For centuries, half a dozen ravens – dubbed the "Guardians of the Tower" – have lived a cozy life in the Tower of London. In the 17th century, King Charles II decreed that if the ravens ever left the tower, the structure would crumble, and the entire British Empire would collapse.
Many consider it an odd choice, since ravens and similar species of black birds are often more closely associated with bad luck than with good. Regardless, since that day, the ravens have remained welcome guests in the tower, charged with keeping the once mighty empire in good stead. In modern practice, the birds' wings are clipped to encourage them to stay put, and a few extra ravens are always on hand to make sure the group never numbers fewer than six.
This foresight may have saved the nation in 2013, when a sneaky fox managed to enter the tower and feast on a pair of unlucky ravens named Jubilee and Grip. The British take this superstition – and the threat of wily foxes – so seriously that a team of four cares for the birds round-the-clock, ensuring they live a pampered life [source: BBC]. What bird could ask for more?