In 1971 a man who called himself Dan Cooper and later was better known as D. B. Cooper bought a plane ticket flying from Portland to Seattle. Witnesses say he ordered a bourbon and soda and looked like an average businessman in his 40s, wearing a black suit and with a black attaché case in his hand.But he was no ordinary businessman.

In that little black suitcase, he had a bomb and he let the crew know that he was going to detonate it unless he was given $200,000, 4 parachutes and a fuel truck standing by in Seattle to refuel the aircraft upon arrival. The passengers actually weren’t aware of what was going on and were told there would be a delay because of technical difficulties.When the plane landed, the passengers were let out and D. B. Cooper was given his money.

Then he and a couple of members of the crew boarded the refueled aircraft again. After taking off, Cooper collected his things and jumped out of the plane.To this day the FBI couldn’t find out who that man was and many people don’t believe that D. B. Cooper survived as traces of the ransom money were found along the banks of the Columbia River in 1980.

The Library of Alexandria was one of the largest and most significant libraries of the ancient world. It was part of the research institute at Alexandria in Egypt called Mouseion. Until the Library of Alexandria, most other libraries were regional and the one in Egypt aimed to be universal, having knowledge from all over the world.Various sources estimate different numbers of books in the library.

The number ranges from 200k to 700k but we will probably never know how big the library’s collection was, nor what treasures and knowledge it contained as it was destroyed and we know about it just from written records as there are no archeological remains of it.Historians suggest that the library had rhetoric, law, epic, tragedy, comedy, lyric poetry, history, medicine, mathematics, and natural science books that could have told us so much about how people saw the world then, but it all perished such a long time ago that it is unlikely any developments would happen now.

The identity of Jack The Ripper is a topic up for speculation even a century and half later. He was a serial killer active in London in the late 19th century and at the time he was called the Whitechapel Murderer and Leather Apron in the press.As the identity of the killer is unknown and because the crime rate was high, it is hard to tell which victims belonged to the same person, but there are 5 who are attributed to Jack the Ripper.Most of the reports done by the police were destroyed during World War II, but from what remains, we are able to learn that more than 2,000 people were interviewed, "upwards of 300" people were investigated, and 80 people were detained; however, there was no conclusion to who the killer was.

Attila was a constant threat to the Western and Eastern Roman Empires. Attila was winning territories and was not that far from taking over the known world in the 5th century. He invaded Italy in 452 and was headed towards Rome.The then emperor thought that this matter could be negotiated and sent Gennadius Avienus, one of the consuls of 450, Memmius Aemilius Trygetius, the former urban prefect, and Leo I, the pope to talk this sacking matter over.

There are no records of what the negotiators said to Attila, but they definitely did something right as the ruler of the Huns withdrew and the credit for that was given to the Pope. Even if there is a possibility that Leo I documented the conversation and the manuscripts hide in the Vatican archives, they are not open to the public.

The Isabella Stewart Gardner Museum houses some significant examples from ancient Rome, Medieval Europe, Renaissance Italy, Asia, the Islamic world, and 19th-century France and America. You can find works of Titian, Rembrandt, Michelangelo, Raphael, Botticelli, Manet and Degas.In 1990, the museum was robbed. This theft is actually considered to be the biggest one in art history.

Two thieves came in pretending to be police officers and managed to take 13 paintings worth half a billion dollars.Among the works was one of Johannes Vermeer’s works The Concert (c. 1664), and Rembrandt’s only known seascape The Storm On The Sea Of Galilee (1633). The paintings never resurfaced and the Vermeer one is actually considered to be the most valuable unrecovered painting at over $200 million.

The Bronze Age is a historical period that lasted from about 3300 BCE to 1200 BCE. It is called that because people discovered that they could combine metals and create bronze. It was a rich period with various civilizations, like the Egyptians or the Babylonians, thriving and evolving their culture with the new tools they could build.However, for no apparent reason, in a span of a few decades, the culture collapsed and that is when the new historic period called The Dark Ages began.

