How Were the Pyramids Built? What the Evidence Shows

A building site, not a mystery

The Great Pyramid belongs to Khufu, a king of the Fourth Dynasty who reigned around 2589-2566 BCE. It was originally 146.6 metres high, the tallest building on earth for nearly four thousand years, with a square base about 230 metres a side and some 2.3 million blocks. Its sides face the four cardinal points with an error of about 4 minutes of arc, less than a fifteenth of a degree.

Numbers like these are the reason for all the theories about lost technologies. But the question “how?” has a lot of answers on the ground. Archaeologists have excavated the quarries, the ramps, the harbours, the workers’ town and the cemetery of the builders. Put together, they describe a building site: huge, very well organised, and entirely within the reach of Bronze Age Egypt.

Where did the stone come from?

Most of the stone was right there. The core blocks, a coarse local limestone averaging around 2.5 tonnes, were cut from quarries on the Giza plateau itself, a few hundred metres south of the pyramid. Two other materials came from far away. The fine white limestone of the outer casing was quarried at Tura, on the other side of the Nile, and the granite of the King’s Chamber came from Aswan, some 800 km upstream.

Both travelled by water. In 2013 a French mission led by Pierre Tallet and Gregory Marouard found the oldest inscribed papyri known, at Wadi al-Jarf, a harbour of Khufu on the Red Sea. Among them is the logbook of an inspector called Merer, written in the 27th year of Khufu’s reign. For months, Merer and a team of about 40 men sailed between Tura and Giza with blocks of casing stone, through canals and a basin connected to the Nile, under the authority of the king’s half-brother, the vizier Ankhhaf. According to Tallet’s estimate, each boat could carry around 30 casing blocks.

Tools that wore out

To cut limestone the workers used copper chisels and saws, along with wooden mallets. Copper is soft, so the edges blunted quickly and had to be sharpened and recast all the time, which means the building site had its own workshops. For hard stone such as granite, they pounded with balls of dolerite, a very hard rock, and sawed with copper blades fed with sand: the sand did the cutting, the blade only moved it. The work was slow, but there was plenty of labour, and in practice that made up for it.

How do you move a 2.5-tonne block?

On land, blocks travelled on wooden sledges. A painting in the tomb of Djehutihotep, a governor of the Middle Kingdom, shows a colossal statue on a sledge pulled by rows of men, with one man at the front pouring water on the sand. For a long time it looked like a ritual gesture. In 2014 physicists at the University of Amsterdam tested it and published the result in Physical Review Letters: sand with the right amount of water (a few per cent) becomes stiff and stops piling up in front of the sledge, so the force needed to drag it falls by about half. It works like wet sand on a beach, which holds the shape of a sandcastle while dry sand runs through your fingers.

To lift the blocks, the builders used ramps of mudbrick, rubble and earth. Nobody knows the exact layout used for the Great Pyramid, and several are possible: a long straight ramp, ramps wrapped around the faces, or short ramps combined with levers on the upper courses. In 2018, however, a team from the French Institute (IFAO) and the University of Liverpool found at the alabaster quarry of Hatnub a ramp of Khufu’s time with a steep central slope, a staircase on each side and rows of post holes. Ropes tied to the wooden posts let teams haul sledges up slopes of 20 per cent or more, which is much steeper than anyone expected.

Who built it?

Slaves, as so many films suggest? The evidence says otherwise. Since 1988 Mark Lehner and the AERA team have excavated, about 400 metres south of the Sphinx, a town of the pyramid builders known as Heit el-Ghurab: galleries where crews slept, bakeries, breweries, storerooms, offices for scribes and pens for cattle. The workers ate beef, sheep and goats as well as bread and beer. Higher up, from 1990, Zahi Hawass excavated their cemetery: small tombs built for themselves, with the titles of their crews and, in some skeletons, healed fractures, a sign of medical care.

The workforce was organised in crews with names, often cheerful ones, which still appear painted on the blocks, such as “Friends of Khufu”. A core of skilled workers was employed all year, and others joined on rotation. Estimates vary, but most scholars estimate some 20,000 to 25,000 people at the peak, not hundreds of thousands. In the same years the state also built the capital, Memphis, and its temples. The pyramids were a national enterprise, and they followed the rules of Egyptian art as strictly as any statue.

What is still unknown

The inside of the pyramid still holds surprises. Above the King’s Chamber, five low compartments, the so-called relieving chambers, spread the weight of the stone above. Since 2015 the ScanPyramids project has studied the pyramid with muons, particles produced by cosmic rays that cross stone and are absorbed more where it is denser. In 2017 the team announced in Nature a large empty space, the “Big Void”, at least 30 metres long, above the Grand Gallery. In 2023 a camera pushed through a gap confirmed a corridor about 9 metres long behind the north face. What these spaces were for is still unknown. The rooms open to visitors are described in our guide to the chambers and passages inside.

Where to see it

The Great Pyramid stands on the Giza plateau, on the western edge of Cairo, next to the pyramids of Khafre and Menkaure and the Sphinx. The remains of the casing are best seen at the base of the north side. Some of the Wadi al-Jarf papyri are displayed in Cairo; check the current display with the Egyptian Museum and the Grand Egyptian Museum before you visit.

Sources

• P. Tallet and G. Marouard, “The Harbor of Khufu on the Red Sea Coast at Wadi al-Jarf, Egypt”, Near Eastern Archaeology 77.1 (2014); P. Tallet, Les papyrus de la mer Rouge I (2017).
• A. Fall et al., “Sliding Friction on Wet and Dry Sand”, Physical Review Letters 112, 175502 (2014).
• University of Liverpool and IFAO, announcement of the Hatnub ramp (2018).
• K. Morishima et al., “Discovery of a big void in Khufu’s Pyramid by observation of cosmic-ray muons”, Nature 552 (2017); S. Procureur et al., Nature Communications 14 (2023).
• Ancient Egypt Research Associates (AERA), Heit el-Ghurab excavations; M. Lehner, The Complete Pyramids (1997).
• Harvard University, The Giza Project.