Here is something I came across reading The Golden Thread of Time – passages hewn into the Giza plateau 87 metres East of the Great Pyramid.
Flinders Petrie commented upon them, finding them to be similar to the configuration of the internal passages inside the pyramid. He also thought they were created before work began building the Great Pyramid had begun, as though they were a mock up for the layout of the internal passages. They became referred to as trial passages. But to build trial passages would seem a bit strange, although what isn’t strange about the pyramids and the plateau! So much has been said of the need for secrecy with regard to the building of the pyramids so they would not be looted. Such secrecy, if required because it was a tomb containing valuables, (nothing convinces me yet that it was actually used or built as a tomb) then marking out the interior in plain site would be ridiculous.
Crichton Miller, in his book, quotes published work by Mark Foster wherein it is seen that the essential emphasis of these passages is the juncture where the ascending and descending passage meet and, to him, indicates a vertical passage at this point that is yet to be uncovered within the Great Pyramid. Such a vertical shaft could lead to a further system of passages and perhaps an undiscovered chamber, as with the small 8″ square tunnels that lead from both the ‘Kings’ chamber and ‘Queen’s’ chamber, the latter having been hidden behind a wall just 8″ thick and which doesn’t exit the pyramid either. Miller points out that when Rudolf Gantenbrink’s robot explored the southern shaft in the ‘Queen’s’ chamber it showed that just before the ‘door’, or portcullis slab, it is lined with fine Turah Limestone, the material used solely for the chambers and casing of the pyramid. This then may indicate that there is something of significance beyond the slab, possibly a space, or chamber, which is met by the as yet uncovered vertical shaft. I’m not so sure, but the idea is well suggested. A reason for such a vertical tunnel would need to be explained, but then there remains conjecture as the the purpose and course of the already known tunnels.
Many have speculated and made suggestion that other tunnels, chambers and passages may yet lay unexplored within the Great Pyramid. Foster cites Gantenbrink’s observations and comments, in effect stating that he sees detailed evidence from his findings in the shaft to support the idea that a further chamber exists within the vicinity. With so little contemporary, high tech, safe and non-destructive investigative work taking place within the pyramid, I suppose all such things are yet possible to discover.