Godric Gryffindor, Helga Hufflepuff, Rowena Ravenclaw and Salazar Slytherin are to this day renowned as four of the great wizards and witches of all time, having created the first and finest school of witchcraft and wizardry in the world, Hogwarts. What many don't know is that all four friends each left a secret inside the castle. A secret that they kept, even from each other.