The pyramid is thought to have been built as a tomb for the pharaoh Khufu, and is the last of the seven wonders of the ancient world still standing. It contains three main chambers: the Queen's Chamber, the Grand Gallery and the King's Chamber, which has two air shafts connecting it with the outside world. Strangely, though, there are two tunnels, about 20 centimetres by 20 centimetres, that extend from the north and south walls of the Queen's Chamber and stop at stone doors before they reach the outside of the pyramid (see diagram).
The function of these tunnels and doors is unknown, but some believe that one or both could lead to a secret chamber. Zahi Hawass, Egypt's Minister of State for Antiquities Affairs, describes the doors as the last great mystery of the pyramid.
Several attempts have been made to explore the tunnels using robots. In 1993, a robot crawled some 63 metres up the tunnel in the south wall and discovered what appeared to be a small stone door set with metal pins. Metal is not part of any other known structure in the pyramid, and the discovery ignited speculation that the pins were door handles, keys or even parts of a power supply constructed by aliens.
Then in 2002 another robot drilled through the stone block and filmed a small chamber backed by a large blocking stone, but little else. Now a robot designed by engineer Rob Richardson from the University of Leeds, UK, and colleagues, and named Djedi after the magician that Khufu consulted when he planned his tomb, has crawled up the tunnel carrying a bendy "micro snake" camera that can see around corners. Read More