...However Dr Dobrev noticed that the causeway connecting Khafre's pyramid to the temples was built around the Sphinx - meaning it was already in existence.
Let me see if I have this straight... The Sphynx was built by Khafre's half brother (and Khufu's son), Djedefre, who followed him as Pharoah... and this Frenchman with the Russian name deduced all this because Khafre's causeway from his Pyramid JOGGED to avoid the already existing Sphynx???? Did Djedefre build it BEFORE he became Pharoah...
NOSE PICKING! He reached in and found a bugger and now is explaining the whichness of the why because of what he found on the tip of his finger!
Djedefre preceded Khafre on the throne. His burial complex at Abu Roash north of Giza was left unfinished, presumably because of his short reign, and was picked apart for building stone over the centuries. Djedefre's brother didn't bother to finish it either, making it plausible that there was an intrafamily struggle of some kind. Menkaure, son and successor of Khafre, wasn't able to build nearly as big a pyramid at Giza, and his successor reverted to a mastaba, constructed some miles south. It's also plausible to suggest that Egypt was coming apart, either due to the squabbles and dynastic struggles, or due to the weather, or due to a massive migration into the Nile Valley by other ethnic groups, or some combination of these.