What is history's greatest mystery?

When the crowds have gone and jackdaws strut high above on the megalithic lintels, I can bask in the quiet majesty of Stonehenge. It is 40 years since I first directed an excavation there. In that time, we have learnt more about the monument and the people who erected it than I imagined possible. But can we at last say why Stonehenge was built? I would say no. The more we learn, the greater the mystery.

We build our picture of the ancient past from things we dig up and things we imagine. The oldest stories about Stonehenge tell how a wizard flew the stones across from Ireland. You can still make out the imprint of a heel where the devil flung one of the megaliths at a friar. On another stone, water, reddened by algae, pools like sacrificed maidens’ blood.

Historical inquiry, finding no record of Stonehenge’s construction, sought to pin the achievement on known ancient peoples from other countries: Greeks, Romans and early medieval Danes. Such speculation was stilled in 1901, when the first scientific excavation at the site exposed nothing that wasn’t already recognised as the tools and debris of prehistoric Britons. Nonetheless, the structure’s extraordinary design and materials meant that the possibility of Mediterranean connections – even a Greek architect – survived into the 1960s. But by then, most archaeologists had embraced the modern view: Stonehenge was entirely the creation of indigenous Neolithic peoples.

Historical inquiry, finding no record of Stonehenge’s construction, sought to pin the achievement on known ancient peoples from other countries

The argument then moved from who built it to what sort of society was responsible for it. Was it the ultimate symbol of a highly ranked culture – a chiefdom, perhaps – where the big monuments were expressions of status, power and means of control? Or was it a focal point in an egalitarian world that needed places for people to come together from wide areas, to trade, socialise and engage in communal rituals and ceremonies?

If these theories about a complex monument with a suitably complex history are more helpful than the one-line ideas that are popular in the media – it was a sex symbol, a computer, an observatory or an amplifier – still none get close to truly explaining Stonehenge.

Developments in archaeology have swung the balance of inquiry heavily in favour of evidence from the times – things we dig up. With new scientific innovations, more excavations and more archaeologists asking more questions, we now have significantly more data, as well as more types of data, than I could have imagined when I stood by my trench 40 years ago. However, the result is not that we can now answer the question: why Stonehenge? It’s in fact the opposite. The more we learn, the more we realise how astonishingly technically accomplished – and downright strange – Stonehenge really was.

“How Grand!” wrote Sir Richard Colt Hoare, a British antiquary and archaeologist, when contemplating Stonehenge in 1810. “How Wonderful! How Incomprehensible!”

One of archaeology’s great achievements of the past two centuries has been to prove Hoare right: Stonehenge truly is incomprehensible.

Mike Pitts is an archaeologist and author. His most recent book is Digging Up Britain: Ten Discoveries, a Million Years of History (Thames and Hudson, 2019)

Could Roman soldiers have reached China?

Chosen by Catherine Nixey

The sound alone would have been terrifying. A Roman legion contained around 5,000 men; 5,000 men had 10,000 feet. Each of those 10,000 feet was shod in caligae, the famous Roman hobnailed military sandals. The sound of just one of these shoes slapping against stone signalled to the empire’s enemies that trouble was on its way; the cacophony made by 10,000 is all but unthinkable.

Yet it is not the sound of Roman legions that, at the distance of two millennia, is the most compelling – it is their silences. One such silence enveloped the legions of Crassus who fought against the Parthian empire at the battle of Carrhae in what is now Turkey.

Crassus should never have stepped onto the battlefield. He was wealthy, so much so that the famously affluent Croesus paled in comparison to him. But during combat, gold is no substitute for an affinity with sharpened steel. The omens for the battle had been terrible – and, it transpired, devastatingly accurate. By the end of that dark day in 53 BC, Crassus’s son had been beheaded, with the decapitated head paraded on a spear before his father. Crassus, his heart broken, lost his own head a little later.

The battle would become infamous as one of Rome’s worst ever military defeats. And the thousands of Roman soldiers who hadn’t lost their lives were taken captive and transported east. Although the Roman poet Horace suggested the remnants of the legions had married Parthians, their true fate remained shrouded in mystery.

• What was the Roman Empire’s greatest defeat? It might be Teutoburg Forest in AD 9

But in the mid-20th century, Homer Dubs, an expert in Chinese studies based at Oxford, argued that they might have travelled further east than originally thought – potentially several thousand miles further. A few years after the battle of Carrhae, during the siege of a city in China, some mercenaries exhibited military behaviour that hadn’t been seen before in the country: they interlocked their shields so closely against enemy fire that they resembled a ‘fish scale’. The term is unique in Chinese literature. However, interlocking shields was one of the Roman army’s signature moves, known as the testudo formation.

