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
In 1987, a Chicago TV station had its broadcast interrupted by a pirate signal that shows a man in a Max Headroom mask mumbling and being spanked with a fly swatter. Despite investigations by the FCC and FBI, this became the only known incident in which a hacker interrupted a major TV broadcast without getting caught.
19
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
Since 1982, a radio frequency emanating from Russia has been broadcasting a buzzer-like sound and, periodically, an unknown voice reads orders, names, and numbers. No one knows where exactly it is coming from or what it means.
13
There are pictures of Knights fighting Snails in old Medieval manuscripts - and nobody knows why.
23
A waterfall known as The Devil's Kettle empties water into a hole and nobody knows where it ends up!
18