Voids and Vacuums

[Image: Google Maps view of Mosul Dam (bottom center) and the huge reservoir it creates].

Dexter Filkins—author of, among other things, The Forever War—has a long new piece in the first 2017 issue of The New Yorker about the impending collapse of Iraq’s Mosul Dam.

The scale of the potential disaster is mind-boggling.

If the dam ruptured, it would likely cause a catastrophe of Biblical proportions, loosing a wave as high as a hundred feet that would roll down the Tigris, swallowing everything in its path for more than a hundred miles. Large parts of Mosul would be submerged in less than three hours. Along the riverbanks, towns and cities containing the heart of Iraq’s population would be flooded; in four days, a wave as high as sixteen feet would crash into Baghdad, a city of six million people. “If there is a breach in the dam, there will be no warning,” Alwash said. “It’s a nuclear bomb with an unpredictable fuse.”

Indeed, “hundreds of thousands of people could be killed,” according to a UN report cited by Filkins.

What’s interesting from a technical perspective is why the dam is so likely to collapse. It’s a question of foundations. The dam was built, Filkins writes, on rock “interspersed with gypsum—which dissolves in contact with water. Dams built on this kind of rock are subject to a phenomenon called karstification, in which the foundation becomes shot through with voids and vacuums.”

Filling those voids with grout is now a constant job, requiring dam engineers to pump huge amounts of cementitious slurry down into the porous rock in order to replace the dissolved gypsum.

[Image: Mosul Dam spillway; photo by U.S. Army Staff Sgt. Brendan Stephens].

At one point, Filkins goes inside the dam where “engineers are engaged in what amounts to an endless struggle against nature. Using antiquated pumps as large as truck engines, they drive enormous quantities of liquid cement into the earth. Since the dam opened, in 1984, engineers working in the gallery have pumped close to a hundred thousand tons of grout—an average of ten tons a day—into the voids below.”

Finding and caulking these voids, Filkins writes, is “deeply inexact.” They are deep underground and remain unseen; they have to be inferred. The resulting process is both absurd and never-ending.

The engineers operating [the grout pumps] can’t see the voids they are filling and have no way of discerning their size or shape. A given void might be as big as a closet, or a car, or a house. It could be a single spacious cavity, requiring mounds of grout, or it could be an octopus-like tangle, with winding sub-caverns, or a hairline fracture. “We feel our way through,” [deputy director Hussein al-Jabouri] said, standing by the pump. Generally, smaller cavities require thinner grout, so Jabouri started with a milky solution and increased its thickness as the void took more. Finally, after several hours, he stopped; his intuition, aided by the pressure gauges, told him that the cavity was full. “It’s a crapshoot,” [civil engineer Azzam Alwash] told me. “There’s no X-ray vision. You stop grouting when you can’t put any more grout in a hole. It doesn’t mean the hole is gone.”

It’s hard not to think of a scene in Georges Perec’s novel Life: A User’s Manual, a scene I have written about before. There, a character named Emilio Grifalconi picks up an old, used table only to find that the support column at its center is “completely worm-eaten.” Slowly, painstakingly, operating by intuition, he fills the worm-eaten passages with a permanent adhesive, “injecting them with an almost liquid mixture of lead, alum and asbestos fiber.”

The table collapses anyway, alas, giving Grifalconi an idea: “dissolving what was left of the original wood” in order to “disclose the fabulous arborescence within, this exact record of the worms’ life inside the wooden mass: a static, mineral accumulation of all the movements that had constituted their blind existence, their undeviating single-mindedness, their obstinate itineraries; the faithful materialization of all they had eaten and digested as they forced from their dense surroundings the invisible elements needed for their survival, the explicit, visible, immeasurably disturbing image of the endless progressions that had reduced the hardest of woods to an impalpable network of crumbling galleries.”

Whether or not such a rhizomatic tangle of grout-filled chambers, linked “voids and vacuums” like subterranean grapes, could ever be uncovered and explored beneath the future ruins of a safely dismantled Mosul Dam is something I will leave for engineers.

[Image: Mosul Dam water release; photo by U.S. Army Staff Sgt. Brendan Stephens].

However, Filkins points out one possible solution that would sidestep all of this: this option, he writes, “which has lately gained currency, is to erect a ‘permanent’ seal of the existing dam wall—a mile-long concrete curtain dropped eight hundred feet into the earth.”