Historians guess that it can be explained by all the disasters that can happen happening at the same time, like drought, famine, roving marauders and others. Because the civilizations were so dependent on each other, they also collapsed together.There are theories about Sea Peoples who are said to have attacked major cities by burning them down, but not all historians believe they actually existed, although there is a relief on the walls of Ramses III’s temple at Medinet Habu that shows a sea battle.

Genghis Khan is considered to be the founder of Mongol Empire and was its first emperor. He conquered so much land that it was the biggest contiguous empire the world has ever seen, expanding even after his death. It actually covered more than 16% of the earth's landmass and 25 percent of the world's population live within its borders.The emperor died during the fall of Yinchuan, which is now a part of China. The reasons of his death are unclear as well as the place he was buried in.

Researchers think it might be somewhere in the vicinity of the Mongol sacred mountain of Burkhan Khaldun in current northeastern Mongolia. According to the legend, this was exactly what Genghis Khan wanted: to be buried without signs and be brought back to Mongolia.

On Christmas Eve in 1945, a house in which The Sodder family lived was engulfed by a huge fire. The family was celebrating and the two parents with their nine out of ten children were in the residency when the tragedy took place. The fire started in the middle of the night while the family was asleep. When the parents realized what was happening, they took four of their children out and escaped. They were calling for the rest of the children, but nobody answered and they couldn’t go up the stairs to check on them because the staircase was already in flames.

The fire department arrived just the day after as the was a shortage of firefighters due to war. They claimed that no bodies were found in the ashes and some say that they lied to calm down the parents. Chief F.J. Morris believed the fire was hot enough to burn the bodies completely.There was no investigation done, so the official reason for the fire was said to be because of faulty wiring.

After the family had time to think, they didn’t believe it was true. Also, their telephone lines were cut, the trucks had been tampered with and it seemed that someone had tried to make it as hard as possible for the family to get help. What is more, the mom didn’t believe Chief F. J. Morris because other things like kitchen appliances were still recognizable, so how could the bodies have not survived the fire?There are a lot of discrepancies in the case and that leads people to believe that the fire was not an accident and that the missing children were kidnapped.

The Amber Room was not just a room but a piece of art. It had amber walls backed with gold leaf and mirrors, with gemstones and carvings. It was more than 55 square meters (590 square feet) in size and contained over 6 tons (13,000 pounds) of amber.When Germany invaded Russia during the Second World War, they disassembled the room and transported it to Königsberg (current Kaliningrad). Later the city was bombed and since the war, nobody has seen the Amber Room, which is still being searched for to this day.In the photo you can see the autochrome made in 1917 by Andrei Andreyevich Zeest of the original Amber Room in Tsarskoye Selo, Catherine Palace. The monument in the middle is dedicated to Friedrich the Great, King of Prussia.

One of Australia’s most mysterious unsolved cases is the Tamám Shud case, also known as the Mystery of the Somerton Man. He was found on 1 December 1948 on the Somerton Park beach. He has never been identified and his cause of death also was uncertain as there were no obvious injuries. He had blood in his stomach, which indicates a presence of poison, but tests didn’t show anything.What makes the case even creepier is that in the man’s pocket investigators found a piece of paper that read “Tamám Shud” which in Persian means “it is finished.”

These are the words from the final page of a 12th century poetry book Rubaiyat of Omar Khayyám.The book from which the paper was ripped out was found and it had two phone numbers and a code that hasn’t been cracked since. That leads some people to believe the man was a spy who knew too much and needed to be eliminated. Others suggest that it was a suicide because of a broken heart.While the case is strange and nothing makes sense, there is a slight chance of finding out the identity of the man as in May last year, the Somerton Man’s body was exhumed to put its DNA into the database.

The Ark of The Covenant was a chest made of pure gold that contained the tablets with the Ten Commandments. According to the Book of Exodus, God himself instructed Moses to build it during his 40-day stay upon Mount Sinai.The Ark is mentioned in the Bible several times and that it was kept safe in Solomon’s temple until the Babylonians attacked Jerusalem and destroyed the temple in 587 BC. Since then there are no records in the Books of Kings and Chronicles of where the Ark went.There are mentions that it might have been hidden before the Babylonians arrived and there is the Church of Our Lady Mary of Zion which claims they have it, but nothing is confirmed.

