Giza

Tallest for three thousand eight hundred and fifty years

The Great Pyramid of Khufu at Giza held the title of tallest structure on Earth from its completion around 2 540 BC until Lincoln Cathedral overtook it in AD 1311.

Three thousand eight hundred and fifty years.

It rose to an original height of 146.6 metres (today 138 metres, the missing nine being the lost capstone and outer casing) on a square base of 230 metres a side. The arithmetic is staggering: 2.3 million limestone blocks averaging 2.5 tonnes each, plus an internal core of larger granite slabs from Aswan 800 kilometres upriver, all placed in roughly twenty years of work.

Paid labour, not slaves

The Hollywood image of slaves dragging blocks under the lash is a modern invention.

In the 1990s the Egyptian archaeologist Zahi Hawass excavated the workers' village south of the pyramids and found barracks for about 20 000 men, central bakeries producing bread for tens of thousands of meals a day, and slaughter yards processing 11 cattle and 33 sheep daily — enough to feed the workforce beef and lamb regularly. The workers' cemetery showed decent dental health and adult longevity. Inscribed graffiti in the pyramid's relieving chambers names the construction gangs: Friends of Khufu, Drunkards of Menkaure. The cheerful tone of paid labourers who took pride in their work.

The arithmetic of standing up

Each side of the pyramid faces a cardinal direction to within three-sixtieths of a degree. The base is level across 230 metres to within 2.1 centimetres. The four corners are square to within a fraction of a degree.

None of these tolerances are accidental.

They imply systematic surveying using sighting poles, water-filled trenches as levels, and astronomical observations of circumpolar stars to align the structure with true north. The casing stones — once a gleaming polished white limestone covering the entire pyramid — were fitted with joints so tight that a knife blade cannot enter between them.

What happened to the white casing

The Great Pyramid looked very different when finished.

It was brilliant white, polished to a mirror finish under the desert sun, and visible to ships fifty kilometres out in the Mediterranean. The casing stones survived intact for thousands of years until the fourteenth century AD, when a magnitude-7 earthquake in Cairo loosened them.

The Mamluk sultans then quarried the casing for building stone. Most of medieval Cairo, including the mosque of Sultan Hassan, is built from the Great Pyramid's outer skin. Only a handful of casing stones still survive at the base, hinting at what the building once looked like.