While browsing through YouTube, I came upon this fascinating documentary in which Andrew Collins and colleagues explain their discovery of chambers and passages under the Giza plateau. As the documentary explains, Collins and his associates developed a belief that the Giza pyramids were laid out to match the Cygnus or 'Swan' constellation. They therefore concluded that the place matching the star Deneb, the main star of Cygnus, should be of great significance. They followed up on their idea, along with well-researched information they gathered together, and found an entrance leading to multiple underground chambers and passageways.
The progress of the researchers has a familiar ring. As has often been the case when enthusiasts have tried to discover the secrets of the Giza site, one person has almost always obstructed their efforts. Zahi Hawass, the head of Egyptian Antiquities in Cairo at that time, first stated categorically that there were no underground chambers at the Giza site, even though the researchers had found and photographed underground chambers. He then barred the entrance to the temple concerned. He followed that up by taking a film crew down those same passages but made no effort to explore further. This tactic of Hawass's, of rubbishing theories and then blocking access to the site so that no one can explore further, has occurred multiple times. For example, after Jean-Pierre Houdin developed a sound theory of an inner ramp within the Great Pyramid, he went to Giza and discovered a collapsed corner of the pyramid wall, high up, exactly where an inner ramp could have weakened the pyramid's outer shell. Houdin had a quick look and then rapidly found the site barred to any access. Since that time, no one has been allowed to explore that collapsed corner. Similar events may happen again. Hawass is currently not the head of Egyptian Antiquities, possibly having been sacked (again), but it is possible he may be reinstated, which has also happened before.
I haven't posted a lot of information about new development at Giza in the last few years. Some readers might find this strange, as I did a lot of research on Egypt and I developed an explanation for why and when the Great Pyramid at Giza was constructed. To put it succinctly, the Great Pyramid was built between 3000 BC and 2800 BC in order to take advantage of an extremely rare celestial event; the passage of a star almost directly over the celestial North Pole. This transit occurred in 2787 BC and the star concerned was Thuban, or Alpha Draconis, 'Thuban' is Arabic for the snake and although the star is not the brightest star in the Draconis (or Dragon) constellation, it was designated a long time ago as the constellation's most important star.
The discovery of this solution has been a very strange experience for me. After developing this answer to the mystery of the Great Pyramid's construction and writing about it, I did assume that the answer, based entirely on straightforward astronomy and the Great Pyramid's physical attributes, would be rapidly disseminated, accepted and repeated by others. The solution can't be dismissed as an interpretation as there is no interpretation involved. No translations or hypotheses are required; it's a simple case of geometry and astronomical observation. And yet, I've seen no indication that anyone has picked up this ball and run with it. What's more, my attempts to directly pass on the information to others - researchers, magazines - has met with stony silence; It's all very odd. Understandably, I think, such a complete void of encouragement and interest has sapped my enthusiasm and I've focussed my energies on other topics instead.
I'll keep plugging away whenever possible. In the meantime, do enjoy the above documentary.