The way Edgar Allen Poe met his end is extremely suspicious. The writer was noticed wandering the streets in Baltimore, Maryland seemingly delirious and in great distress. He was taken to the hospital and after a few days, he died.His friend Joseph E. Snodgrass came to visit Poe and he couldn’t recognize the writer. He was disheveled, wearing ill-fitting clothes, which the friend believed not to be his own. Poe was not able to explain what happened to him as he remained in the delirious state for the remainder of his stay at the hospital. Before his death, he repeatedly called out the name "Reynolds" but nobody had a clue what that meant.What is also mysterious is that there are no records about the cause of Poe’s death.

Theories suggest that his blood sugar was too low or maybe the delirium was a result of a failed attempt of suicide by drugs. Snodgrass believed that alcohol was the poison that killed his friend.Some theorists think he was a victim of a crime. Gangs would force random people to vote for certain politicians they worked for. And made them do it several times. They often would get the victim drunk by force to make them comply.Unfortunately, no detective was as smart as Poe’s literature characters and could solve this mystery, at least not yet.

Anne Frank was hiding from the Nazis with the help of Miep Gies. The girl and her family lived secretly in an attic apartment that is now known as the Secret Annex for 2 years until they were found by the Gestapo and sent to concentration camps.Apparently they were anonymously tipped, but the identity of the person was never confirmed. There are several suspects, but historians don’t rule out that the Nazis found the hiding spot by accident as well. This secret might be already buried with the people who knew anything.

The Alcatraz Federal Penitentiary was a maximum security prison in the US until 1963. It was not only known for being impossible to escape due to security and the prison being on an island, but for the cruel and inhumane conditions that led people to insanity.That is why people still took their chances and tried to escape anyway. Most of them were caught, shot or drowned but Frank Morris, John Anglin, and his brother Clarence Anglin actually disappeared. However, it is unclear if their mission was successful as they were not found during the intensive search immediately after noticing their cell was empty or any time later when the search expanded globally.

The original Irish Crown Jewels were made for the Sovereign and Grand Master of the Order of St Patrick and King Of Great Britain and of Ireland George III. In 1831, they were replaced by new ones presented by William IV.The last time the regalia were worn by Lord Lieutenant, The 7th Earl of Aberdeen, was on 15 March 1907, and after that they were put in the safe. The safe was opened on 11 June when Sir Arthur Vicars wanted to show the jewels to a visitor. Then, four days before the visit of King Edward VII and Queen Alexandra to the Irish International Exhibition, on July 6, the jewels were no longer in their usual place.The investigation was long and Scotland Yard even offered rewards for information. The author of Sherlock Holmes, Arthur Conan Doyle, offered his help. The police went as far as taking leads from psychics, but nothing gave results. Most probably they will never be found as often stolen jewelry is sold broken into pieces.

The Voynich manuscript is an illustrated codex from the early 15th century that nobody can decipher because it doesn’t correspond with any known writing system. The illustrations show various herbs, diagrams suggestive of astronomy or astrology, as well as apparent recipes and pictures of naked women.Both the illustrations and the text are confusing, but that hasn't stopped researchers from having hypotheses about what is the purpose of the manuscript. Overall the manuscript resembles something similar to a medicine book, but it might well be a hoax.

In 1483, King of England Edward IV died and at that time, only two of his sons were still alive. Usually that meant that the eldest son would take the throne, but Edward V of England and Richard of Shrewsbury, Duke of York, 12 and 9 years old respectively, were lodged in the Tower of London by their father’s brother who then became Richard III.There are no records about the fate of the children and it is widely believed that they were murdered. Maybe by Richard III, maybe by their maternal uncle, the Duke of Buckingham, or brother-in-law King Henry VII or anyone else, it’s up for speculation. Some are more optimistic and say they might have escaped. Whatever the case might be, they’re definitely dead by now and it would be nearly impossible to know what happened more than half of a millennia ago.

