There is a mysterious and loud radio signal known as 'the space roar' that has yet to be explained.
15
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
There are pictures of Knights fighting Snails in old Medieval manuscripts - and nobody knows why.
23
Scientists lit a cave of natural gas on fire in 1971 expecting it to only burn for a few days; it still burns to this day. It has been nicknamed "The Door to Hell".
19