It is not known when the ravens first came to the Tower of London but their presence is protected by legend. Traditionally, with birds of ill omen, it is their absence rather than their presence that is feared at the Tower of London. There is debate as to when the legend dates from, but the legend say that if the ravens leave, the Tower would fall and the Kingdom would fall, so Charles II decreed that there must always be at least six here at the Tower of London