The click

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On January 2, 1999, Henri Houdin, an A&M engineer, watched Jean-Claude Delassus's documentary "Le Mystère des Pyramides" on television; at the end of the film, he had this "click": "If I had to build a pyramid, I'd build it from the inside".
On January 4, he made the first drawings imagining an internal spiral ramp to transport the limestone blocks. The "internal ramp" theory was born. He then asked his son Jean-Pierre, architect DPLG, to model his idea in 3D. The adventure began and lasted for over 25 years, taking on proportions unimaginable at the time. The first article on the theory was published in the CNISF (Conseil National des Ingénieurs et Scientifiques de France) magazine ID in October 1999.