Two years into his presidency, Richard Nixon realized the reason his predecessor, Lyndon Johnson, had installed a system to record his meetings and telephone calls. It was because this was the only way to have proof of what was being talked about in the White House, so he reinstalled the recording system that he'd initially wanted removed.All the conversations that happened between 1971 and 1973 in the Oval Room and the Cabinet Room were recorded. There are 3,500 hours of record, including the references to Watergate.But 18.5 minutes from the 200 minutes concerning the scandal were missing. It includes a conversation between Nixon and H. R. Haldeman, three days after the Watergate break in. The President himself said he didn’t recall what was discussed in that moment, so it might be that all the evidence is gone.

Harold Holt was Australia’s 17th Prime Minister from 1966 to 1967. He was not very fond of the idea of having bodyguards, but when a window in his office was shattered by a sniper and the leader of the opposition was almost assassinated, he agreed on having one. But only for when he was working.The Prime Minister was known to be an outdoorsman, and he especially liked the ocean. Others pointed out that his hobby was quite dangerous and his doctor suggested to avoid over-exerting himself, but Harold Holt was not listening to anyone.But it proved to be fatal after all.

During a swim at Cheviot Beach near Portsea, Victoria, the Prime Minister was engulfed by water and just disappeared. Helicopters, watercraft, police divers, and two naval diving teams were searching for his body. Eventually 340 people joined the biggest search in Australian history but no body was found.Most likely Holt overestimated himself as witnesses remember a large swell and visible currents and eddies. However, there are theories that this could have been a suicide or that he faked his own death to be with a lover. We may never know.

You might have heard about the Man In The Iron Mask from fiction literature or movies but they are actually based on real-life events. He was a prisoner who was arrested in 1669 or 1670 and was known for wearing a veil during the whole 34 years he was imprisoned so nobody has seen his face.He actually didn’t wear an iron mask. It was a black velvet cloth, but Voltaire made it more dramatic. He was also the one that proposed the popular theory that the man was the older, illegitimate brother of Louis XIV.The basis for this guess is that the prison where the Man In The Iron Mask was held was used for men who were an embarrassment to the state. Also, no other prisoners hid their faces and this particular one had "two musketeers at his side to kill him if he removed his mask" as King Louis's sister-in-law, Elizabeth Charlotte, wrote in a letter to her aunt.

The Vatican Library has a lot of secrecy surrounding it as it is not open to the general public. The most interesting part of the Library is the Vatican Apostolic Archive. It was separated from the Vatican Library in the 17th century and it contains letters written by the popes, letters received by popes, and all acts promulgated by the Holy See.The oldest document is a loose parchment page from 809 CE. It indicates a donation to a church in Venice. The Archive has the 1521 papal bull of excommunication of Martin Luther and it also holds the letter from Henry VIII asking a divorce from his wife.

The decision to reject the request led the King of England to create his own church where divorce is accepted.What makes the Archives so mysterious is that they have over 1,200 years of historical documents. So infinite numbers of pages in various languages neatly put on shelves that go on for kilometers. But only academic researchers are allowed to enter and that’s a few thousand people in a year, so it is safe to assume that there is so much material that nobody has ever even tried to read.

The genius German physicist Albert Einstein passed away in Princeton Hospital, New Jersey on 18 April 1955. He died because of internal bleeding caused by the rupture of an abdominal aortic aneurysm.Einstein knew he was going to die as he refused treatment because he didn’t believe in prolonging life artificially. And he probably had time to think about what would be the last thing he would like to say.Coincidentally, there was a nurse at the time of Einstein’s death and she actually heard him mutter something, but she didn’t know what exactly it was as she couldn’t understand German. Maybe Einstein revealed an incredibly important realization or he just said goodbye to the world in his native language: the world has to deal with never finding it out.

In 1987 on a Sunday night, people in Chicago were watching the news on WGN-TV when the broadcast was interrupted by a person wearing a Max Headroom mask and sunglasses. The same thing happened with another TV channel, WTTW, that was broadcasting an episode of Doctor Who.The man didn’t say anything comprehensible and when he was done, the screen came back to the news and to the Doctor Who episode. The technicians who were working at that time were trying to take back control, but they couldn’t. They were also unable to trace where the signal was coming from because nobody competent to do that was working that night.For that time, it was a difficult stunt to perform, but nobody claimed responsibility and the investigation didn’t lead anywhere. Who was this man and what message did he want to send? Maybe it was just trolling? It’s no easier to speculate now than it was then.

