The world is filled with unknown secrets, myths and unanswered mysteries that come to haunt us every time we think of that particular place. Some of these tease us with half-seen answers and a whole host of probable solutions, while the others give us no clue whatsoever. There may be semi-scientific reasons for some others, while the others are rooted in history.
IBTimes UK five of the most famous and unsolved mysteries in history
The Mary Celeste was launched in Nova Scotia in 1860 - more than 50 years before the Titanic tragedy. The Celeste, when it was launched, was fondly nicknamed the "Amazon" - she measured 103ft in length and weighed 280 tonnes; she was listed as a half-brig.
Over the next ten years, the ship weathered several storms and mishaps at sea and also exchanged hands several times. Her last owners bought her from a New York salvage auction, for $3,000 and she was re-christened "Mary Celeste" under the American flag.
Her final voyage was under a Captain Benjamin Briggs, a 37 year old veteran with three previous commands. The ship set sail on 7 November, 1872, departing New York with Captain Briggs, his wife, young daughter and a crew of eight onboard. Loaded with 1700 barrels of raw American alcohol she was headed for Genoa, Italy.
Unexplained disaster struck midway through the voyage and the ship was found floating at sea, in the middle of Strait of Gibraltar, with no clue of what happened to the captain, his family or his crew. There were no signs of struggle on board and all the ship's documents, with the exception of the captain's log, werew missing.
A year later two lifeboats, with one carrying a body and an American flag and the other containing five bodies, were reported in Spain. It has been alleged that these floating bodies could be the remains of the crew of the Mary Celeste. The bodies were apparently never identified.
The Bermuda Triangle is the expanse of water between Florida, San Juan and Bermuda, whose connecting co-ordinates forms the infamous zone of mystery. There have been reports of innumerable planes and boats going missing in this region, all under mysterious circumstances. This zone is known to be one of the world's most heavily traversed shipping lanes, with vessels commuting daily to ports in the Americas, Europe and the Caribbean Islands.
Various reasons have been volunteered for the disappearances, including bad weather, alien abductions, time warps and even talk of the suspension of the laws of physics. The first unexplained event occurred in the 1950s when the story of Flight 19 - a group of five US Navy bombers on a training mission - was made public.
"We are entering white water, nothing seems right. We don't know where we are, the water is green, no white," the flight leader reportedly said via radio. It was also claimed that Navy officials said the planes "flew off to Mars".
Sceptics believe that such incidents have been greatly exaggerated and that ships have sunk at many places around the world; the Bermuda Triangle is no exception.
There are, of course, a host of other theories, including those that suggest the Earth's magnetic field played its part in confusing instruments - apparently a magnetic compass loses all its bearing in this zone. The other most commonly cited reason is the tidal waves - influenced by the magnetic disturbances previously alluded to.
It is worth noting that whatever reason is most in vogue at any given time, there is still no hard evidence as to what happened to the many missing planes and boats.
The Mayan 2012 Doom's Day Prophecy
According to the Doom's Day Prophecy, the world is expected to end on 21 December, 2012.
Theories speculating the end of the world have long been a part of several ancient (and even modern cultures) and range from religious warnings to those based on astrological calculations. Some say the Sun will soon die out and as a result all life on Earth will follow suit, while others believe the Earth will one day by covered by gigantic tidal waves. Essentially, theories about Armageddon are always a good crowd-puller.
However, the most popular of all these theories must surely be the prophecies attributed to the Mayan civilisation.
The theory is based on the idea that when the ancient Mayans plotted our position in the Milky Way, they created a special astrological calendar and, on the Winter Solstice (in the Northern hemisphere) in 2012, the Earth will pass into a new astrological phase and something dramatic could happen - the world ends.
Unfortunately for people who believe in this theory, there is little solid evidence to support the idea that the alignment of planets in relation to distant star constellations viewed from our Earthly perspective could have so drastic an effect on life here.
Mayan scholars are of a similar opinion and reject the idea of a doomsday prophecy. They believe the Mayan calendar, like all calendars, was made to keep track of time. Their most basic solution - the Mayan year may end on 21 December, much like ours does on 31 December. The new astrological phase may be nothing more than a New Year.
UFOs and Area 51
The first Unidentified Flying Object (UFO) was reportedly sighted in 1878, in Texas, when a farmer said he saw a large, dark and circular flying object moving at great speed. Another famous early sighting was in the UK in 1916, when a pilot reported seeing a row of lights that rose and disappeared into the sky.
After the idea of of UFOs gained popularity, thanks to science fiction, in the 1950s, the number of sightings, predictably, went through the roof. There are several theories explaining various aspects of paranormal phenomena (or at least those belived to be paranormal) ranging from the traditional Extraterrestrial Hypothesis (aliens visiting us from another planet) to the Inter-Dimensional Hypothesis (aliens popping over from a parallel universe).
Although there are indications that extraterrestrial life forms may exist somewhere else in the universe, there is hardly any to suggest aliens are visiting us in flying saucers or making crop circles. A large part of the sightings attributed to UFOs can reasonably be attributed to natural phenomena like weather changes or astronomical events like comets and meteors or man-made objects like airplanes, helicopters and weather balloons. In addition, most offered photographic and video proof of aliens can be dimissed either as hoaxes or, simply, dust on the camera lens. Meanwhile, night-time alien visitations can be explained by the hallucinogenic effect of the sleep disorder Sleep Paralysis.
UFO conspiracy theories, nevertheless, abound.
One of the most famous, undoubtedly, is that which surrounds Area 51 in Las Vegas, Nevada. This is reportedly a large US Air Force base that not only conducts secret "black budget" experiments and tests similar aircraft but also has a hand in other, let's just say secret, experiments.
The Pyramids of Egypt
Like most unexplained mysteries, the pyramids of Giza in Egypt are really something special. Designated as one of the greatest wonders of the ancient world, we still do not know how the Egyptians actually built these wonderful structures, least of all the gigantic Great Pyramid of Cheops (Khufu), some 5,000 years ago.
The Great Pyramid is the size of a 40-floor building and engulfs and area large enough to fit 10 football fields. More than 2 million stone blocks were used to make the pyramid, each weighing between two and five tonnes; these were cut from a distant limestone quarry on the other side of the Nile and according to experts it maybe took some 400,000 men 20 years to complete.
The engineering wonder of the structure aside, there are some unexplained mysteries.
In the 1940s, a French hardware dealer reportedly spotted some mummified animals exactly one-third up the height of the pyramid. The remarkable thing was they showed no signs of decomposition. He deduced that the pyramid shape was responsible for preserving these creatures.
Later, a Czech radio engineer conducted a series of experiments in which he placed a brand new razor blade inside a 1:1,000 scale model of the Cheops pyramid. He aligned his pyramid on a north-south axis exactly like the one. After using the razor 50 times, he was forced to conclude it was only getting sharper from its time inside the pyramid! It took him 10 years to obtain a patent for this idea, which he claims still has no scientific explanation today.