This would not be the only huge subterranean wall to be proposed recently: think of the “giant ice wall” under construction beneath the Fukushima nuclear power plant in Japan: “Japan is about to switch on a huge refrigeration system that will create a 1.5-km-long, underground frozen ‘wall,’ in hopes of containing the radioactive water that’s spilling out of the Fukushima nuclear power plant, which went into meltdown following the earthquake and tsunami of March 2011.”

Read more over at The New Yorker.

Deep Storage

[Image: Photo by Michele Limina, courtesy Bloomberg].

Bloomberg has a look at the subterranean warehousing strategies of the very rich, former Swiss military caves and bunkers that have been repurposed as private gold vaults.

Deep in the Swiss Alps, next to an old airstrip suitable for landing Gulfstream and Falcon jets, is a vast bunker that holds what may be one of the world’s largest stashes of gold. The entrance, protected by a guard in a bulletproof vest, is a small metal door set into a granite mountain face at the end of a narrow country lane. Behind two farther doors sits a 3.5-ton metal portal that opens only after a code is entered and an iris scan and a facial-recognition screen are performed. A maze of tunnels once used by Swiss armed forces lies within.

These “Swiss storage operations,” as the article describes them, can be seen as spatial byproducts of international financial loopholes, such as the fact that U.S. citizens “aren’t required under the U.S. Foreign Account Tax Compliance Act to declare gold stored outside financial institutions,” or that these sorts of storage firms “aren’t regulated by the Swiss financial-services regulator Finma. Nor do such companies have to report suspicious activity to Switzerland’s Money Laundering Reporting Office.”

These regulations—or, rather, the lack thereof—assume architectural form: sites of temporary burial for monetary instruments that benefit from being held securely beyond the reach of the active economy.

Now for the inevitable heist film—part Bank Job, part Zork—set in the high-tech mountain bunkers of Switzerland…

Read more over at Bloomberg.

(Thanks to @fabmass for the tip!)

Instance Gate

[Image: Malta, Instragram by BLDGBLOG].

Down in the lower levels of Valletta’s fortified walls, an old bricked-up doorway resembles something from a computer game: an oddly colored bit of masonry you would knock aside with a hammer, or a subtle wave of a wand, to make a corridor appear leading much further into the geologic depths.

The underside of Valletta, of course, is already mazed with passages, from wartime bomb shelters to church crypts, abandoned rail tunnels to hotel sub-cellars, and the entire island of Malta, made from such easily cut rock, is home to warrens of prehistoric temples and catacombs.

That entryways into the labyrinth can be found is hardly surprising; that they can look so much like a chunky, 8-bit game landscape only adds to the sense of urban mythology.

[The phrase “instance gate,” at least as I use it, comes from World of Warcraft. It implies that through a certain gate is a world that only you or your group will experience; anyone stepping through the same gate after you will, in fact, enter an entirely different space to confront an entirely different world of experiences. It’s a great metaphor.]

Urban Under

[Image: Photo by Bradley Garrett].

I’m honored to have written a preface for the new book Global Undergrounds: Exploring Cities Within, edited by Paul Dobraszczyk, Carlos López Galviz, and Bradley Garrett.

The authors document more than eighty subterranean sites, on every continent, from a nuclear bunker outside London to a secret military city buried in the ice. It is organized into thirteen chapters, by themes including “Security,” “Dwelling,” “Refuse,” and “Futures.”

[Image: Photo by Bradley Garrett].

The book is motivated by an intense desire to see: to reveal the underground circuits of utility tunnels, sanitation services, transportation networks, and everyday labor that writhe beneath the surface of the urban world. By doing so, it hopes “to foreground the connections between space and politics that converge underground.”

The editors’ collective goal was obviously more than just adventure tourism, or to produce a new gonzo collection of picturesque photographs. Rather, it was to experience these spaces firsthand whenever possible through direct exploration, whether that meant hiking down into the galleries of abandoned mines or sneaking through the tunnels of an underground prison.

[Image: Photo by Bradley Garrett].

Readers already familiar with Garrett’s work, both academic and journalistic, will know, of course, that for him infiltrating sites of public infrastructure is something of an oxymoron, given their nominal status as public space.

Nonetheless, it is often only through surreptitious means that we can truly analyze these labyrinthine systems that we have been funding all along and, today, remain so vulnerably reliant upon.

The book suggests that the peripheries of the built environment—these underspaces tucked away from view—are much more central than their physical position might suggest, and that putting them into an enlarged historical and political context is vital for understanding them.

