London Stone, mentioned by Shakespeare, Blake, and Dickens, is a mysterious, neglected limestone block in the middle of London.
It was recently rescued from a building due to be demolished - and a good thing too, since legends said that the fortune of the city is tied to the survival of the stone!
This relates to the myth that the stone was part of an altar built by Brutus the Trojan, the legendary founder of London. This might be unlikely, but then again no one really knows its origin.
"So long as the stone of Brutus is safe, so long shall London flourish," says the proverb.
Link (via Fortean Times)