While many discoveries have been made regarding underground structures and even whole cities like Derinkuyu, there are plenty of mysteries surrounding them. After all, there’s only so much that detailed research and careful excavation can reveal about a civilization that has long since vanished. Or at the very least, the civilization has changed to the point of no longer resembling its former self making it harder to understand its past compared to the present. So unless we had a time machine on hand, which hasn't been invented yet and probably won’t be in the near future, some things may never truly be understood.

But while a majority of the things we know about ancient civilizations comes from years of research and excavations that have proven similar conclusions that are almost regarded as fact, some things are harder to prove than others. This is either due to a lack of evidence to prove the claim in the first place, or because the claim is so far-fetched that no one can take it seriously. Though just because it’s outrageous doesn’t make it any less strange. Whether it’s actual discoveries or anecdotal tales, these examples demonstrate some of the strangest things that have supposedly been found beneath the earth.

25 Underground Cherkizovsky Market Town

While plenty of crazy things happen in Russia that always make headlines in the media, this story might surpass them. In Moscow, a police raid revealed an entire community of people that were living underground. The explanation for this, according to Cracked, is that, “When the famous and immigrant-friendly Cherkizovsky Market closed down” its residents moved under the streets of Moscow where they continued to live and operate their businesses. Thus, it was more or less an underground sweatshop for illegal immigrants. Plus, there were other venues such as “A movie theater, a bar, and a cafe” Cracked states.

24 Crump Cave Coffins

In terms of its history, the deep South may seem exotic to those who are drawn to its deep green forests mysterious swamps and controversial history. For reasons such as this, some interesting tales have come out of this region. One such example comes from Alabama where a series of empty coffins were found in the late 1800s that, “Appeared to be hollowed out by fire, then chiseled with stone or copper tools” according to ThoughtCo. After they were discovered by Rev. William N. Crump, these coffins were shipped to the Smithsonian Institute and were apparently lost in the process.

23 Rio Castor Woman

Moving to something more fantastic, there is an interesting anecdote that’s been floating around certain websites about a strange woman. Found by an unnamed explorer in “A tunnel near Rio Castor” according to ThoughtCo, which is supposedly located in Brazil, this woman claimed to be “2,500 years old” even though she looked roughly 20 years of age. This, in turn, ties into a popular theory that there might be an underground realm beneath Brazil itself, though there is no absolute proof of that. Yet Brazil does have amazing subterranean wonders such as mysterious "Smooth-walled tunnels” Earth Touch News states.

22 Concepiao Underground Vehicles

In another example relating to the theory that there’s an underground city somewhere in Brazil, ThoughtCo describes an incident where an old man “Visited a vast underground city where strange vehicles darted back and forth”. Supposedly, this incident happened in a place called Concepiao which doesn't seem to be an actual location in Brazil. However, it could be a mispronunciation of Conceição which is a district in the state of Paraíba on Brazil’s northeast side. It also doesn’t help that the account doesn’t describe what the vehicles actually look like, making this story more dubious in terms of the truth.

21 Underground Rincon Saucers

Always a favorite among conspiracies, UFOs or flying saucers as they’re unofficially called tend to show up just about everywhere. This even includes stories about a possible underground city in Brazil, such as this one which comes from a place called Rincon (which doesn’t seem to be real). According to ThoughtCo, two explorers found a tunnel entrance where they witnessed “Luminous flying saucers going in and out”. Like the other two stories that are supposedly from Brazil, this one’s many anecdotal in nature with no physical proof behind the claim such as pictures or even reputable sources that support it.

20 Missing Submarines

Because the San Andreas Fault rests along two tectonic plates, it’s often at the epicenter of many earthquakes in California. This has even led to some interesting speculations, including the notion that the San Andreas Fault is actually made up of “Unsupported chambers that are in the process of collapsing” as claimed by ThoughtCo. Supposedly, this claim came from an account made by a US Navy officer who explored these chambers in a submarine (despite other submarines supposedly vanishing in them). The account in turn was published in a magazine that doesn’t seem to exist, or at least not anymore.

