The exact cause of death and burial site of Genghis Khan is unknown, because all of the 2000 funeral guests and 800 soldiers were killed in order to preserve the secret.
16
There is a mysterious and loud radio signal known as 'the space roar' that has yet to be explained.
15
In 1968, a car driven by bank employees was pulled over by a motorcycle cop claiming the car had been rigged with a bomb. The cop got under the car to “defuse” the device. When the car started to smoke, everybody ran. Then the “cop” just drove the car away. The 300,000,000 Yen robbery remains unsolved to this day.
20
There are pictures of Knights fighting Snails in old Medieval manuscripts - and nobody knows why.
23
In 1518, a "dancing plague" struck Strasbourg, Alsace, whereby hundreds of people danced fervently in the streets over the period of a month. Some suffered heart attacks or strokes, and many others died from sheer exhaustion. It remains unexplained.
19