Sven Olof Joachim Palme was a Swedish politician and statesman who served as Prime Minister of Sweden from 1969 to 1976 and 1982 to 1986 until he was assassinated. He was an easy target as he walked around without a bodyguard. He was walking from a cinema with his wife just as a regular civilian and was attacked by a person with a gun. Palme was fatally shot in the back at close range and his wife was injured but survived.It is hard to believe that the attack was not political, but it is also hard to explain how the killer knew where the Prime Minister was as the visit to the cinema was a spontaneous decision. Police haven’t found any spying devices in his house, or either of the spouses' workplaces.Three years after the murder, a drug user and alcoholic, Christer Pettersson, was arrested and convicted but later released, so the case still remains unsolved.

Sumer is the earliest known civilization that was located in the historical region of southern Mesopotamia (current Iraq). Sumerians were the first to use a written language, they invented a number system, the first wheeled vehicles, sun-dried bricks, and irrigation for farming.But historians are not completely sure where they came from. They had an isolated language, meaning it was not related to other surrounding languages, so that makes it difficult to trace their journey. So they suggest that Sumerians might have come from North Africa, while according to some other data, they might have originated in the Caucasus. There are even more theories and that just shows how mysterious the origins of the people who created the first human civilization are.

Most scientists agree on how our universe started. They think that an extremely hot and dense point just started to expand and is expanding to this day. They call it the Big Bang Theory. But what was before that?We truly don’t know and there could be as many theories as there are people. It could have been something that our minds can’t even grasp. And even if we do find out what the universe was before the Big Bang, then it raises the question what was before that? Where did the thing that came before the Big Bang start? Maybe it’s even better if we don’t know.

Jerry Ehman was volunteering as an astronomer in the Big Ear Radio Observatory as a part of NASA’s project to search the sky for radio signals from intelligent life in space. Part of his work included going through printouts of data.On August 17, 1977 he noticed an unusual sequence of numbers and letters: 6EQUJ5. Jerry Ehman quickly realized that this could have been something huge, so he took a note on the paper expressing his surprise with one word “Wow!” which became the name of the signal.It was a strong signal, but it didn’t reappear and scientists were confused as to the origin of it. Nothing similar has ever been detected to this day and maybe it was just a glitch in the technology or someone actually wanted to contact us from outer space.

The oldest evidence of written language dates back to 6,000 years ago, but what about the spoken language? Surely, it was spoken a lot earlier than that. Scientists estimate that it might have started forming roughly 150,000 years ago, of course, in the most primitive form as the vocal tract which would permit the modern range of speech sounds formed about 100,000 years ago.Scientists believe that there is one proto-language that all other languages formed from and that it was born because of the need of means of communication. But it doesn’t seem that some kind of clear evidence will show up that will definitely answer the question of how languages came to be and evolved.

The Indus script or the Harappan script is what scientists think to be a text made of symbols produced by the Indus Valley Civilization that flourished from about 2600 BC to 1900 BC.The symbols depict human and animal motifs but they haven’t been deciphered. Linguists can’t even agree on what kind of language it is and it doesn’t seem to have connections with other languages that were used in the surrounding areas. There are about 400 symbols, so at least they agree that they don’t represent phonograms and instead syllables.The script could possibly tell us more about the Indus Valley Civilization as we have the least information about it among the biggest ancient civilizations and most probably not being able to read the script is one of the main reasons why.

The Earth contains infinite secrets and humans are not yet able to explain them all. One of them is the Great Unconformity. It's a gap in the rock record between 100 million and 1 billion years long. This phenomenon occurs all around the world in different places with different variations in layers and scientists can’t explain what happened.Rocks look like a cake with layers getting older as you go down. And the change of age is gradual, but when it’s more than 100 million years, it can’t be explained by just simple erosion, though researchers can’t think of anything more logical.