Advances in scientific technology have progressed so much in recent years that it's almost hard to believe there are still so many unsolved mysteries out there waiting to be cracked.
In the last few decades, things like carbon dating has made it possible to continue where Charles Darwin left off and help solve life's greatest all-time mystery - why and how we are here. Having the technology, at long last, to analyse ancient artifacts has allowed scientists to pin down when a dinosaur may have lived, how it moved and sometimes even what it could have eaten.
Outside the world of palaeontology, years of research into subjects like astronomy, physics and medicine have managed to shed light on some of the greatest mysteries in humankind. Science has managed to blow all previously held assumptions out of the water when it comes things like gravity, quantum physics and - going back even further - whether or not the Earth is round. In light of these kinds of ground-breaking discoveries, you might think the following historical cases would be a piece of cake to figure out!
As it happens, these historical head-scratchers have been equally enigmatic and have all endured as much speculation and theories over the years as gravity or the first ever fossil. When you consider what we have already been able to achieve in such a short space of time, you would think that science would have had a crack at these historical riddles, but no such luck!
These are 15 of history's biggest mysteries, and ones that scientists are still desperate to solve.
15 Jimmy Hoffa's Remains
The disappearance of the infamous union leader and once convicted criminal, Jimmy Hoffa, has fascinated forensics and the American public for more than 40 years. Hoffa went missing in Michigan in 1975, never to be seen again.
Although Jimmy Hoffa was declared legally dead in 1982, many sources have attested to his whereabouts. Hitman Richard Kuklinski - known as 'The Iceman' - claims to have killed Hoffa and dumped his body at a scrap yard. A more recent testimony in 2015 from former mobster, Philip Moscato, claims that Hoffa was shot dead before being stuffed into a 55 gallon drum and buried near the Pulaski Skyway in New Jersey.
Whatever Hoffa's true fate was, it certainly had the ring of The Sopranos to it. Yeesh.
14 The Devil's Footprints
When town residents in 19th century Southern Devon awoke to find a single line of hoof-like prints in the snow, they came to many interesting conclusions - before eventually settling on it being the work of the devil. Right.
Oddly, the marks continued in the same single pattern for a distance of 40 miles. According to some, this could have been the work of a kangaroo (with a lot of stamina), a balloon that had been trailing a horseshoe-shaped rope behind it (um, what?) or naturally, the Devil's footprints! National newspapers at the time could not a find a "satisfactory solution" to explain the mysterious prints, as no known animal or man could (or would!) walk this distance overnight in a single line. Expect M. Night Shyamalan's big-screen retelling any day now.
13 The 'Mary Celeste'
The infamous "ghost ship" that is the Mary Celeste has dumbfounded scientists for more than a century. The ship was discovered drifting hundreds of miles East of Azores by the crew of another cargo vessel in 1872. The ship was eerily found with no passengers or crew members and many possessions were left behind.
A long-held theory was that the crew had abandoned ship due to a fire, but there was no sign of an explosion or any charred parts of the ship. Determined to prove this theory in 2006, a scientist at University College London constructed a replica of the hold in the Mary Celeste to simulate an explosion by using paper instead of barrels. What resulted was a "pressure wave" explosion that left no soot or scorch marks behind. If this is true, the noise of the supposedly safe blast will have spooked the crew enough to abandon ship.
This may rule out a more exciting theory - a 1965 episode of Doctor Who that saw the passengers vacate the ship when the Daleks turned up. As good an explanation as any!
12 Cleopatra's Tomb
It is widely believed that the Egyptian queen was buried with her lover, Marc Anthony after their deaths in 30 BC, and the whereabouts of said tomb has been a mystery for over 2,000 years. Many excavations have been carried out in a temple near Alexandria, containing a number of tombs dating back to Cleopatra's reign, but the lover's tomb was not among them.
Some have suggested that the tomb was never built as a grand monument, owing to the circumstances surrounding Cleopatra's death (it is still debated whether Cleopatra was murdered or committed suicide). Most likely because her relationship with Marc Anthony was mired in scandal, her resting place may have never been recorded and deemed insignificant.
11 The 'Copper Scroll' Treasure
One of the 980-something "Dead Sea Scrolls" found in Qumran by archaeologists in the 1950s, the ancient Copper Scroll is probably the most fascinating and elusive of the lot. Unlike the other scrolls that were written in papyrus or parchment, this was carved (as its name suggests) entirely into copper.
The scrolls are said to date back almost 2,000 years, at a time when there were many revolts against the Roman Empire. Scientists believe it was hidden to prevent it being captured by the Roman forces - and when you learn what its engravings are, it's not hard to see why. The Copper scroll is basically a grand treasure map, listing a vast number of gold and silver items and where to find them. Whether these treasures are real or not is still a mystery. The hunt is on!
10 The City of Atlantis
Many popular books and films have given us a glimpse into the supposed world of Atlantis, but is there any fact hidden amongst the fiction? The city of Atlantis originated with a story created by Plato, which told of prehistoric Athenians battling it out against the inhabitants of Atlantis, which ended in the city's defeat and disappearance to the bottom of the Atlantic Ocean.
As with most stories, many have tried to find truth in it, with some speculations that the story of Atlantis has eerie links with real-life events in Greek history. One in particular involving the Minoan civilization living in Crete between 2700 and 1420 BC. Archaeologists discovered that after suffering immeasurable damage due to a volcano eruption in Greece, the Minoan people were possibly forced to join with the mainland people. A song of...water and lava, rather than ice and fire, then?