If that sounds of interest, consider picking up a copy.

Subterranean Robotics on Other Worlds

pavonis-mons-skylight[Image: Possible cave entrance on Mars, via space.com].

There was an interesting article in last month’s issue of Air & Space about the design of subterranean robotics for exploring caves on other planets.

It primarily looks at “a robot called LEMUR, short for Limbed Excursion Mechanical Utility Robot.” LEMUR, we read, “is designed to climb the porous walls of a cave 150 million miles away, on Mars.”

lemur
[Image: The LEMUR robot in action; photo by Aaron Parness/JPL via Air & Space].

The article goes on to discuss the work of speleobiologist Penelope Boston, who you might remember from a long interview here on BLDGBLOG (originally recorded for Venue), as well as the challenges of sample-return missions, how robots might go spelunking on other planets, and more.

Check it out in full.

Schrödinger’s Speleology, or the Stalking of “Entranceless Caves”


[Image: A cave entrance in France, via Wikipedia].

I recently finished reading Last Words by Michael Koryta, a detective novel largely centered on an unmapped fictional cave system in southern Indiana, part of the great karst belt near the border with Kentucky.

One interesting thing about the novel is that this cave, known in the book as “Trapdoor,” operates on many different narrative levels. Most obviously, of course, there’s the unreliable memory of a major character suspected—yet never officially accused—of committing a murder there, where the darkness of Trapdoor’s linked subterranean spaces becomes a kind of mental model for his own inability to recall what really happened, when a woman was (apparently) murdered in the cave’s depths.

There is also a subplot, though, revealed quite late in the book, in which disguised real estate deals and obscure land trust deeds have been premised on the subterranean potential of this land snaking along the region’s old creeks and rivers, transactions inked with the belief that Trapdoor’s passages might continue beneath distant parcels; in this way, the cave comes to represent the conspiratorial intentions of people otherwise unwilling to state their true goals.

Finding the true outer limits of the cave—that is, finding the land parcels that the cave secretly connects from below—becomes coextensive with discovering the truth about what occurred underground there so many years earlier.


[Image: Cave in Venezuela, photographed by Vittorio Crobu, courtesy European Space Agency].

It was these latter parts of the novel—including a handful of plot points I won’t get into—that reminded me of notes I’d taken from a book called the Encyclopedia of Caves several years ago. That book includes a short entry written by Nevin W. Davis, called “Entranceless Caves, Discovery of.”

As Davis describes them, “entranceless caves” are like speleological versions of Schrödinger’s cat: they exist, but they have not been verified. They are real—but perhaps not. They are both in the ground and nowhere.

At times, Davis’s text is almost like a koan: “Suppose the cave is totally unknown and has no entrance,” he writes. What exactly is such a thing, and how can we account for its presence (or absence) in the landscape? After all, these are caves that have not been—and perhaps cannot ever be—located.

He goes on to describe mathematical models used to generate a probability of subterranean connection: the calculated likelihood that physically inaccessible voids might exist beneath the surface of things, linking one part of the world to another.


[Image: Cave in Mexico, photographed by Vittorio Crobu, courtesy European Space Agency].

“Another consideration in searching for caves,” Davis continues, “is entrance lifetime. Caves are long-term features under the landscape with lifetimes measured in millions of years, whereas entrances to them are fleeting features with lifetimes measured in millennia.”

Cave entrances come and go, in other words, while the caves they once led to remain. They can be covered over, woven shut by tree roots, erased.

As Davis describes it, “leaves and twigs will soon cover and block small vertical entrances. Pits less than a meter in diameter”—tiny holes that can nonetheless lead to huge systems, such as the real-life Mammoth Cave or the fictional Trapdoor—“can be totally blocked in one season. Leaves blocking a small entrance are soon followed by roots and more leaves and it is not long before all traces of an entrance are gone.”

This leads to an activity he calls “stalking the elusive entranceless cave”—which, for what it’s worth, seems like a perfect metaphor for part of Koryta’s novel, in which the book’s amnesia-stricken potential murderer undergoes hypnosis. His memory is a cave with no entrance.


[Image: Cave in Venezuela, photographed by Vittorio Crobu, courtesy European Space Agency].

In any case, there can also be “false positives,” Davis warns. These would be caves that appear to have been detected but that are not, in fact, real. A “stalker” of previously unknown caves might find herself misled by patches of melted snow, for example, or by other signs that wrongly give the impression of warm air rising from empty passages below.

