The world is full of wonders—and there are just as many below the ground as there are above it. Indeed, if “spooky” is your name, the seemingly unending variety of underground tunnel systems you can actually visit throughout the world will definitely be your game.
Many underground tunnel systems have developed a reputation over the years. The Paris Catacombs, for example, have been on many a Francophone’s travel bucket list since they opened to the public in 1874. (Yes, they opened that long ago; before that, only those of high status could make an appointment. Since 2013, though, they’ve been under the management of the Paris Musées, the public entity that manages Paris’s 14 municipal museums.)
However, other underground tunnel systems remain lesser-known—even though they, too, have been open to the public for safe visits for quite some time. These 11 tunnel systems will satisfy your exploratory spirit—and maybe even give you a few satisfying chills while you’re at it.
The Seattle Underground: Seattle, Washington
When white colonists arrived in Seattle in 1851, they made a huge mistake right off the bat: They built their settlement right on the beach. This poor building choice resulted in decades of flooding and sewage management problems—and, ultimately, a fire in 1889 that burned down 30 blocks of the downtown area. When the time came to rebuild, the city implemented two changes: First, buildings had to be constructed out of stone or brick rather than wood; and second, the streets would be regraded, bumped up two stories from where they had previously been situated.
Interestingly, though, the regrading didn’t eliminate the retail, dining, and living space on the original street level; it just added to it. As new buildings and sidewalks went up on the higher levels, the lower ones continued to function as well—and voila: an underground tunnel system complete with shops, restaurants, banks, and more, all operating just below the surface of what’s now called Pioneer Square, was born.
Eventually, of course, the tunnels did fall into disuse—but in the 1950s, Seattle local Bill Speidel took it upon himself to head up restoration efforts for both the Underground and Pioneer Square itself. He began running tours into the Underground in 1965, and although he passed away in 1987, his legacy lives on: You can still take the tour he started today. A regular tour of the Seattle Underground is $22 for adults; or, if you’re feeling spooky, you can take the Underground Paranormal Experience tour for $33.
Cuevas de la Villa: Valencia, Spain
During the era in which Spain was under Moorish rule, many houses and dwellings in the Plaza de la Villa area of Valencia were constructed with caves directly beneath them. The geological nature of the land lent itself well to the purpose; the area was (and still is) located atop a large platform of limestone tuff—a soft variety of volcanic rock that’s easy to drill. The caves made excellent cellars and were frequently used as storerooms, wine-making facilities, and, occasionally, hideaways.
But although the caves were often in use throughout the 12th and 13th centuries, they were lost in the 17th century when all the homes in the plaza were demolished. Thankfully, in the 1970s they were rediscovered, excavated, and—intriguingly—joined together via the construction of a network of tunnels.
You can now visit the caves (and wander from cellar to cellar and from house to house using the tunnels that connect them all together). Tickets are a mere four euros for adults; also, there are a number of combination tickets offered that include the caves plus a few of Valencia’s other notable sites and attractions.
The Edinburgh Vaults: Edinburgh, Scotland
Edinburgh’s South Bridge was completed in 1788. A road bridge running from the High Street section of the Royal Mile to the spot where Chambers Street joins Infirmary Street, it has an impressive 19 arches in all; however, they’re all enclosed by buildings—and inside that enclosure is a large series of chambers known as the Edinburgh Vaults.
The Vaults have served many purposes over the centuries. Once, they offered short-term storage and workshop spaces for businesses on the South Bridge. Later—when it became apparent that the area was prone to flooding—they became both slum housing and a red-light district. It’s long been thought that body snatchers and serial killers Burke and Hare used the Vaults as a hunting ground (although these days, that’s believed to be more rumor than fact). Regardless, crime was high and sanitation was low in the area—and eventually, the Vaults were closed to the public, with piles of rubble dumped inside to prevent access. But they were rediscovered in the 1980s, and once they were dug out, it was clear that they were quite a unique piece of history.
The easiest way to get into the Vaults these days is to take a walking tour. Mercat Tours is currently the only tour company in Edinburgh with access to the space. You can choose between the Historic Underground tour, which focuses on the history of the Vaults, and the Ghostly Underground tour, which has a decidedly more terrifying bent. Additionally, Unusual Venues Edinburgh has transformed sections of the Vaults into three stunning and unique event venues: the Caves, the Rowantree, and Marlins Wynd. Who’s up for an underground wedding?
The Dupont Underground: Washington, DC
Admittedly, this one is less of a tunnel system and more like a specific tunnel—but it’s pretty neat all the same. The Dupont Underground comprises the remains of DC’s attempt to take its trolley system underground.
