Here then, we have clear evidence that a movable entrance stone was fitted to the Great pyramid, and that the descending passage had been visited, perhaps many times, throughout recorded history. To gain entry to the pyramid, however, was still not easy. Unless there was a flight of steps cut into the now-missing casing blocks, a series of ladders would have to be erected against the side of the pyramid to reach the door.
There is also the problem of why Ma'mun was tunnelling inside the pyramid in the first place. Not only was the presence of the true entrance to the pyramid well known in classical times but people were also aware of the descending passage and the subterranean cavern at the very bottom of the pyramid. Strabo says of the original entrance to the Great pyramid: "The Great Pyramid, a little way up on one side, has a stone that may be taken out, which being raised up there is a sloping passage to the foundations."
The classical account of the discovery of the upper chambers inside the Great Pyramid at Giza is well known. In the ninth century an Arab governor of Cairo, known as the Caliph al Ma’mun, decided to see for himself what lay inside the Great Pyramid. Because the entrance to the pyramid was concealed and its location unknown, his workers began to excavate a tunnel boldly through the casing and core blocks, with hammers and chisels.
The next question we have to ask is, where on the surface of the Earth does this large pyramidal triangle lie? As is explained in K2, Quest of the Gods, if we use Giza as our longitudinal zero meridian, then the great triangle lies across the western Himalaya, in a region known as the Karakoram.