Credit : http://en.wikipedia.org/wiki/Tower_of_London
I heard this story long time ago and I was very interesting in it. as we know this place is a prison and execution in the past. The interesting of this place is ravens which live at the tower. The number of ravens in the tower is the most important things to attend.
The number of ravens which live at the tower are always six. If the number of ravens decrease there will be something happen (for sure not a good thing) and if all the ravens die, it means the end of British Royal Family too.
This story was written in the report by the times of King Charles II about 17th century. This is very serious and delicate. All the knights and servants must report if something wrong happen with the ravens. But if some of ravens die it must be replace by a new one immediately.
All the ravens have their names and the burial of the ravens are officially too. But if all the ravens die simultaneously at the morning of the next day (for example Bird flu). All of the British Royal Family members will be vanished too.
I think when the World War 3 happen someday. The first thing to attend for the British Royal Family is how can they protect their ravens at that time.