At around the same time in China, a city named Liqian (the ancient Chinese word for ‘Rome’) was founded. Was this the final destination of those Roman soldiers who had survived the battle of Carrhae? The theory is still unproven, but perhaps one day we will learn where the staccato beat of their caligae finally came to a halt.

Catherine Nixey’s books include The Darkening Age: The Christian Destruction of the Classical World (Macmillan, 2017)

Where is Cleopatra’s tomb?

Chosen by Lloyd Llewellyn-Jones

Antony and Cleopatra’s doomed love story has captivated the world for centuries. The Roman general, beset by grief and shame following his final defeat during the battle of Alexandria at the hands of his foe, Octavian, turned his sword on himself upon hearing the (false) news that Cleopatra had died.

However, his lover still lived: she had merely hidden herself in her tomb following Octavian’s victory. Antony was then transported to the mausoleum, where he finally succumbed to his wounds in the embrace of his queen.

Rather than fall under Roman domination, Cleopatra, surrounded by sumptuous pearls, gold, silver and countless Egyptian treasures, killed herself on 12 August 30 BC – possibly by the bite of a cobra (or asp), a powerful emblem of pharaonic divinity. She was 39 years old. Cleopatra’s corpse was mummified and, on Octavian’s orders, interred beside Antony. Some 16 centuries later, Shakespeare, Antony and Cleopatra’s playwright, pronounced: “No grave upon the Earth shall clip in it a pair so famous.”

The location of Cleopatra’s tomb has remained an enigma for hundreds of years

The location of Cleopatra’s tomb has remained an enigma for hundreds of years. If it was as grand as the Roman reports would have it, the tomb should have left its mark on the archaeology of Alexandria, Cleopatra’s great capital city. But no trace has ever been found. Alexandria and its environs have typically attracted less attention than the more ancient sites strung along the Nile, and the city itself has become increasingly difficult to excavate: today, most of ancient Alexandria is submerged under approximately 20 feet of water.

• The face of Cleopatra: was she really so beautiful?

However, in 2006 it seemed a breakthrough had occurred. Zahi Hawass, then secretary-general of Egypt’s Supreme Council of Antiquities, announced that Cleopatra’s tomb had been located at a ruined temple dedicated to Osiris (the deity of death and resurrection) near the town of Taposiris Magna, 30 miles west of Alexandria – although, confusingly, Hawass would later deny ever making the announcement. Archaeologist Kathleen Martinez received permission to dig at the ancient temple, yet after a decade of excavation and hundreds of minor finds, including pottery and even skeletal remains, the temple has not yielded a secret tomb. Martinez remains convinced, however, that Cleopatra’s body is there.

If – and that’s a big if – Cleopatra’s tomb is discovered, then the archaeological world will shake. The find would even outshine that of Tutankhamun’s remains. But there’s a fly in the ointment. And that’s that when archaeologists pin their hopes of discovery to fleeting textual references – in Cleopatra’s case, those created by hostile Roman historians – the results are, inevitably, disappointing.

Lloyd Llewellyn-Jones is professor of ancient history at Cardiff University

What was the Feejee Mermaid?

Chosen by Karen Jones

“Roll up, roll up! See the amazing Feejee mermaid!” In the early 1840s, these tantalising words rang out almost daily from PT Barnum’s American Museum – home to a motley collection of exotic animals, people with unusual physical characteristics (such as the diminutive General Tom Thumb, who was just 25 inches tall) and other obscure exhibits. And the Feejee mermaid was certainly worthy of its place in this bizarre depository.

Legends of mermaids had enraptured sailors and landlubbers alike for centuries. In Greek mythology, sirens lured seafarers to their deaths, and Christopher Columbus claimed he’d witnessed mermaids swimming near Hispaniola while exploring the New World. Perhaps most famously, Hans Christian Andersen made the enigmatic creature the star of his fairy tale The Little Mermaid.

• The myths of the Victorian freak show

In the early 19th century, the legend took a sensational turn with the unveiling of a 3-foot-long mummified creature, half-humanoid and half-aquatic, reportedly captured by Japanese sailors off Fiji. It was transported to Europe by Dutch merchants, acquired in 1822 by American mariner Samuel Edes for the princely sum of $6,000, and then continued to change hands until it was leased by showman extraordinaire PT Barnum, who gave it top billing at his New York museum in 1842.

