KV5 is the tomb of the sons of Ramses II, and the recent discovery of its great extent is perhaps the most amazing discovery in the Valley of the Kings since the discovery of the tomb of Tutankhamun.
Being near the entrance to the Valley, over the centuries it had suffered the fate of other low-lying tombs, which was to be filled with rubble washed down in the flash floods that accompany thunderstorms over the valley. In addition, it had been robbed in antiquity.
The tomb was examined several times once exploration of the Valley in relatively modern times started, first in 1825 (by James Burton), and later in 1902 (by Howard Carter, discoverer of the tomb of Tutankhamun). However, they were not able to penetrate past the first few rooms, and thus saw nothing unusual about the tomb.
It was not until the Theban Mapping Project, under Kent Weeks, decided to clear the tomb (in part to see it it would be damaged by proposed building works nearby, and in part so that it could be mapped) that the stage was set for the discovery of its true nature. During the initial stages of their work, from 1987 to 1994, the team was unaware of the true scope of the tomb.
It was only in 1995, after doing substantial clearing in the outer chambers of the tomb, that they were stunned to discover the long corridors, lined with rooms (approximately seventy in all), running back into the hillside; a discovery which amazed the world and re-ignited popular interest in Egyptology.
Further excavations have revealed that the tomb is even larger than that, as it contains more corridors, with more rooms, running off from other parts of the tomb. Over one hundred and twenty rooms are now known, and work is still continuing on clearing the tomb.