DC got its first electric streetcar in 1890, but although this miraculous invention solved one set of problems—it was a lot cleaner and faster than the horse-drawn carriages that made up most of the city’s street traffic at the time—it also caused another: Traffic became unbearable. So, the decision was made to move some of the traffic underground in order to free up the surface streets again. Accordingly, the underground trolley stop at Dupont Circle was the first to be built in 1949—but alas, no further construction continued afterwards. The streetcar system itself shut down less than 15 years later, closing for good in 1962.
In the decades since, the tunnels have been used as a fallout shelter, a storage unit, and (for a short period in the 1990s) an underground, trolley-themed food court; however, it was mostly left to rot. But in the 2000s, it once again started to receive some much-needed love and attention—and since 2016, the old trolley station and tunnels have been operating as an underground art space called the Dupont Underground, offering everything from gallery shows to immersive live theatre. See what’s on now at the Dupont Underground here.
Napoli Sotterranea: Naples, Italy
Like the Plaza de la Villa in Valencia, Naples is built on tuff—although this time it’s sandstone rather than limestone. Either way, though, that means that it’s easy to drill through, and as such, it’s unsurprising that there’s as much to see of Naples underground as there is above it.
The Napoli Sotterranea is located about 130 feet below the streets of the city’s Historic Center and contains remnants of every part of Naples’s rich history—from the ancient era through the Second World War and beyond. If you choose to tour it—which, happily, is easily done—you’ll see aqueducts dating back several thousand years; the remains of the Roman Theatre, beloved of the unpredictable and theatrical Emperor Nero; bomb shelters used during World War II; and more. Tours are given in both Italian and English and range between 10 and 18 euros.
The Napoli Sotterranea isn’t the only part of Naples you can visit underground, by the way; there’s also the Bourbon Tunnel, which was designed by architect Enrico Alvino as a secret royal passage for King Ferdinand II of Bourbon; the Neapolis Sotterrata, formerly a Roman market and open-air theatre; the Fontanelle Cemetery, an ossuary full of the remains of victims of historic epidemics; and the Catacombs Of San Gennaro and San Gaudioso—among others. Take your pick!
Tonkararin: Nagomi, Japan
You’ll have to go off the beaten path a bit to visit Tonkararin: The tunnels burrow through the mountains in Nagomi, a town in Japan’s Kumamoto Prefecture on the southern island of Kyushu. You’ll also want to make sure you bring your sense of adventure and a good pair of hiking boots; running for about 1,460 feet, the tunnels are so varied in size that some, according to Atlas Obscura, are “so narrow only a child could crawl through them,” while others are as high as 13 feet. And most of all, you’ll probably want to turn on your sense of wonder before you go—because no one knows who made the tunnels or why, or even when.
The tunnels do appear to be human-made; that much is clear. We also know that they were first observed in the 1970s. But their purpose has never been discovered,—Are they an aqueduct? A religious site? Just… a bunch of fissures with no actual purpose at all?—and although we found them in the 1970s, that doesn’t necessarily mean they were built at that time. No one has ever come forward to claim responsibility for them.
Most curious of all is the name “Tonkararin,” which is engraved on a sign leading to the tunnels. First, it’s written in katakana (トンカラリン), the character set typically used in Japanese to spell loanwords or other words of foreign origin—which, in turn, implies a non-Japanese origin for the tunnels; and second, the word itself is meaningless. It’s thought to be an onomatopoetic interpretation of the sound a rock makes when you drop it into one of the tunnel system’s fissures.
You can visit on your own, if you like—it’s free to see, and there’s apparently a beautiful shrine at the end of it—or you can hire a guide through a company like Explore Kumamoto.
La Crypte Archéologique de Nice: Nice, France
When new construction happens in old cities, sometimes… interesting things pop up. In Nice, for example, work on a new tramline in 2004 unearthed the remains of medieval fortifications and an epic aqueduct.
It was later determined that these structures had been razed by Louis XIV sometime around the beginning of the 18th century. The remnants remained buried for two centuries before being rediscovered—and now, after a lot of work, they’re open to the public. They’re called La Crypte Archéologique de Nice—the Archaeological Crypt of Nice.
The main space is 2,000 square meters and includes aqueducts, bridges, and walls as well as the Pairolière Tower—the tower around which the other fortifications were once organized. Access is only granted if you make a reservation for a guided tour; however, the tour guides are incredibly knowledgeable and make the journey well worth your time. The Archaeological Crypt is also accessible to people with reduced or limited mobility, a notable and welcome distinction. Tickets are just five euros for adults.
Paseo Túnel Minería Durango: Durango City, Mexico
Although it’s mostly known for agriculture and livestock today, what’s now called Durango City or Victoria de Durango was originally founded by Spanish colonists in 1563 as a mining town. (Indeed, mining remains a huge part of the wider state of Durango’s economy.) Accordingly, there’s something interesting running beneath the Cathedral Basilica of Durango: an old mine shaft. Called alternately the “Mining Tunnel” or the “Cathedral Tunnel,” the shaft was once used for actual mining; then, later on, it functioned as a secret passage. Today, it has yet another use: It houses a museum about mining.