With the benefit of hindsight, the fakery of the Feejee mermaid seems obvious. After all, South Pacific fishermen were known to cobble together chimeras from fish tails and ape or monkey torsos to impress visiting seafarers, not to mention moneyed European collectors who were keen to populate their ‘cabinets of curiosity’ with expensive trinkets, each more exotic and eclectic than the last. But at the time, many people wanted to believe such creatures might be real – and, even if the Feejee mermaid was a forgery, they wanted to gawk at it anyway.

In an age of global exploration, new species were being continually discovered and classified. And many of these animals appeared almost fantastical, with creatures like the platypus becoming focal points for intense debate surrounding their unusual physical characteristics. If these strange critters could be real, some reasoned, then why not mermaids?

With the benefit of hindsight, the fakery of the Feejee mermaid seems obvious

Meanwhile, in the 19th century the general public was enthralled by questions of the human-animal divide, prompted in large part by the works of Charles Darwin and others who were versed in evolutionary theory. Equally, the popularity of Barnum’s museum spoke to a broader fascination with freak shows – circuses that specialised in ‘deviant’ bodies, from bearded ladies to fearsome wolf men – that was an entertainment staple of the 19th-century city.

There is another twist to this tale: what happened to the Feejee mermaid? After its exhibition at Barnum’s museum (and a travelling tour of the southern USA), it disappeared from public view. Various incarnations appeared in sideshow museums and freak shows in later years, only to be exposed as fakes of the original fake. Perhaps this curious cryptozoological artefact is languishing in someone’s attic, waiting to be discovered.

Karen Jones is professor of history at the University of Kent. Her latest book is Calamity: The Many Lives of Calamity Jane (Yale, 2020)

Who was the architect of Anne Boleyn’s downfall?

Chosen by Tracy Borman

For Anne Boleyn, the morning of 2 May 1536 started out as any other. Watching a game of tennis at Greenwich Palace, she began considering placing a bet on one of the players – until a messenger arrived and told her that, by order of the king, she must present herself before the Privy Council at once. Even though Anne could not have guessed that she was about to face charges of adultery and – even more shockingly – incest, his words must have filled her with dread.

Anne’s marriage to Henry VIII had been falling apart for months, thanks largely to her failure to give him the son he craved. Her husband could barely stand the sight of her, and eagle-eyed courtiers noticed that in private he “shrank from her”. Then, in January 1536, Anne miscarried for the third time. Even though she had only been 14 weeks’ pregnant, it was rumoured her attendants could tell it had been a ‘male child’ she carried. For Henry, this was the last straw: he was desperate to be freed from the shackles of his marriage. But did he devise the means, or was that down to his ‘fixer’, Thomas Cromwell?

Cromwell had a strong motive of his own to get rid of Anne. Although they had started out as allies, by 1536 they were enemies, and Anne had made it clear “she would like to see his head off his shoulders”. It was his neck or hers.

Cromwell led the investigation into Anne’s private life and compiled the ‘evidence’ of her adultery with five men – her own brother George included – as well as a plot to murder the king. He was also instrumental in preparing for Anne’s trial, which was held at the Tower on 15 May and was so heavily weighted against her that the guilty verdict was assured.

Cromwell had a strong motive of his own to get rid of Anne. Although they had started out as allies, by 1536 they were enemies

According to the imperial ambassador Eustace Chapuys, Cromwell boasted that he “had planned and brought about the whole affair”. But had he been acting on Henry’s orders, or did the king have something less extreme in mind – another annulment, perhaps?

• The final days of Anne Boyleyn: why did she die?

There is, of course, another possibility: that Anne really was guilty of adultery, incest and treason. She was certainly a notorious flirt who loved to surround herself with adoring male courtiers. Her friendship with Henry Norris was particularly close, and she once made the fateful remark that he “looked to dead men’s shoes” – in other words, he hoped the king would die so that he could wed her. But most of the counts of adultery have been convincingly disproved, and it seems unlikely that someone of Anne’s political guile would risk everything for a thoughtless affair (or several of them).

What – or who – was really behind Anne’s downfall has been the subject of furious debate among historians ever since. But unless fresh evidence comes to light, we will probably never know the answer. Perhaps that’s why we’re still so fascinated by her story, almost 500 years after her death.

