A three-metre slab covered in an unknown script stood at the mouth of the Singapore River for centuries. In 1843 an engineer blew it up to widen the harbour. One fragment survives, and the writing has never been deciphered.

On a Sunday morning in 1942 a US Navy blimp drifted out of the fog and settled onto a California street. The radio worked, the parachutes were stowed, the doors stood open. The two officers who had flown it were gone, and they have never been found.

A crater in the Turkmen desert has been burning for around fifty years, and millions of people know exactly how it started. The problem is that the story does not appear in a single document, and the geologists who worked there tell it differently.

On a clear winter morning in 1909 a brand new liner overtook a cargo steamer off the coast of South Africa, exchanged polite signals, and pulled ahead. Nobody has seen her since, and after a century of searching not one plank has ever been recovered.

A civilization of a million people left behind planned cities, covered drains, standard weights and about four thousand tiny inscriptions. After a century of work nobody can read one, and some scholars argue it was never writing at all.

For sixty years the skeletons in a frozen Himalayan pool were explained by one storm and one doomed pilgrimage. Then a genetics laboratory read their DNA and found three different groups, a thousand years apart.

On a Sunday night in 1987, a grinning rubber mask seized two Chicago television stations and spoke gibberish to a city. Federal investigators had every advantage and never came close. Nearly forty years on, not one person has been identified.

Federal and state agents searched his Georgia clinic on 16 June 2015. Three days later the autism physician was found dead in a North Carolina river, and the sheriff ruled it a suicide. His family never accepted that, and a much larger conspiracy story grew out of the case, one that investigators and fact checkers later took apart.

In August 1991 NOAA tapped into the US Navy's undersea listening network and found a signal nobody could name. It has repeated ever since, peaking every spring and autumn, from an empty patch of the South Pacific. It is fading, and no ship has ever gone to look.

Diaa al-Awady told millions of followers that food could replace medicine. Egypt revoked his licence and closed his clinics. In April 2026 he was found dead in a Dubai hotel room, and the official answer that followed convinced almost none of the people who had believed in him.

For more than a hundred years, farmers, colonial surveyors and trained field biologists have described the same small upright ape in the forests of Sumatra. There are footprint casts, hair samples and a fifteen-year camera-trap project. There is still not one photograph, and not one bone.

Between 1764 and 1767, something hunted people in the highlands of south-central France. It killed around a hundred of them, most of them women and children. A king sent his own hunters, two animals were shot and paraded as the culprit, and no one ever proved what it was.

For more than a hundred years, expeditions have pushed into the flooded forests of the Congo Basin after a large unknown animal. They came back with recordings, blurred film and hundreds of interviews. They never came back with the animal, and the dinosaur story attached to it may not have started in Africa at all.

A Hungarian count gave away his library in 1838. Inside it sat a small, fat book written in a script that matches no alphabet on earth. Nearly two centuries and a dozen rival decipherments later, not one sentence of it has been read in a way other scholars accept.

A hotel maid found the greatest electrical inventor of the age dead and penniless in a small Manhattan room. Within two days federal agents had hauled his papers away in trucks. What they took, what they returned, and what never reached Belgrade is still argued about today.

In the 1930s, bulldozers clearing jungle for banana plantations in southern Costa Rica began turning up giant stone balls, some taller than a person and weighing as much as a loaded truck. Workers dynamited many of them looking for gold inside. Nearly a century later, nobody can say for certain how they were carved so precisely, or what they were for.

At eleven on a Sunday morning in 1978, something detonated over a small iron-mining island in Newfoundland. Fuse boxes threw blue flame across rooms, televisions burst, a shed came off its foundation with the chickens inside, and two neat holes were punched into a field. American satellites built to catch nuclear tests registered the flash, and Los Alamos sent scientists. Nearly fifty years later the file is still open.

More than a hundred hollow bronze dodecahedra have been dug up across the northern Roman provinces, each pierced by holes of different sizes. Not one Roman text, inscription or image mentions them. In 2023 a field in Lincolnshire produced the finest example yet, and the mystery only deepened.

On a Victorian bridge outside Dumbarton, dogs have been going over the same few metres of parapet for seventy years, almost always on clear days, almost always long-nosed breeds. In 2005 two specialists went looking at the bridge through a dog's eyes and came back with an answer involving a smell no human can detect. The answer still has holes in it.

