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
The Platypus used to be considered a myth like Bigfoot and the Yeti.
18
There's a mysterious dwarf planet between Mars and Jupiter called 'Ceres' which has never been visited by spacecraft or photographed in detail, however, Earth-bound telescopes reveal a large bright shining spot on the surface of this planet, the origin and nature of which are unknown.
5
There is an island near Italy that was the site of wars, a dumping ground for plague victims, and an insane asylum. It's considered so dangerously haunted that the Italian government does not allow public access.
78
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