Tracy Borman is a historian and broadcaster. Her books include Henry VIII and the Men Who Made Him (Hodder & Stoughton, 2018)

Did Agatha Christie engineer her own disappearance?

Chosen by Dominic Sandbrook

Never has there been a more intriguing case of life imitating art than the disappearance of Agatha Christie, the ‘Queen of Crime’.

On the evening of 3 December 1926, Christie – at this point, one of Britain’s most promising popular writers, with six books to her name – was at her home in Sunningdale, Berkshire. She had just emerged from a blazing row with her husband, Archie, who had recently asked her for a divorce. She went upstairs to kiss her seven-year-old daughter goodnight. Then, she got behind the wheel of her Morris Cowley, started the engine – and disappeared.

What followed was a media sensation. Amid a blizzard of headlines, the police mobilised a thousand officers to help with the search. Christie’s rival, Dorothy L Sayers, visited her house to look for clues, and Sir Arthur Conan Doyle consulted a medium for advice from the spirit world. One Daily Express front page alluded to the twists of the bizarre case: “CLUES IN THE RIDDLE OF MRS CHRISTIE – Hatless Woman Met on the Downs – 5 AM INCIDENT – Helped by a Man to Start Her Car.” Christie herself could not have invented a more thrilling mystery.

For 10 days, there was no sign of her. Then, on 14 December, Christie was found in Harrogate’s genteel Swan Hydro Hotel, where she had checked in under an assumed name. The writer had participated in the hotel’s bridge and dancing programmes for days, and when she was recognised at last, she claimed to have lost her memory. Perhaps the strangest thing of all, though, was her choice of false name: Neele. For, as she knew, her husband had been having an affair – and his lover’s surname was Neele.

• The golden age of murder: Agatha Christie and the Detection Club

Precisely what happened will never be known. Doctors confirmed Christie’s claim that she had lost her memory, but some people insisted it was a publicity stunt. And fascination with the case continues to this day. One of Christie’s biographers thinks she staged the disappearance to humiliate her husband; another believes she suffered a severe nervous breakdown.

Christie never spoke of the incident again; in her autobiography, she did not afford the episode a single word. Her most enduring mystery, then, is rooted in fact rather than fiction.

Dominic Sandbrook is a historian, author and broadcaster. His most recent book is Who Dares Wins: Britain, 1979–1982 (Allen Lane, 2019)

Where did the Ninth Legion meet its doom?

Chosen by Miles Russell

The disappearance of the Ninth Legion, one of four elite military units occupying Britain in the aftermath of the Roman invasion of AD 43, has puzzled historians for centuries. In AD 108 they were recorded rebuilding the legionary fortress of York. However, 12 years later they vanished, with their name notably absent from all subsequent military listings. One popular theory concerning their fate – augmented by Rosemary Sutcliffe’s bestselling 1954 novel The Eagle of the Ninth, as well as two cinematic offerings, Centurion (2010) and The Eagle (2011) – is that the 5,000 soldiers of the Ninth marched north from York to suppress a rebellion, only to be ambushed and cut to pieces in the swirling mists of Caledonia.

It is easy to understand the appeal of such a story, where disadvantaged, poorly equipped British warriors inflicted a humiliating defeat upon a well-trained, heavily-armoured professional army; a clash between an over-confident imperial power and an indigenous people who refused to accept that they were beaten, where the underdog emerged victorious.

Historians, however, have doubted the validity of this hypothesis in recent years, suggesting it is more likely the Ninth was butchered somewhere on the eastern frontier of the Roman empire, having been transferred there sometime in the early second century. Unfortunately, there is not a shred of evidence to support this. The last datable artefact that relates to the Ninth is the inscription in York on the Fortress Gate, which includes the personal titles of Emperor Trajan – titles that have been dated to AD 108. In contrast, evidence for a possible transfer to the eastern frontier comprises just a few tiles, shards of pottery and a bronze pendant, all bearing the mark of the Ninth Legion, found at Nijmegen in the Netherlands. Although these do indeed show that the legion (or at least a part of it) was deployed here, it seems they derive from the early AD 80s, when Roman soldiers were sent from Britain by the Emperor Domitian to fight the Chatti, a particularly troublesome Germanic tribe.

Historians suggest it is more likely the Ninth was butchered somewhere on the eastern frontier of the Roman empire

Given the absence of evidence elsewhere in the empire, then, is there anything in Britain that suggests Rosemary Sutcliffe was right after all, and that the Ninth Legion was indeed lost in Britain during active service?

