I will never believe that men with primitive tools built the pyramids. The adhesive (NOT CONCRETE) that holds the giant granite blocks in place is so stong that it can tear the stone from an adjacent block when forced apart with modern hydraulic equipment. The stone blocks are not just stacked and fitted one atop another, in the vertical centerline or middle of each side of the pyramid you can see at certain times of the day when the sun shines just at the correct angle that each side is pre-stressed. The shadow cast by the sun clearly shows this, the center or vertical midline is slightly sunken as you look further away from the pyramid corners. Its a marvel of engineering well beyond man's capabilities of the time and to this day engineers would have no clue as how to pre-stress the pyramid perfectly and keep the foundation level to stabilize the massive weight of the structure once the building began, to prevent sinking to one side or another. Even with our modern equipment, it would be a mumental task not really attainable. Just the logistics of setting up the foundation along with sourcing granite from local quarries and then moving these giant stone blocks, some that weigh up to 300 tons to the site would be impossible. Just my two cents. For those interested, The Lost Book of Enki of which the text is from ancient 6000 year old Summerian clay tablets, may shed some light on the subject on who built these structures. These ancient texts detail the account of many mysteries. The book was compiled Dr. Zachariah Sitchin one of a few researchers in the world that could read Assyrian and Summerian texts.