19 A Mysterious Shrine under the Grand Canyon

Because places like Brazil are considerably exotic due to its tropical landscape and being the home of many ancient civilizations, it might spark the imagination of those who think something more amazing lies beneath its surface that’s just waiting to be discovered. Yet the United States has its own considerably exotic locations, such as the Grand Canyon. A vast area that’s protected by the federal government, how could anyone not potentially imagine something more to it? Take, for example, the idea that there is “A shrine containing a Buddha-like idol” supposedly in the Grand Canyon as claimed by ThoughtCo.

18 A Mummy Crypt in America

If a Buddha statue in the Grand Canyon doesn’t sound like a far-fetched idea, then how about a crypt full of mummies? “Wrapped in a bark fabric” according to ThoughtCo, this crypt and the Buddha statue are just one of many things supposedly discovered by two archeologists from the Smithsonian Institute. This proved to them that Ancient Egypt influenced North America’s early history, though this idea has been disproven in similar cases or is at least up for debate. Plus, the only proof of this supposed expedition is in a “1909 edition of the Arizona Gazette” according to Gizmodo.

17 Strange Stone Tablets

For those who’ve ever wondered where people got the idea that Ancient Egyptians somehow influenced the early history of North America, it arguably began with stories like the Arizona Gazette article which detailed findings such as stone tablets with “Egyptian-like hieroglyphics” carved onto them as claimed by ThoughtCo. Then in the 1970s, traces of tobacco were found on the mummified remains for the pharaoh Ramesses II. Now since tobacco was assumed to have originated from the New World, this was seen as “Proof that there was pre-Columbian contact between Egypt and South America” according to Hall of Maat.

16 Rooms Full of Mysterious Artifacts

In addition to the tablets and the mummies, there were supposedly rooms full of artifacts in the Grand Canyon “Such as weapons and copper instruments of a kind that have never been known to be native to the Americas” as described by ThoughtCo. Now it should be emphasized that the article where these discoveries were mentioned in included no pictures, let alone credentials of the two archeologists who were identified as Professor S. A. Jordan and adventurer G. E. Kinkaid. In fact, “No record exists of Kincaid or Professor Jordan within the Smithsonian's Department of Anthropology” as stated by Gizmodo.

15 An Underground Chamber with Branching Pathways

Though the Arizona Gazette article is real, it was published anonymously. So it’s easy to assume this was a “Purely fictional invention of the anonymous writer who concocted it” as determined by Skeptoid. After all, pulp-fiction stories were popular in the 1900s and the discovery of Tutankhamun’s tomb certainly got lots of people excited including their imaginations. But while things like the Buddha statue and crypt certainly seem invented, one of the other discoveries this article claimed was “A mammoth chamber about 1,480 feet underground” with branching pathways according to ThoughtCo which sounds slightly more believable but not much.

14 Marble Corridors

A giant cave that lies thousands of feet below the Earth’s surface is one thing, but underground corridors made of marble? That sounds unlikely depending on who built them. In this case, they were supposedly found by an expedition that occurred on Mt. Tsurugi. Located in Japan, this mountain has a number of strange stories associated with it “Including a giant serpent and the Ark of the Covenant” according to the Nishi-Awa Tourism Area’s official website. So it wouldn’t be surprising if this expedition that happened in the 1930s and then stopped is yet another story of dubious origin.

13 California Cave Music

Given the primordial fear that caves naturally induce when we traverse them, it would seem additionally scary to hear music on top of that. Such a thing seemingly happened to “A couple from Bishop, California,” according to ThoughtCo, where they found a tunnel that suddenly produced water from several crevasses. While they were able to escape just fine, they recalled hearing music right after. Like the Grand Canyon story, this one comes from an actual published source despite its questionable authority in terms of truthfulness. Specifically, it is from a “1963 issue of SEARCH magazine” as claimed by Subterranean Bases.