The Roman historian Fronto, writing in the AD 160s, noted that in the reign of Emperor Hadrian (AD 117–38), large numbers of Roman soldiers were slain by the British. While the full extent of these losses remains unknown, they must have been significant for Fronto to have mentioned them. The Augustan History, compiled in the fourth century, observed that when Hadrian became emperor, “The Britons could not be kept under Roman control”. Meanwhile, a tombstone recovered from Ferentinum, Italy states that emergency reinforcements of more than 3,000 men were rushed to the island on “the British Expedition” early in Hadrian’s reign. Hadrian himself came to Britain in AD 122 to “correct many faults” and instruct the Romans to build his eponymous wall. He also brought a new legion, the Sixth, with him. The fact that they took up residence in York seems to indicate that the great loss of personnel noted by Fronto had indeed occurred within the ranks of the Ninth, who had formerly been based here.

• What happened to Britain’s lost Roman legion?

Until more conclusive evidence is found to illuminate the final days of the Ninth, we can only speculate as to what happened to them. However, it seems likely that somewhere in northern Britain, there’s a corner of a forgotten field that is for ever Rome.

Miles Russell is a senior lecturer in prehistoric and Roman archaeology at Bournemouth University

What disaster struck the Franklin Expedition?

Chosen by Andrew Lambert

In 1845, two British warships, HMS Erebus and HMS Terror, with 129 officers and men on board, sailed under the command of Captain Sir John Franklin into the Canadian Arctic. It was generally assumed they were attempting to complete the fabled North-West Passage, connecting the Atlantic to the Pacific, but in actuality their mission was to reach the magnetic north pole and conduct an overwinter series of magnetic observations as part of a global research project.

The warships reached their destination in September 1846. However, three men had lost their lives (modern autopsies indicate tuberculosis was to blame) during the journey, and even more died during the next 18 months, including Franklin, but curiously no causes of death can be determined. In April 1848 the remaining crew abandoned their ships, which were imprisoned by thick ice off King William Island, an outcrop in the Canadian Arctic Archipelago.

The only surviving written record of the expedition is a brief note stating the survivors’ intention to reach Back river – more than 1,000 miles away. However, in the face of limited food supplies, an inability to hunt what scant resources they came across during the journey, sub-zero temperatures and extremely difficult terrain, their desperate march descended into large-scale cannibalism at two separate locations (which was witnessed by Inuit hunters). The entire expedition perished less than halfway to safety.

The only surviving written record of the expedition is a brief note stating the survivors’ intention to reach Back river

Over the following decade, 13 search and rescue missions were dispatched from Britain and America, and in 1859 a sledge expedition finally reached Victory Point on King William Island. Here, the officers’ final message was discovered, as well as a boat containing incomplete skeletons. Despite clear evidence, the crew’s cannibalism was concealed, and a statue was erected in London to commemorate Franklin’s ‘discovery’ of the North-West Passage.

• Finding HMS Terror: the Franklin Expedition and making sense of the past

The official line on the fate of the Franklin expedition went largely unchallenged until just six years ago, when Canadian archaeologists located and visited the remains of both Terror and Erebus. Terror, they discovered, had been successfully navigated south from Victory Point, and Erebus probably drifted south with the melting ice and sank without a crew on board.

Despite the discoveries of the two wrecks, the reason why the ships were abandoned – and why so many men died before the survivors decided to make for Back river – remains a mystery. The expedition’s paperwork, which could contain the answer to this puzzle, is unlikely to have survived 170 years below the waves. Perhaps this enigma will always go unsolved, with the crew’s secrets lost to the icy water.

Andrew Lambert is professor of naval history at King’s College London. His most recent book is Seapower States (Yale, 2018)

Why did medieval Europeans dance themselves to death?

Chosen by Helen Carr

In the town of Strasbourg, 1518, a woman named Frau Troffea left her house and weaved her way down a narrow street. Then, she began to dance, not to music but to her own wild and furious tune, succumbing to a madness that quickly spread. Others heard this silent call, and soon almost 400 people were cavorting through the town, a frenzy of contorting and twisting limbs. The crowd – now a spinning mass of bodies – had been seized by an overwhelming compulsion to dance, without rest, food or water.

