected the fighters from enemy fire.
Life in the tunnels was hard, and they were not comfortable places to live. Soldiers were forced below ground for days at a time. Supplies and food had to be rationed and the tunnels were far from safe or clean. Today visitors can see what life was like for the fighters as the tunnels are now open to the public.
Initiation Well at Quinta da Regaleira, Sintra, Portugal
Quinta da Regaleira is a gorgeous palace in Sinatra, Portugal. It was built in 1910 by António Augusto de Carvalho Monteiro, an outspoken and eccentric Freemason. Inside the palace are matching 88 feet deep wells. Each well has a spiral staircase lining its walls and a tiled floor at the bottom. Secret society rituals were rumored to have been done at the bottom of these wells.
An even stranger mystery are the caves that lie beyond the wells. The caves may look natural at first glance, but they are hand hewn. Although these secret caves are relatively young, it’s no wonder why they have created such a buzz with their placement beneath a gothic palace and a connection to Freemasonry.
Passetto di Borgo, Rome, Italy
Although it isn’t much of a secret now, the Passetto di Borgo in Rome was originally built as a passage for the Pope to escape danger. The passage is hidden in what looks from the outside to be an average city wall of the time.
The Passetto di Borgo was built in 1277 and added onto in 1492. As far as anyone knows, the passage has only been used by the Pope twice, and that was back around 1500. The tunnel was renovated in 2000 and can now be visited by the public, making it a popular tourist attraction.
Capitol Hill Tunnels, Washington, D.C., USA
Capitol Hill is the home of the United States government. It is a web of streets connecting a number of different buildings and complexes together. Under the streets are tunnels that are busy making their own connections.
Tunnels run beneath the government buildings to provide a better, faster, and safer way for the elite of Washington to move from one government building to the next. There is also a subway train that runs three routes: one to the House of Representatives, and two to the Russell Senate Office Building.
WWII Tunnels in The Rock of Gibraltar, Gibraltar
Gibraltar was a strategic stronghold for the British during World War II. The Rock of Gibralter is by far and away its most famous landmark. However, many people do not know you can go inside the landmark and discover a whole world of history.
Winston Churchill commissioned the tunnels in the Rock of Gibraltar. They were used as a strategic location for housing supplies, a hospital, and troops. The tunnels are so massive they can house an entire garrison with enough supplies to last six months.
Escape Tunnel at Bran Castle, Transylvania, Romania
Bran Castle is steeped in lore and legend. Many believe it is the inspiration for Bram Stoker’s Dracula and the one time home of Vlad the Impaler. Considering the fantastical stories surrounding it, you probably won’t be surprised to know that there are secret tunnels within the castle.
A faux fireplace hides a secret staircase allowing an undetected escape from the castle. It was found when Queen Marie of Romania decided to renovate the castle. Visitors can see the passageway now as part of the castle tour, where it is a main attraction.
Kingsway Exchange Tunnels, London, UK
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More than 130 feet below Chancery Lane in London are fortified tunnels that were once used as a secret bomb shelter. They were eventually used as a headquarters for a covert offshoot of MI6 working to thwart German efforts during WWII.
The tunnels had another incarnation as the Kingsway Telephone Exchange which housed a secret direct line between the White House and the Soviet Premier. In the 1980s, it was sold off to a telecom company.
Lynnewood Hall’s Tunnels, Pennsylvania, USA
Lynnewood Hall is a Gilded Age estate and one of America’s largest historic homes. Its 480 acres are full of mystery and tragedy, and it has been left abandoned for more than a decade, mostly seen only by the occasional explorer.
Abandoned Southeast explored the property in 2023 and discovered a huge tunnel system beneath the home believed to have been part of the plumbing and drainage system. The Lynnewood Hall Preservation Foundation has now purchased the magnificent home and intends to restore it to its original splendor.
Secret Passage in the House of Commons, London, UK
There is a secret passage in the House of Commons in London and it wasn’t discovered until 2020! The passage dates back to the coronation of King Charles II in 1660. It was made to give guests a quick, easy route to Westminster Hall during the ceremony.
This passage was sealed in 1851, but otherwise left intact and largely forgotten about. It is noted that the passage was discovered again in the 1950s when the building was being repaired from bomb damage caused during the Second World War, only for it to be quickly forgotten again, until now.
Túnel de Bonaparte, Madrid, Spain
The Túnel de Bonaparte in Madrid, Spain has quite an illustrious past. It is a simple tunnel done in neo-classical style that runs from the Campo del Moro palace gardens and Casa de Campo. It served as an escape route for Joseph I and Ferdinand VII out of the capital city.
The Túnel de Bonaparte is just a small fraction of the 2,485 miles of tunnels beneath Madrid. For many years it was turned into a public park. However, with modern road construction, it has been closed to the public and mostly lost to history.
Erdstall Tunnels, Europe
There are more than 2,000 known Erdstall tunnels that exist throughout Europe. They are most common in southeastern Germany. The tunnels are thousands of years old, although no one knows exactly when they were built or who built them.
The Erdstall tunnels range from 60 to 160 feet long and are only an average of 1.3 feet in diameter. Since it would be hard for a person to go through such tight spaces, historians are puzzled by what the tunnels may have been used for.
Festungsfront Oder-Warthe-Bogen, Międzyrzecz, Poland
Międzyrzecz, Poland is home to a rather unassuming entrance into an extraordinarily elaborate system of tunnels. The tunnels were built as part of Nazi Germany’s war machine and were designed as a key military defense line. The web of tunnels is believed to be about 25 miles long and more than 130 feet below ground.
The tunnels below Międzyrzecz, Poland provide a vast enough area to house military troops. They included barracks, generators, and workshops. Abandoned since the end of the war, the tunnels are now a nature reserve for bats.
Secret Entrance to the Knickerbocker Hotel, New York, USA
There is a secret entrance to the Knickerbocker Hotel bar, in New York City. The hotel was a huge attraction in the early 1900s. It was once owned by Jacob Astor IV and is the birthplace of the martini.
While NYC has plenty of underground tunnels and they all have a story, this secret entrance is unique. It is marked only by a small plaque with the name of the hotel and was probably used by VIPs to come and go undetected. While the plaque remains, the entrance has been long since closed off.
Marie Antoinette’s Secret Suite, Versailles, France
Marie Antoinette’s private apartments in the Palace of Versailles take luxury and opulence to the next level. It was here that she both entertained as well as had some of her most private family moments. However, there is more to the infamous queen’s apartment.
In a wall panel near the bed, there is a secret entrance to an entirely hidden suite of rooms. These rooms provided a refuge from the court and allowed the queen to find moments of true privacy. The hidden rooms included a library and a lounge. The rooms have been recently renovated and are open to the public.
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