12 West Virginia Cavern Hieroglyphics

While it’s not as majestic as the Grand Canyon, West Virginia has a similar story about a subterranean discovery that’s questionable in nature. As described by ThoughtCo, “Workers found some caverns with strange hieroglyphics written on the walls”. Now the term “Hieroglyphics” would imply they are Ancient Egyptian, which would certainly make this part of the string of claims that Ancient Egyptians were somehow present in North America before it was officially discovered by European explorers. But as stated before, there’s little to no proof of this despite exceptions with other cultures such as Vikings who established settlements in Canada.

11 A Ball of Fat found underground

Of the various chores we have to do in our daily lives, no one likes to deal with the plumbing in any shape or form. Whether they are sinks, toilets, or showers/bathtubs, these things shouldn’t be left unchecked in general. Otherwise, something like the above picture could happen. Even worse, one could have a “Fatberg” to deal with. To explain, this was the term used to describe a large “Ball of fat” that was discovered in the sewers beneath the Kingston area of London, England, according to Cracked. Made from different kinds of waste, it’s not the only one.

10 Network of Shelters

When it comes to any construction job, there’s going to be a lot of digging involved to create the necessary foundation for a building in general. But sometimes, they’ll come across something unexpected. For instance, a construction crew in San Jose “Found over 70 vaults” beneath the area they were developing for a “New soccer arena” according to Cracked. The purpose of these is a mystery, though one might assume they were created to provide shelter in case of warfare. Yet some things found inside these shelters included “A gaping void bigger than an Olympic-size swimming pool” Cracked states.

9 Underground Drawings

Now here’s a story that’s difficult to swallow, yet fascinatingly so: it begins with a “1956 bestselling book called The Third Eye, which is an allegedly autobiographical account by a man named Tuesday Lobsang Rampa” according to Mysterious Universe. In this book, he details a trip to Lhasa, the capital of Tibet, where he found a number of strange things underneath the Dalai Lama’s palace including drawings of unknown symbols and diagrams for mysterious machines. While this sounds like the plot for a story written by H. P. Lovecraft, it does demonstrate how the exoticness of places like Tibet can spark imaginations.

8 Obsidian Sarcophagi

Apart from the mysterious drawings, Rampa also describes finding “Three sarcophagi apparently made of a smooth black stone similar to obsidian” according to Mysterious Universe. But like the Arizona Gazette article, Rampa’s autobiographical account of these events in The Third Eye has been questioned by skeptics. In fact, an actual detective was hired to figure the truth out. What he found was that Tuesday Lobsang Rampa was actually an alias used by Cyril Hoskin, “A British-born son of a plumber who lived in Ireland in the mid-1950s and moved to Canada in the 1960s” according to Skepdic.com.

7 Gold Tablets Showing Human History

From one fantastic story to another, we jump from the exotic realm of Tibet to the more mundane city of Los Angeles. Home to a number of famous celebrities and entertainment businesses, this place has its share of outrageous claims. One such instance occurred with the publication of the “1934 edition of the LA Times” according to Mysterious Universe in which “A geophysical engineer by the name of G. Warren Shufelt” claimed to have discovered an underground city beneath Los Angeles. In it, Shufelt found gold tablets that detailed all of human history which he supposedly photographed via x-rays.

6 Underground Lizard People

A popular conspiracy theory, the Lizard People are said to be creatures who either secretly live among us or mysteriously disappeared long ago. In relation to the Los Angeles story, Shufelt claimed they “Set up a vast underground cavern system under the Los Angeles area thousands of years ago” Mysterious Universe says. Yet in the time since the LA Times article where this claim was published, no further evidence has been found. Thus, it’s believed to be a hoax and yet Gizmodo argues this story is “A predecessor to the reptilian urban legends that currently run rampant on the internet”.