This was not the first time such an epidemic, known as a ‘Dancing Plague’, afflicted Europe. Accounts from 1374 describe a similar situation in the Rhine: “First of all they fell foaming to the ground; then they got up again and danced themselves to death.”

The strange phenomenon has never been fully explained. Historically, it was attributed to demonic influence, or even heresy. Nineteenth-century historians turned to science and attempted to diagnose the dancers with Sydenham’s chorea or chorea minor, a disorder characterised by rapid, uncoordinated jerking movements primarily affecting the face, hands and feet. In more recent decades, environmental catalysts have also been investigated, including the ingestion of ergot: a type of fungus containing psychotropic properties that was famously used to account for the hysterical behaviour in Salem, New England, that resulted in the mass witch trials of 1692–93.

Another explanation, first offered by psychologists and then taken up by historian John Waller, is also persuasive: the dancing plague was the result of mass psychogenic illness. This type of disorder is triggered by emotional or mental stress, and the medieval period was rife with war, plague and famine. In the 14th century, flooding in the Rhine saw water levels rise to 34 feet, submerging Strasbourg and causing devastation, which was followed by disease and starvation. And in the decade prior to the 1518 dance, Strasbourg was ravaged by plague, famine and a severe outbreak of syphilis, leaving its people in despair. Could these terrible hardships be, then, the reason why sufferers of the dancing plague seemed to dissociate from their bodies and become lost in a strange reverie, bruised, bloody and cavorting without rest, sometimes for weeks at a time?

Another explanation is also persuasive: the dancing plague was the result of mass psychogenic illness

Indeed, this almighty compulsion to dance could be the result of a type of post-traumatic stress disorder. But this means of processing their dire circumstances was dangerous: many dancers died of exhaustion, dehydration or starvation. Others eventually fell out of their trance-like states and were submerged once more in reality.

However, while these curious cases may shed new light on the ambiguous history of the psychological response to extreme physical and emotional stress, we still cannot know for sure why the dancing plagues of the 14th and 16th centuries swept through parts of Europe. For now, at least, the real reason people danced through the streets of Strasbourg or spun and swayed at the banks of the Rhine remains an enigma.

Helen Carr is a medieval historian and TV producer. Her podcast, Hidden Histories, is available to stream at Acast.com

What secrets do the kofun tombs hold?

Chosen by Christopher Harding

They are Japan’s answer to Egypt’s pyramids: enormous ‘old tombs’ (kofun) built by many hundreds of workers at a time to house the remains of – we think – the very greatest of kings. The first small kofun began appearing across Japan in c250 AD. Chambers were sunk into the ground, then built up at the sides using stone and finally enclosed over the top to create a great mound. By the fifth century, kofun that were hundreds of metres in width and length were being constructed.

We know quite a lot about kofun. The basic design came from the Korean peninsula. So this was yet another element of Japanese culture with roots in mainland Asia, along with everything from rice agriculture and bronze-working to a writing system, music, dance, Buddhism and fine clothes.

Inside each of the kofun that have been excavated so far, archaeologists have typically found a wooden coffin buried alongside precious objects, ranging from bronze mirrors to iron armour to finely wrought swords. Outside, on the slopes of the mounds, people sometimes placed terracotta figurines as boundary markers. Known as haniwa, their designs can be incredibly intricate, including dancers, female shamans, warriors, horses, boats and birds.

However, what we don’t know about the largest and grandest of these burial mounds – the Daisen Kofun – is the answer to the most important question of all: who is inside? This kofun, located in present-day Osaka, was constructed in the fifth century. Incorporating three moats, it is nearly half a kilometre long, 300 metres wide and more than 30 metres tall; in fact, this particular kofun is so large that its grandeur and distinctive keyhole shape can only be fully appreciated from the air. Given all this, we can be fairly sure that no ordinary person lies beneath.

• Searching for the pharaohs: where are the tombs of Ancient Egypt’s missing kings and queens?

But in Japan, it’s forbidden to excavate any kofun over a certain size and created in the shape of a keyhole, as it’s believed that these are the resting places not just of great kings, but of divine emperors. To venture inside these burial chambers would be sacrilege – or would it? These spectacular kofun are perhaps a necessary mystery: to open them up, only to find something inside that calls into question the history of the world’s oldest monarchy, is a risk that the tombs’ overseers – the Imperial Household Agency – simply cannot afford to take.

Christopher Harding is a senior lecturer in Asian history at the University of Edinburgh

Read on for the next 10 mysteries…