In the Russian Ural Mountains in 1959, a group of seasoned hikers perished under unexplained circumstances. Their tent was discovered torn open from the inside, and their traumatised bodies were found dispersed over the countryside.
At least five women were killed by Jack the Ripper, an unidentified serial killer who terrorised the streets of London in 1888. The murderer was never found, and the case is still one of history's most well-known unsolved mysteries.
The year 2014 saw the disappearance of Malaysia Airlines Flight MH370, which had 239 passengers on board and was travelling from Kuala Lumpur to Beijing. The plane has never been located despite intensive search attempts.
The dismembered body of Elizabeth Short, often known as the Black Dahlia, was discovered in 1947 in Los Angeles. Despite several suspects and hypotheses throughout the years, the case is still unresolved.
A 15th-century manuscript written in an unknown language and filled with mysterious illustrations has puzzled researchers for centuries. Its purpose and meaning remain a mystery.
A piece of paper that read "Tamam Shud" was found in the pocket of an unnamed guy who was discovered dead on an Australian beach in 1948. (meaning "ended" or "finished" in Persian). The name of the individual and the reason for his death is still unclear despite thorough inquiries.
It's been 26 years and there is still clue about the Phoenix Lights, when countless people noticed a cluster of odd lights over Phoenix, Arizona, in 1997, and the phenomena were reported by countless more. Even now, there is no explanation for the lights.
In 1987, a television broadcast was hijacked by an unknown person dressed as Max Headroom, a character from a TV show. The incident still remains unsolved.
There was a mysterious radio transmission from space that was picked up in 1977. It is referred to as the Wow! signal and is still one of astronomy's greatest mysteries.
On their farm in Bavaria, Germany, a family of six was brutally killed in 1922. The murderer was never caught, and the case is still unresolved despite multiple investigations and suspects.