Been reading up on it and watching vids. The internals ramp hypothesis seems reasonable, but then why was it just used on the great pyrmid? I've not heard of any evidence for khafre's Pyramid, for example... An external ramp would have had to have been as large as the pyramid itself. In the middle ages the then Sultan of Egypt tried to dismantle the Red Pyramid but gave up because it was too much hassle. Perhaps the ramp was increased in pitch as the Pyramid grew taller as smaller blocks were used and the ramp used as rubble.