“The best condition to search for snow melt,” Davis suggests, instead, “is with a new snowfall in midwinter with an overcast sky, since sunlight can also give false positives by shining through snow cover onto rocks and melting the snow. This is a tried-and-true method that has led to countless new caves.” It’s cave-discovery weather.

In essence, this is a process of reading the landscape: interpreting its surface features in order to gain knowledge of these other, deeper dimensions.


[Image: An artificially enlarged entrance to Carlsbad Caverns; Instagram by BLDGBLOG].

The next entry in the Encyclopedia is also worth reading; it is simply called “Entrances,” by William B. White. “Some caves,” White writes, continuing the strangely existential thread of Davis’s work, “may have no entrances at all.”

White adds a new category here, what he calls the “concealed entrance.”

At least from an architectural point of view, what’s interesting is that this allows White and other speleologists to challenge the idea of there being a clean dividing line between inside and outside, between a cave and the Earth’s surface.

Instead, he suggests, a cave’s entrance should actually be thought of as a transition: the “cave entrance zone,” White writes, “is, in effect, a continuous sequence of microclimates,” one that eventually leads to a point at which there is no direct access to sunlight or to rainfall.

It is only at that point that you are truly “inside” the Earth. You have transitioned to the great interior.


[Image: Photographer unknown; image via Discovery Communications].

Briefly, White also points out that cave entrances are not only unstable in the temporal sense—as Davis mentioned, cave entrances can completely disappear over time.

However, they are also unstable spatially: that is, they can physically migrate through the landscape over thousands, or even tens, of years.

Due to continual rockfall, for example, a cave entrance “not only migrates deeper into the hill but also migrates upward as rocks break away,” Davis writes. This can potentially push a cave entrance dozens and dozens of feet from its original location, while the cave itself remains stationary. Imagine a mouth migrating across your body while your stomach stands still.

Of course, this also means that an entrance to a given cave system can abruptly migrate onto someone else’s property, or that it can even pop open, suddenly and dramatically changing the value of a particular piece of land.

The next thing you know, following an unusually intense summer rainstorm, you own the entrance to a cave.

[Image: A salt cave in Israel; image via Wikipedia].

Which brings us back to Michael Koryta’s novel. There, an unexpected opening into the unstable depths of Indiana’s fictional Trapdoor complex changes the lives of many characters not just for the worse, but for the tragic.

The cave, as Koryta depicts it, is a relentless and unsympathetic thing, a space always shifting, growing organically but not alive, invisible yet ubiquitous, moving beneath the surface of the landscape, connecting parcels of land, as well as the lives—and deaths—of the characters who thought they were just idly passing time above.

(Vaguely related: Life on the Subsurface: An Interview with Penelope Boston).

Subterranean Singapore

oil
[Image: A “Cavern Breathing Unit” from Subterranean Singapore by Finbarr Fallon, Bartlett School of Architecture, Unit 24].

Here is another project from my reviews the other week at the Bartlett School of Architecture; this one is called Subterranean Singapore, and it is by Finbarr Fallon, produced for Unit 24, which is taught by Penelope Haralambidou, Simon Kennedy, and Michael Tite.


[Image: “Concept Breathing Towers” from Subterranean Singapore by Finbarr Fallon, Bartlett School of Architecture, Unit 24].

Subterranean Singapore is presented as a speculative look at massive underground residential development in the city-state of Singapore over the next few decades.


[Images: Glimpses of a “high grade recreational space within an inflatable cave unit,” from Subterranean Singapore by Finbarr Fallon, Bartlett School of Architecture, Unit 24].

The city has run out of room to expand into the sea, and is thus forced to look downward, into the depths of the continental shelf, excavating beneath the surface of the city and heading partially out below the seabed.


[Image: From Subterranean Singapore by Finbarr Fallon, Bartlett School of Architecture, Unit 24].

As Fallon describes it, the project explores “the city-state of Singapore’s subterranean ambitions to suggest an imagined masterplan and spatial typology for deep-level underground living. While it may seem utopian to imagine that extensive deep living will become viable, the pressures of chronic land scarcity in Singapore may necessitate this outcome.”


[Image: The “Subterranean Development Institute: Designing Your Underground Future,” from Subterranean Singapore by Finbarr Fallon, Bartlett School of Architecture, Unit 24].

The construction process is kicked off with great imperial fanfare, involving a parade of excavation machines and robot carving arms marching their way forward through clouds of confetti. There is even a celebratory pamphlet.


