I'm always amazed to think the Egyptians were building Pyramids and temples on that scale at the same time as we British were standing a few stones up and calling it Stonehenge.
I agree there's nothing shabby about Stonehenge. It's very impressive. I've stood next to both and they both take my breath away, but Stonehenge is surely not in the same league as a Pyramid.
There must have been climate change on a massive scale since the days those were built.^ While it's a desert not there would have been lush vegetation to enable a society to thrive and build those.
For Sandy: http://www.touregypt.net/images/touregypt/pyramidreligion1.jpg
Until the Nile was dammed at Aswan in the 1960s, the annual floods reached the bit where the Sphinx is - the mortuary temples of the Pyramids at Giza. The canny ancient folk built the grand tombs of the dead beyond the lush well-watered land of the valley bottom. You climb up the incline on the west side of the river to reach the pyramids and other tombs. No major climate difference between then and now.