In 1547, Holy Roman Emperor Charles V penned a letter to his ambassador, Jean de Saint-Mauris, part of which was written in the ruler's secret code. Nearly five centuries later, researchers have ...

If you are a Sudoku ace or a cryptic crossword champ, you might feel like there is no puzzle you couldn't crack. But there are some hidden messages which have baffled even the brainiest code breakers.

Chelsea's Millie Bright and Aggie Beever-Jones take part in a Chelsea themed quiz in order to crack the secret code.