For more than a hundred years, travellers crossing outback Queensland have described a light that rises out of the dark, hovers above the horizon, and follows them for kilometres. In 1992 a neuroscientist built one to order, using nothing but a car and ten kilometres of empty road. Boulia was not entirely grateful.

For generations the villagers of Shiyan Beicun believed their ponds were bottomless. In 1992 four of them bought pumps to find out, and drained the water off the roof of a hand-carved hall the size of a church. Twenty-four of them have now been opened, and not one line of Chinese history mentions that they exist.

Across the highlands of northern Laos stand thousands of carved stone jars, some weighing fourteen tonnes. A French archaeologist called them tombs in the 1930s. Then the bombs fell, and it took eighty years to get back to the question.

In July 1970 a US test missile carrying radioactive cobalt came down four hundred miles inside Mexico, and the American army built a railhead, a road and a camp to take it home. What stayed behind in the Chihuahuan Desert was a story about radios that will not work. Here is the documented record, and exactly where it runs out.

Ninety-two artificial islands sit in a lagoon off Pohnpei, walled with basalt logs that weigh up to fifty tonnes each. Dating puts the first courses at around 1180 CE. Nobody has yet explained how the stone crossed the island and floated onto the reef.

On a January afternoon in 1981 a farmer in southern France heard a whistle in his garden and saw something settle on the terrace below him. Within a day gendarmes were on their knees collecting soil. Within two years a French government space agency had published the most detailed physical-trace report it would ever release. Forty-five years later, nobody agrees on what made the mark.

A 250 hectare wood on the edge of Cluj-Napoca is routinely called the most haunted forest on Earth. Behind the label sit four photographic negatives from August 1968, a circular clearing where trees will not grow, and decades of measurements that were never published. Here is what can actually be documented, and what cannot.

In late 1977, people on a small island at the mouth of the Amazon began arriving at the clinic with burns, puncture marks and stories of beams of light coming through their roofs at night. The Brazilian Air Force sent an officer to find out what was happening. Twenty years later, he broke his silence, and then he was dead.

On a September morning in 1994, the pupils of a small private school outside Harare came running in from morning break with the same impossible story. Thirty years, one Harvard psychiatrist and a shelf of crayon drawings later, nobody has explained what they saw.

On an autumn morning in 1966, a class of girls running laps on a Melbourne school oval stopped and pointed. Within minutes hundreds of students and teachers were watching a silver object sink behind the pines. By lunchtime they had been told to say nothing about it, and no official file has ever been produced.

On a clear March evening in 1997, thousands of people watched an enormous V of lights drift silently across 300 miles of Arizona sky. Two hours later a second set of lights hung over Phoenix and made the evening news. Nearly three decades on, the state's own governor is among those who say they still cannot explain what they saw.

Herodotus wrote that a Persian army marched into Egypt's Western Desert to burn an oracle and was buried alive by a sandstorm while eating lunch. Twenty-five centuries later, not one confirmed soldier of that army has ever been found. Two rival claims say they solved it, and most Egyptologists accept neither.

In 1912 a four-year-old walked away from a Louisiana swamp and vanished. Eight months later a boy was found on the road with a traveling handyman, and two mothers stood up to claim him. A court chose one of them. Ninety-two years later a DNA test proved the court had chosen wrong.

She was writing confessional singer-songwriter music in New York years before anyone called it that, and almost nobody heard it. In August 1974 she wrote a handful of calm farewell letters, packed her Volkswagen and drove out of Ann Arbor. Neither Connie Converse nor her car has ever been found.

On the morning he was due to fly to America, the lyricist of the Manic Street Preachers checked out of a London hotel and drove west, leaving his passport behind. Two weeks later his car turned up at a service station beside the Severn Bridge, battery flat, family photographs on the seat. Britain has been arguing about the rest for thirty-one years.

A crashed car on a dark New Hampshire highway. A bus driver who offered help and was turned away. Nineteen minutes later the police arrived and the driver was gone. Twenty-two years on, her phone and bank cards have never registered anywhere on earth.

She was nine years old, and at half past two in the morning she dressed, packed a bag and walked out into the rain. Drivers saw her on the highway; when one turned back she ran into the trees. A year and a half later her bag was dug up twenty-six miles away, wrapped in plastic and buried.