9 Babylon's Hanging Gardens
To earn the title "Wonder of the World," you have to be pretty show stopping. The Hanging Gardens of Babylon appear to be "purty" and all, but as it turns out, history may have exaggerated a tad. Ancient writers and sources from around 450 BC claim the gardens to have been a magnificent world wonder, and one that supposedly scaled heights of over 300 feet and 56 miles in length.
Modern archaeological visits to the ancient city's site in Iraq have found little evidence of gardens matching this description, and may never do so. This could either be because, the gardens never actually existed or that the impressive structure was destroyed by earthquakes or war damage.
8 The "Mothman"
In what almost sounds like a prequel to Stranger Things, four American teens from West Virginia reportedly saw a scary bird-like creature on a dark November night in 1966. The creepy winged-beast was said to have possessed glowing red eyes and large bat-like wings.
The local sheriff held a press conference the next day and the monster was henceforth dubbed "Mothman" after the Batman TV series of the time. A book by John Keel that discussed the strange goings on in the Ohio Valley believed the Mothman could have been linked to a bridge collapse in 1967 that killed 46 people (including Mothman witnesses!). None of this would be half as creepy if they had found "Butterflyman" instead.
7 Panxian Caves
The Panxian Dadong caves in Southern China are an incredible sight in and of themselves, but it is what has been found inside them that has come to bewilder scientists. In the late 1990s, the remains of prehistoric rhinos and gigantic stegodons were found in the caves - which is puzzling, as the caves are over then 5,000 feet above sea level.
The idea that creatures of their stature (and ones that typically grazed alone) could have lived and survived in these caves is baffling. Experts in palaeontology have theorised that carnivores may have killed and dragged their bodies into the cave. Other evidence points to human interference, as some bones showed signs of being burned and crushed, presumably by primitive tools made from stone.
6 The "Screaming Mummy"
Mummies are pretty creepy anyway, let alone screaming ones. Hauntingly, the discovery of a mummified human with a pained expression was discovered in 1886 and has puzzled theorists ever since.
During the mummification process, organs are usually removed from the body - but this mummy had their organs intact. This has led some experts to believe that the victim was maybe poisoned or buried alive. What makes the "screaming" theory a possibility is that some believe the mummy to be the son of Pharaoh Ramses III, who was suspected of plotting to kill his father and likely met a painful end. A less exciting explanation could be that the jaw simply hung open as the deceased victim's head rolled back, but where's the fun in that?
5 Eternally Burning Lamps
Even the best "extra-life" lightbulbs money can buy eventually die on you, so the idea of lamps burning in the middle ages without ever being snuffed out is insanely impressive. These mysterious everlasting lamps were sealed in tombs to help guide the dead into the afterlife. The freaky part is the fact that when these tombs were re-opened thousands of years later, the lamps were still burning bright (without any fuel!).
Unfortunately, some treated these ever-burning lamps with suspicion and destroyed many lamps for fear that they held a supernatural curse. Since the first known discovery of these eternal lamps, many have cropped up around the world from England and North America to Egypt and China. There could be hundreds more tombs waiting to be uncovered that may hold more of these magical lamps. For now, experts are still very much in the dark about it.
4 The First "Flying Saucer" Sighting
Many sci-fi authors and screenwriters can thank Kenneth Arnold, as he was the first person to witness a mysterious flying object in the sky - the subsequent report of which lit the torch for our worldwide fascination with UFOs.
Arnold spotted nine "bat-wing shaped" objects flying overhead near the Cascade Mountains of Washington on a June afternoon in 1947. Describing his sighting to a reporter, he said that the strange objects moved like a saucer would if you “skipped it across the water.”
When the story broke, an editor coined the term "flying saucers" and a sci-fi phenomenon was born. Today, many fanatics make it their life's work to seek out flying objects in the sky - all based on one eyewitness account almost 70 years ago! Steven Spielberg ain't complaining.
3 The Fate Of The Ark Of The Covenant
When Jerusalem was attacked by a Babylonian army in 587 BC, they destroyed the First Temple. Not only did this lay waste to a sacred place of worship for the Jewish people, the temple had become rid of the Ark of the Covenant - the chest that held the tablets of the Ten Commandments.
Ancient scholars suggested that the Ark was either taken back to Babylon or hidden long before the city was ransacked. Centuries of stories have proclaimed to know the true whereabouts of the Ark - claiming it resides in Ethiopia today, whilst others say it was hidden by divine intervention and will not reveal itself until a messiah arrives. Yeah, science may not have a chance with this one.
2 Jack The Ripper
More than a century after the brutal murders of five women in the East end of London, experts are still desperate to identify the iconic shadowy killer in a top hat and cape. The case of Jack the Ripper has inspired countless works of film and literature over the years, but no real evidence has been uncovered to put a face to the mysterious serial killer.
The name Jack the Ripper originated when a series of letters were sent to the police in an effort to taunt them about the Ripper's whereabouts. Whether they were actually written by the Ripper himself has been the subject of debate for decades. Some even proclaim that it could have been a woman. (Jackie the Ripper doesn't sound any cozier...).
1 The Turin Shroud
People are always cropping up in the news reporting to have found the image of Jesus in a potato chip or some other ridiculous object, but this ancient length of linen cloth is the one to have garnered the most worldwide attention when it comes to resembling holy figures.
The debate over the appearance and exact age of the shroud has been steeped in controversy for centuries. Some Christians believe it to be the material used in the burial wrapping of Jesus. Others believe it to be a painting, and some - a photograph. Since different forms of analysis - including radiocarbon dating and spectroscopy - have placed the age of the shroud between 300 BC and 1390 AD, even the experts can't decide whether the shroud is a medieval fake or the genuine article.