Top 10 Facts - Unsolved Mysteries [Part 2]

All across Europe, these narrow underground tunnels called Erdstall has been discovered. In Bavaria in Germany alone, over 700 has been found so far. The tunnels are tiny.

Between 1-1. 5 meters high and up to 1 meters wide. The thing is no one knows who build them, for what purpose, or even when they where built.

Some believe that they served some sort of religious or spiritual purpose, while some think the tunnels where simply used for hiding and shelter. But there is not a single written record of the construction of one of these tunnels. They where all seemingly built in secrecy which is strange given that entrances have been found inside houses, near churches and cemeteries, as well as in the middle of the woods.

If the tunnels were used and possibly built by Christians, why do records of Christian kingdoms fail to mention them? It's also very unlikely that they where used as dwellings or any sort of long term inhabitation as there's essentially no archaeological material to be found within them. No residue of any kind except a few minor bits of coal and ceramics dating back from anywhere between the 10th and 12th century.

Beyond that, these tunnels are a mystery. Between 1982 and 1985, a group called The Brabant Killers carried out a number of violent attacks in and around the province of Brabant in Belgium. The killers would usually attack supermarkets and restaurants and randomly killed and tortured 28 people in the process.

According to the few surviving victims, the group consisted of three main leaders called The Giant, The Killer, and The Old Man. What remains a mystery is the motive behind the attacks. They would only steal minor amounts of money and sometimes even throw the money away when they where done.

What makes it even more strange is that after an attack in December of 1983, they just vanished. Almost two years later they would resurface and commit three of their most violent attacks yet and kill another 16 people, before disappearing again. Since 1985, no more attacks have been reported and no solid evidence as to who or why they did it has been found.

Something strange is happening to residents in a village in Kazakhstan. It's referred to as Sleepy Hollow or simply The Sleeping Sickness. At random points throughout the day, without reason or warning, they will fall asleep.

Everyday, the villagers simply fall asleep in broad daylight and won't wake up until several hours or even days later. It's believed to be some form of brain decease but medical experts can't find a verifiable cause for it, much less a cure or some form of prevention method. Other culprits could be radiation or carbon monoxide poisoning, both of which has been disproven.

Welcome to the tiny village of Yangsi in China. This village only has a population of around 80 people, half of which are dwarfs. It's simply been dubbed The Dwarf Village.

What's strange about this is that the probability of stunted growth is about 1 in 20,000. In other words, there has to be a very specific reason for this phenomenon. Some think it has something to do with the soil in the region and the locals believe the village to be cursed.

But as Chinese authorities won't allow outsiders to visit, all we have to go on are a few photographs and speculation. It's the 12th of June, 2009. A man arrives in Sligo, Ireland and checks in at the local hotel.

He writes down the name Peter Bergmann and an address in Austria. 3 days later, he would be found dead at beach not far from the hotel. The information he gave was later found out to be false.

The address in Austria didn't exist and no one by the name of Peter Bergmann could be found to fit his description. His last few days, was captured on cameras in and around the hotel. He can be seen leaving with a purple bag several times only to return without it.

Most likely to dispose of possessions that could potentially reveal his true identity. Examination after his death revealed that he had severe prostate cancer but that he had not taken any painkillers or received any sort of treatment for it. It's believed he committed suicide by drowning.

But what makes the case so mysterious are the lengths he went too to keep his identity hidden. He knew exactly where to go to hide from the cameras and even cut off the labels on his clothes. Before his death he managed to mail a few letters that police where unable to track down.

So someone out there likely knows who Peter Bergmann really was. This photo was taken in 1918. It's a photo of a squadron which served in WWI.

The story goes that three days prior to the photo being taken, a mechanic named Freddy Jackson was killed by an airplane propeller. His funeral had supposedly taken place on the day the photograph was taken. Now here's the thing.

If we zoom in on the top row here, just behind the 4th person to the left, there appears to be someone else in the photo. Members of the squadron later recognized the face as Freddy Jackson. So is this a ghost captured on camera?

Well maybe. It sure looks like it. However a more realistic explanation is that the photo is a composite.

It's essentially where you merge two or more photos together before presenting the final image. A technology that definitely existed at the time and was often used to include deceased family members in family photos. Another discrepancy is the fact that the story of Freddy Jackson doesn't appear to be true.

There was a man named Frederick William Jackson who died a few weeks before the photo was taken. However he died of heart failure and was a marine artilleryman, not a mechanic. Now something more recent, in late 2014 just outside of Stockholm, Sweden something strange happened.

On October 17, the Swedish military received reports of a damaged submarine in the Stockholm archipelago. After numerous days of searching and intelligence gathering, they had conclusive evidence that a foreign submarine had secretly reached far into Swedish waters. And I mean, they got really close.

It would be the equivalent of finding a submarine lurking around in Lower Bay just outside of New York or far into the Thames River in London. It just shouldn't happen. But it did.

The military believes the submarine to be Russian as encrypted transmissions sent over emergency frequencies known to be used by Russian units was recorded. The sources of these transmissions were identified as a submarine and a military site in the Kaliningrad region. But there's no definitive proof and Russian officials has denied the accusations.

But no matter who it was, the question is, why? What intentions could they've possibly had? We may never know.

On a remote island in the southeastern Pacific Ocean hundreds of absolutely massive statues can be found called Moai. At some point during the first millennium, people settled here on Easter Island and created a thriving culture which would become known as the Rapa Nui people. In 1722, the island became known to the outside world and ever since, people all over the globe has been trying to figure out how exactly they did it.

How did they erect these gigantic monoliths that could weigh up to 86 tons. Not only that, they somehow transported hundreds of them to various location across the island. And it should also be noted that the island was almost completely treeless when they did all this.

The most obvious theory is of course that they simply dragged the statues on the ground using ropes, but that would take an enormous amount of manpower, time, and effort. Keep in mind there's a total of 887 of these things. Another theory is that once erected, they made the statues sort of walk by attaching ropes to the top and then wiggle it side to side.

This theory was actually tested using a 5 ton replica and it actually worked. The question is, would it also work when the statue is 10 meters high weighing over 80 tons? In 2004 a man, who would later adopt the name Benjamin Kyle, woke up outside a Burger King in the US without any clothes, any ID, or any memories.

He was soon diagnosed with psychogenic amnesia as he could not remember who he was or even his own name. Today he is the only American citizen officially listed as missing despite his whereabouts being known. Even with the widespread media coverage of his bizarre case, no one has ever come forward claiming to have known Benjamin Kyle in his past life.

One unfortunate side effect of not having your own identity is that, without a social security number, he's unable to do normal things such as having a stable job. It really is a mystery how absolutely no one has recognized him. Every now and then, discoveries are made that forces us to question the things we taught we knew.

Evidence so far has suggested that 13,000 years ago, humanity consisted of simple minded hunters and gatherers. People who lacked the ability to create complex symbolic systems, social hierarchies, and division of labour. Yet here, at Göbekli Tepe in Turkey we have found evidence that speak against all that.

This over 13,000 year old complex is believed to have served as a sanctuary making it the oldest temple and religious site in the world. The temple not only predate the invention of writing and the wheel, they were built before the so-called Neolithic Revolution when humans went from hunting and gathering to developing agriculture, settlements, and the domestication of plants and animals. And the existence of this place raises far more questions than it answers.

How did nomadic, neolithic man manage to organize a workforce to build this complex? Why was it built? Why does it predate similar structures by thousands of years?

What caused them to become so much more advanced then other communities of that time? This discovery could force us to rethink a crucial part of human evolution. For now it will remain an unsolved mystery.