The Paseo Túnel de Minería—the Mining Tunnel Walk—is located 32 feet below the streets of Durango City and runs nearly 1,000 feet in length. Scattered throughout, you’ll see machines, tools, and minerals pertaining to the city’s mining history; all in all, you’ll learn about four centuries of Durango mining. Like Nice’s Archaeological Crypt, it’s accessible for people with limited mobility thanks to the presence of an elevator. Tickets are $20 for adults.
Sometimes, the Mining Tunnel Walk also operates as a spookhouse. During the 2019 Halloween season, it transformed into the “Tunnel of Terror,” bringing a number of classic horror films to life with epic sets, terrifying music, and live actors.
The Lost Tunnels of Euston: London, England
When the London Underground came to Euston at the beginning of the 20th century, it did so in a slightly unexpected manner: Since two different lines owned by two different companies serviced the station, it had two separate station buildings—one for each route. In order to reduce the bother to passengers who might need to connect between the two routes, a tunnel was built to bridge the gap between the platforms, along with a ticket hall to enable an easy transfer. Additionally, another tunnel led to a bank of elevators that allowed Tube passengers to get to the Euston main line station up top, which had previously opened in 1837.
Later on, though, the two lines came under the control of a single company—and, eventually, became the two branches of the Northern Line that split from each other at Euston. It was determined that the separate station buildings were unnecessary; the main line station provided sufficient access to the platforms for both routes. So, the two original buildings were closed down in 1914. (One was demolished; the other is now an electrical substation.)
Then, in the 1960s, new changes to the Tube—including the construction of the Victoria line in 1962—made even those previous tunnels redundant. New tunnels and a bigger ticket hall were built while the old ones were closed off for several decades.
Now, though, the London Transport Museum offers tours of the long-disused tunnels (lurking in plain sight at Euston) at a price of 41.50 euros for adults. One visitor called the tunnels “a time capsule of what was happening when the platforms were closed,” featuring “posters from the 1960s [showing] films, plays, and products that were being advertised then—from Psycho to perms.” If you want to take a peek at a moment frozen in time, this tour is the way to go.
The Vienna Sewers: Vienna, Austria
Vienna’s sewer system dates back to roughly the year 100. Built by the Romans, it was highly sophisticated for its time; the Romans absolutely knew their way around an aqueduct. Like many cities, as Vienna grew, it developed a ton of sewage management issues. It wasn’t until a cholera epidemic in 1830 (the result of an influx of contaminated ground water) had killed more than 2,000 people that the system was updated—but now, it’s one of the most notable sewer systems in Europe.
In fact, it’s so notable that it was immortalized on the silver screen in 1949: That’s when the Orson Welles vehicle The Third Man was released, which culminates with a thrilling chase sequence through the tunnels of Vienna’s sewers.
Today, you can see what it’s like to run through those sewers yourself thanks to the Third Man Sewer Tour. You’ll probably get a little more out of the tour if you’re familiar with The Third Man before you go—but even if you’re not, you’ll still get an excellent rundown of the sewer’s history and architecture as well as intriguing context about life in post-war Vienna from your knowledgeable guides. Tickets are seven euros for adults.
The Odessa Catacombs: Odessa, Ukraine
The word “catacombs” may typically be associated with ossuaries and death—for instance, the Paris Catacombs were built to contain the overflow from the city’s cemeteries—but the Odessa Catacombs are a little different. They likely began as a result of the mining of the coquina—the kind of rock on which Odessa is built. In the 18th century when the Ukrainian city was founded, the coquina was literally removed from the ground and then put back on top of it in the form of houses and other buildings. Over time, more and more coquina was mined to form a sprawling network of tunnels and caves with little rhyme or reason to their layout. Now, the Odessa Catacombs run anywhere between 1,200 and 1,500 miles, making them one of the longest—if not the longest—urban labyrinths in the world.
But even though they were never used for burial purposes, they’re still plenty spooky. Indeed, stories of a young woman who went missing inside them in 2005 have circulated for years—and although it’s not clear whether these stories are fact or myth, it is all too easy to get lost in the dark down there. Just ask the teenagers who got lost in the Paris Catacombs for three days in 2017—and at just a few hundred miles, the Paris Catacombs are only a fraction of the length of the Odessa Catacombs.
However, if you choose to venture into the depths of the earth, it is important to take safety precautions: Go only where visitors are actually permitted, wear some sturdy shoes, bring a flashlight, find a guide, and, above all, tell someone where you’re going beforehand.
You probably won’t get lost…
…but it can’t hurt to let someone know where you’ll be anyway.
Just in case.