You have to climb and follow paths that don't always appear on maps in order to discover one of the best-kept secrets of the dynasties of pharaohs which was long hidden in the sand. Here, Egyptologists believe there was a perfect pyramid which served as a tomb for the pharaoh Djedefre - a pyramid which hides in its midst a room of almost 20 metres deep and an immense passage that leads deep into the pyramid's heart.

• Zahi Hawass