[Images: From Subterranean Singapore by Finbarr Fallon, Bartlett School of Architecture, Unit 24].

The idea is not entirely science fiction, of course: Singapore is already excavating huge oil-storage facilities underground, and nearby Hong Kong is actively experimenting with the design and implementation of entire underground infrastructural zones.


[Images: From Subterranean Singapore by Finbarr Fallon, Bartlett School of Architecture, Unit 24].

For Fallon, however, such a proposal cannot be divorced from the question of who will be able to afford these spaces of underground luxury—complete with fish ponds, spas, and the soothing presence of exotic mechanical animals meant to bring an ironic touch of the natural world to those below.


[Image: A light-well looking down at Subterranean Singapore by Finbarr Fallon, Bartlett School of Architecture, Unit 24].

Let alone, of course, the question of human labor. Who, after all, will physically construct these things? Whose backs will be broken?


[Image: From Subterranean Singapore by Finbarr Fallon, Bartlett School of Architecture, Unit 24].

The accompanying film—in fact, the film is the core of the proposal—suggests that not everyone is pleased to see this triumphant underground utopia take root beneath Singapore, and hacker-saboteurs appear to take things into their own hands.

While the plot itself is not unusually complex, many of the images successfully wed the cinematic and the architectural, and were worth posting here.


[Images: From Subterranean Singapore by Finbarr Fallon, Bartlett School of Architecture, Unit 24].

With any luck, I’ll post a few more student projects here in the days to come; for now, don’t miss Matthew Turner’s project for a “New London Law Court.”

The Soft Spot

geoborder[Image: Close-up of the 2010 State Geologic Map of California].

An interesting story published last month in the L.A. Times explored the so-called “sweet spot” for digging tunnels along the California/Mexico border.

“Go too far west,” reporter Jason Song explained, “and the ground will be sandy and potentially soggy from the water of the Pacific Ocean. That could lead to flooding, which wouldn’t be good for the drug business. Too far east and you’ll hit a dead end of hard mountain rock.”

However, Song continues, “in a strip of land that runs between roughly the Tijuana airport and the Otay Mesa neighborhood in San Diego, there’s a sweet spot of sandstone and volcanic ash that isn’t as damp as the oceanic earth and not as unyielding as stone.”

More accurately speaking, then, it is less a sweet spot than it is a soft one, a location of potential porosity where two nations await subterranean connection. It is all a question of geology, in other words—or the drug tunnel as landscape design operation.

border[Image: Nogales/Nogales, via Google Maps].

With the very obvious caveat that this next article is set along the Arizona/Mexico border, and not in the San Diego neighborhood of Otay Mesa, it is nonetheless worth drawing attention back to an interesting article by Adam Higginbotham, written in 2012 for Bloomberg, called “The Narco Tunnels of Nogales.”

There, Higginbotham describes a world of abandoned hotel rooms in Mexico linked, by tunnel, to parking spots in the United States; of streets subsiding into otherwise unknown narco-excavations running beneath; and of an entire apartment building on the U.S. side of the border whose strategic value is only revealed later once drug tunnels begin to converge in the ground beneath it.

Here, too, though, Higginbotham also refers to “a peculiar alignment of geography and geology,” noting that the ground conditions themselves are particularly amenable to the production of cross-border subterranea.

However, the article also suggests that “the shared infrastructure of a city”—that is, Nogales, Arizona, and its international counterpart, Nogales, Mexico—already, in a sense, implies this sort of otherwise illicit connectivity. It is literally built into the fabric of each metropolis:

When the monsoons begin each summer, the rain that falls on Mexico is funneled downhill, gathering speed and force as it reaches the U.S. In the 1930s, in an attempt to control the torrent of water, U.S. engineers converted the natural arroyos in Nogales into a pair of culverts that now lie beneath two of the city’s main downtown streets, Morley Avenue and Grand Avenue. Beginning in Mexico, and running beneath the border before emerging a mile into the U.S., the huge tunnels—large enough to drive a car through—created an underground link between the two cities, and access to a network of subterranean passages beneath both that has never been fully mapped.

This rhizomatic tangle of pipes, tubes, and tunnels—only some of which are official parts of the region’s hydrological infrastructure—results in surreal events of opportunistic spelunking whereby “kids would materialize suddenly from the drainage grates,” or “you would see a sewer plate come up in the middle of the street, and five people would come up and run.”

