well it is very far fetched that they did it all on their own with such simple methods because the archeologist went on and on about pottery etc but never mentioned remains of ramps cranes or anything else so what did they do go out there with picks and shovels ?, where did the rock come from eh ? did they transport it for thousands of miles from where ? we don't even know where the stone came from, an extraterestial civilization leaving could easily take away al evidence of its being there e say there is evidence of the egyptian because they left stuff around but some one wanting to remove their evidence could have done so