How did the ancient Egyptians build the pyramids and what gave them the idea to build them?

Shortly after coming to the throne the Pharaoh Khufu commanded Hemiunu, his overseer of public works and chief architect to prepare a burial place in keeping with his status as a god-king a launching for his soul to join his ancestors amongst the stars.
The royal survey team set to work marking out the site. Great care was taken in orientating the site to the four points of the compass and in levelling the site to provide a foundation for the pyramid. When the slaves had cleared away the sand and rubble highly skilled masons were called in to level the foundations. This was done by cutting a grid of channels and filling them with water. The rock was then cut back to the water level to make it perfectly flat. Finally the water was drained away and the channels filled with rubble.
At any one time as many as 20,000 workers may have been involved. Some of them were free men doing particular tasks such as masons, tool makers, carpenters, scribes and supervisors. Many of course were slaves, naked slaves too low in status to wear clothes.
Throughout the Pharaoh's reign, the construction site teemed with workers of all kinds, toiling in the hot sun to complete the monument before the king's death. Day after day, year after year, the quarries rang with the sound of hammer and chisel on stone. Through the dust the bodies of the naked quarry slaves stand out dark against the yellow limestone. After they had cut deep enough to define a block, they packed the riven rock with pieces of porous wood. Water is poured on the wood. It expands so fast that the block splits out with a crack. After the stone blocks are extracted from the quarry face they are lowered onto sledges. A mark is made on the stone by a scribe. This aided them to place the blocks in the pyramid just as they came out of the quarry ensuring a good fit without further finishing.
From dawn to dusk gangs of slaves drag the sledges loaded with stones each weighing about two tons to staging areas at the base of the pyramid. Most of the stone blocks proceed up the ramp without future handling. Only a fraction of the stone blocks needed to be cut to precise dimensions by the masons. The slaves begin hauling the loaded sledges slowly up the clay and rubble ramp. The noise on the ramp was one of chanting slaves, the rumble of heavy sledges and the swish of the overseer's lash.
At the working level teams of slaves called setters shifted the blocks from the sledges into their designated positions. These men use a combination of levers, brute force and experience gained from years of hard labour. Once the stones had been delivered the hauling gang would make their way down the ramp carrying their sledge, in order to make the same back breaking journey up as they would several times a day.
Other slaves are employed in maintaining and extending the ramps as the pyramid grew. These ramps are made of rubble, bound together with desert tafla (a type of clay) and laid with planks to ease the passage of the ramps. Rows of slave labourers are seen breaking up waste material from the quarries, mixing them with the desert tafla clay and loading the finished mixture into baskets. Individual baskets are loaded onto the shoulders of slaves for delivery to the ramp builders on the pyramid.
Boats made from reeds deliver brilliant white limestone from Tura just across the river. Here the slaves, in light provided by primitive lamps, toil in manmade caves to obtain the best stone. This stone will be used for the outer case of the pyramid. Once put in place and polished the effect will be dazzling.
Granite came from Aswan located in the far south. Granite was used for the lining of the burial chamber and the internal passage leading to it or in some instances the lower courses of the pyramid. These blocks were the largest in size used on the structure, for example, some of the granite stones used on the Great Pyramid at Giza weighs up to 70 tons. Copper chisels used for quarrying limestone could not be used, a harder material was required. Balls of dolerite, a hard, black igneous rock, are used in the quarries of Aswan to extract the hard granite. This is a place of great heat, dust and noise a hellish place to be sent to work. The dolerite "pounders" were used to pulverize the stone around the edge of the granite block that needed to be extracted. Teams of slaves, their naked bodies gleaming in the hot sun, pound away for weeks in order to expose enough stone for the block to be extracted from the quarry. At the bottom, they ram wooden pegs into slots they have cut, and fill the slots with water. The pegs will expand and split the rock with a resounding crack much more impressive than anything heard with the softer limestone. With much cursing and labour the slaves lower the great blocks onto sledges. As many as two hundred slaves straining on ropes drag the loaded sledges along a causeway to the river where they are loaded onto barges and floated downriver with the current to the pyramid site.