The derivation of the word "pyramid" is obscure. Per-em-us, an ancient Egyptian term meaning "straight up", seems likelier than the Greek pyramis - "wheaten cake", a facetious descriptive term for these novel monuments. Then again, "obelisk" comes from obeliskos, the ancient Greek for "skewer" or "little spit".

 

Whatever, the Pyramids' sheer antiquity is staggering. When the Greek chronicler Herodotus visited them in 450 BC, as many centuries separated his lifetime from their creation as divide our own time from that of Herodotus, who regarded them as ancient even then. For the Pyramid Age was only an episode in three millennia of pharaonic civilization, reaching its zenith within two hundred years and followed by an inexorable decline, so that later dynasties regarded the works of their ancestors with awe. Fourteen centuries after the royal tombs of the Old Kingdom were first violated by robbers, the Saïte (XXVI) Dynasty collected what remained, replaced missing bodies with surrogates, and reburied their forebears with archaic rituals they no longer comprehended.

The Pyramid Age began at Saqqara in the 27th century BC, when the III Dynasty royal architect Imhotep enlarged a mastaba tomb to create the first step pyramid . As techniques evolved, an attempt was made to convert another step pyramid at Maidum into a true pyramid by encasing its sides in a smooth shell, but the design was faulty and the pyramid collapsed under its own weight, necessitating hasty alterations to its counterpart at Dahshur. Not until the IV Dynasty were all the problems solved and a sheer-sided true pyramid arose at Giza. After two more perfect pyramids, less resources and care were devoted to the pyramid fields of Abu Sir and South Saqqara, and the latterday pyramids near Fayoum Oasis never matched the standards of the Old Kingdom.

Their enigma has puzzled people ever since. Whereas the ancient Greeks vaguely understood their function, the Romans were less certain; medieval Arabs believed them to be treasure houses with magical guardians, and early European observers reckoned them the Biblical granaries of Joseph. The nineteenth century was a golden era of discoveries by Belzoni, Vyse, Petrie, Mariette, Maspero and Lepsius, which all suggested that the pyramids were essentially containers for royal tombs and nothing else. It was also the heyday of Pyramidologists like Piazzi Smyth and David Davidson, who averred that their dimensions in "pyramid inches" proved the supremacy of Christianity and the Jewish origin of the pyramid-builders.

Archeologists now agree that the pyramids' function was to preserve the pharaoh's ka , or double: a vital force which emanated from the sun-god to his son, the king, who distributed it amongst his subjects and the land of Egypt itself. Mummification, funerary rituals, false doors for his ba (soul) to escape, model servants ( shabti figures) and anniversary offerings - all were designed to ensure that his ka enjoyed an afterlife similar to its former existence. Thus was the social order perpetuated throughout eternity and the forces of primeval chaos held at bay, a theme emphasized in tomb reliefs at Saqqara. On another level of symbolism , the pyramid form evoked the primal mound at the dawn of creation, a recurrent theme in ancient Egyptian cosmogony, echoed in megalithic benben and obelisks whose pyramidal tips were sheathed in glittering electrum.

Although the limestone scarp at the edge of the Western Desert provided an inexhaustible source of building material, finer stone for casing the pyramids was quarried at Tura across the river, or came from Aswan in Upper Egypt. Blocks were quarried using wooden wedges (which swelled when soaked, enlarging fissures) and copper chisels, then transported on rafts to the pyramid site, where the final shaping and polishing occurred. Shipments coincided with the inundation of the Nile (July-November), when its waters lapped the feet of the plateau and Egypt's workforce was released from agricultural tasks.

Herodotus relates that a hundred thousand slaves took a decade to build the causeway and earthen ramps, and a further twenty years to raise the Great Pyramid of Cheops. Archeologists now believe that, far from being slaves, most of the workforce were actually peasants who were paid in food for their three-month stint (papyri enumerate the quantities of lentils, onions and leeks), while a few thousand skilled craftsmen were employed full time on its construction . One theory holds that a single ramp wound around the pyramid core, and was raised as it grew; when the capstone was in place, the casing was added from the top down and the ramp was reduced. Other ramps (recently found) led from the base of the pyramid to the quarry. Apparently, pulleys were only used to lift the plug blocks that sealed the corridors and entrance; all the other stones were moved with levers and rollers. It is estimated that during the most productive century of pyramid building, some 25 million tons of material were quarried. To put this in perspective, this is equivalent to one month's quarrying in Britain - or the material for 125 miles of motorway.

Whether or not the ancient Egyptians deemed this work a religious obligation, the massive levies certainly demanded an effective bureaucracy. Pyramid-building therefore helped consolidate the state. Its decline paralleled the Old Kingdom's, its cessation and resumption two anarchic eras (the First and Second Intermediate Periods) and the short-lived Middle Kingdom (XII Dynasty). By the time of the New Kingdom, other monumental symbols seemed appropriate. Remembering the plundered pyramids, the rulers of the New Kingdom opted for hidden tombs in the Valley of the Kings