Briefly, I’m reminded of a great anecdote from Jon Calame’s and Esther Charlesworth’s book Divided Cities, where the split metropolis of Nicosia, Cyprus, is revealed to be connected from below, served by a shared sewage plant “where all the sewage from both sides of the city is treated.” The authors interview the a local waste manager, who jokes that “the city is divided above ground but unified below.”

In any case, the full article is worth a read, but a tactical geological map revealing sites of likely future tunneling would be a genuinely fascinating artifact to see. I have to assume that ICE or Homeland Securitylet alone the cartels—already have such a thing.

(L.A. Times article originally spotted via Nate Berg).

The Voids Beneath

sinkhole[Image: Drone footage of a Cornwall garden sinkhole, via the BBC].

One of the peculiar pleasures of reading Subterranea, a magazine published by Subterranea Britannica, is catching up on British sinkhole news.

In more or less every issue, there will be tales of such things as “a mysterious collapse in a garden behind a 19th-century house,” that turns out to be a shaft leading down into a forgotten sand mine, or of “abandoned chalk mine sites” heavily eroding in winter rain storms, “resulting in roof-falls.”

“As most chalk mines are at relatively shallow depth,” Subterranea reports, “these roof-falls migrate upwards to break [the] surface as ‘crown holes’ or craters, which in the said winter [of 2013/2014] have been appearing in lawns and driveways, and even under houses, newly built in chalk districts.”

The earth deceptively hollow, the landscape around you actually a ceiling for spaces beneath.

Worryingly, many of these mines and underground quarries are difficult, if not impossible, to locate, as insufficient regulation combined with shabby documentation practices mean that there could be abandoned underground workings you might never be aware of hiding beneath your own property—until next winter’s rains kick in, that is, or the next, when you can look forward to staring out at the grass and shrubbery, with growing angst, waiting for sinkholes to appear. Rain becomes a kind of cave-finding technology.

Even in the heart of London, the underworld beckons. Last Spring, Subterranea reminds us, “a woman and her shopping trolley rather suddenly disappeared into a four metres deep hole in North End Road, Fulham.” The culprit? It “appears to have been a disused under-street coal cellar.”

Perhaps the most incredible recent example, however, comes from the town of Scorrier, in Cornwall.

shaft[Image: Photo courtesy The Sun].

There, a “deep mine shaft has appeared” beneath the patio of a house in the process of being prepped for sale. “The shaft drops approximately 300 feet deep to water but could be four or five times deeper [!] below that,” Subterranea reports. It “is a remnant of Cornwall’s tin mining industry in the 18th century.”

It is a straight vertical shaft, more like a rectangular well, yawning open behind the house.

And there are many more of these mines and quarries, still waiting to be discovered: “As mines closed,” we read, “many [mining companies] put very large blocks of timber, often old railway sleepers, across shafts and backfilled them, thinking this would be safe. Gradually all evidence of the engine houses and covered shafts disappeared from view and memory and in the past builders assumed there was nothing there. Had they consulted old maps they would have known about the shaft. The timbers rotted over the years and collapses like this often happen after long periods of rain, which they have had in this area.”

There’s something both uncanny and compelling about the idea that, with seasons of increased rainfall due to climate change, the nation’s mining industry might stage an unsettling reappearance, bursting open in subterranean splendor to swallow the surface world whole.

Think of it as an industrial-historical variation on the El Niño rains in Los Angeles—where huge storms were suspected of “unearthing more skeletal human remains” in the parched hills outside the city—only here given the horror movie ambience of murderous voids opening up beneath houses, making their abyssal presence felt after long winter nights of darkness and endless rain.

In any case, consider joining Subterranea Britannica for a subscription to Subterranea for more sinkhole news.

Secret Tunnels of England

The London Fortean Society, of all people, will be hosting a talk called “Secret Tunnels of England: Folklore and Fact” by Antony Clayton, author of the fascinating book Subterranean City: Beneath the Streets of London, on March 9. “So-called secret tunnels are a subject of perennial interest,” we read. “Are there really labyrinths of hidden passageways under our ancient buildings, towns and cities, or are these tunnel tales another seam of England’s rich folklore?” See, for example, BLDGBLOG’s earlier look at the Peterborough tunnels. There is still time to get on a waiting list for tickets. For what it’s worth, I also referred to Clayton’s book in my recent essay for The Daily Beast about the Hatton Garden heist. (Event originally spotted via @urbigenous).