In April 1848 seven men, seven horses, twenty mules and fifty bullocks left the last cattle station on the Darling Downs and headed west into unmapped country. Not one of them was ever seen again. After more than a century of searching, the only object ever tied to them by name is a small brass plate stamped Ludwig Leichhardt 1848.

On a hot July morning in 2014, a German holidaymaker walked into an airport doctor's office in Bulgaria, went white, dropped his bag and bolted. Security cameras followed him over a fence, across a meadow and towards a line of trees. His wallet, phone and passport are still evidence, and he has never been seen again.

At lunchtime on a summer Sunday, the leader of a nation swam out from a beach he loved and never came back. Australia mounted one of the largest searches in its history and recovered nothing at all. Thirty eight years later a coroner finally said what had happened, and the rumours carried on anyway.

A Dutch artist left Cape Cod alone in a boat twelve and a half feet long, bound for England, as the middle chapter of a work titled In Search of the Miraculous. Radio contact stopped after three weeks. Nine months later a Spanish trawler found his empty boat drifting off Ireland, and then even the boat vanished.

Enrico Fermi placed him in the category of Galileo and Newton. In March 1938 Ettore Majorana withdrew his money, took his passport, wrote two farewell letters, cancelled them by telegram the next day, boarded the night ferry from Palermo to Naples and was never seen again. Italian prosecutors did not close the file until 2015.

He was the son of a governor, twenty-three years old, and ten miles from a mangrove coast with two empty cans strapped to his body. His father chartered a jet and sent ships, aircraft and thousands of searchers after him. They found nothing at all, and sixty years later the argument over what happened has still not ended.

On a summer evening in 1983 a fifteen-year-old flute student walked out of a music school near Piazza Navona and was never seen again. She was a citizen of Vatican City. Four decades later, after anonymous callers, two empty princely tombs and three separate investigations, her family is still asking the same question.

On Australia Day 1966 three children caught a bus to the beach and were never seen again. A stranger played with them in the sand for hours. A shopkeeper watched the eldest pay for lunch with a banknote her mother had never given her. Six decades and three excavations later, Australia still has no answer.

For years it burned across northern skies in plain sight, a slender river of mauve no textbook could explain. Then a handful of aurora chasers gave it a name, and professional science was forced to admit it had overlooked something enormous overhead.

For four centuries sailors have described whole oceans turning to cold white fire, glowing to the horizon under a dark sky. Satellites have finally caught the phenomenon in the act, yet what tips a patch of ordinary sea into a hundred thousand square kilometers of silent light remains one of the last mysteries hiding in plain sight.

On a December evening in 1997, four million Japanese children sat down to watch Pokemon. Four seconds of flashing red and blue light later, hundreds were convulsing on living-room floors. It became the most infamous television broadcast in history, and the strangest thing about it is how many of the victims had never had a seizure before, or since.

In a quiet farm town, teenage girls began to jerk, stutter and convulse one after another, with no fever, no lesion, no poison anyone could find. Doctors called it mass hysteria. The families called it something in the ground. Fifteen years later, the honest answer is still uncomfortable.

Again and again, hundreds of healthy whales swim as one onto the same fatal beaches and refuse to leave, even after rescuers drag them back to sea. Decades of science have offered sonar, solar storms, sick leaders and treacherous sand. Not one of them fully explains why the pods keep dying together.

For a few nights in April 2005, more than a thousand toads in a quiet Hamburg pond swelled to bursting and detonated, flinging their entrails a full metre across the water. A Berlin vet named a culprit nobody had imagined. The official file still reads: no satisfactory explanation.

At daybreak on 14 April 1561, the citizens of a great German city looked up and saw spheres, crosses and blood-red globes wheeling in combat above their rooftops. A single printed sheet preserved the account. Nearly five centuries later, we still argue about what they saw.

They last a thousandth of a second, blaze brighter than whole galaxies, and arrive from billions of light-years away. For years astronomers were not even sure they were real. We now know fast radio bursts exist, and one of the hardest questions in modern astronomy is what on earth is making them.

It came from another star, tumbled like nothing we had ever seen, and accelerated without a trace of exhaust. Scientists still argue about what slipped through our solar system in 2017.

He was found dead against a seawall on an Adelaide beach in 1948, his clothing stripped of every label, a scrap of Persian poetry reading it is ended sewn into a hidden pocket. For seventy-four years he had no name, only a code no one could break and a phone number no one could explain. Then DNA offered an answer, and somehow the mystery only deepened.