Your turn
Each lab is one step from the video. Slide, tap and test the ideas yourself.
Each lab isolates one piece of the evidence. The models are simplified; see the notes.
Tap the buttons and slide the sliders.
Change how many years the build took. How many blocks a day is that?
2.3 million blocks ÷ (years × 365), over a ten-hour day. Lehner's own estimate is about 340 a day.
Slide it. Watch the pyramid go up!
Blocks a day = 2,300,000 ÷ (years × 365); minutes per block over a ten-hour working day.
Tap each clue. What does it tell us about who built the pyramid?
Cemetery, skeletons, settlement and graffiti: each is independent evidence against the slave myth.
Tap a clue. Who built the pyramid?
Tap each kind of stone to follow its journey on the map.
Local core limestone, Tura casing across the Nile, and Aswan granite far upriver.
Tap a stone. Watch it travel!
Map not to scale.
Pour water with the slider and count how many pullers you need.
Friction falls to about half at the optimum wetness, then rises again (Fall et al. 2014).
Slide to add water. Do you need more pullers, or fewer?
Pullers: about 8 for a 2.5-tonne block on wetted sand (Stocks), so about 16 on dry sand. The rise past the optimum is drawn qualitatively.
Try each ramp design and weigh up its strengths and problems.
The straight ramp is drawn to true scale at 1 in 10 against the pyramid's height.
Drag the slider to build the pyramid, course by course. How much stone is in place a third of the way up?
Share of volume below height fraction h = 1 − (1 − h)³.
Slide it and build the pyramid!
Long, long ago, in Egypt, people built giant pyramids by hand. The biggest one, the Great Pyramid, was made for a king called Khufu. It is made of lots and lots of stone blocks, and one block is heavier than a car!
Egyptian workers built them. They were paid and fed. They lived in a busy town with bakeries, ate bread and meat, and took turns working. When workers got hurt, they were cared for. Their teams had proud names, like "Friends of Khufu".
Most of the stone came from a quarry right next door. Workers cut it with copper tools and stone hammers. Shiny white stone came by boat on the river Nile.
Workers pulled the blocks on wooden sleds. A worker poured water on the sand in front of the sled. Wet sand stays firm, so only half as many people were needed to pull!
Workers built ramps, like big sloping paths, to drag blocks up high. Most of the stone went at the bottom, where the pyramid is widest.
The pyramids of Giza were built about 4,500 years ago by teams of paid, well-fed Egyptian workers, not slaves or aliens.35 They cut limestone blocks with copper chisels and stone hammers,5 floated heavier and finer stone down the Nile by boat,6 dragged blocks on wooden sledges over wetted sand,78 and raised them with ramps of mud brick, rubble and earth, using levers near the top.110
We know most of this from real evidence: the workers' town and cemetery, their tools, the quarries, and even a 4,500-year-old logbook. The one part experts still argue about is exactly how the ramps were arranged.110
The Great Pyramid was built for King Khufu, the second king of Egypt's 4th dynasty. It is the largest of the three pyramids at Giza.1
| Measurement | Great Pyramid of Khufu |
|---|---|
| Original height | 147 m (481 ft); about 138 m today |
| Each side of the base | about 230 m (756 ft) |
| Number of blocks | about 2.3 million |
| Average block | about 2.5 tonnes (heavier than a car) |
| Heaviest blocks | granite ceiling beams of 25 to 80 tonnes |
| Total weight | about 5.75 million tons |
| Slope of the sides | 51°52′, lined up with north, south, east and west |
If it took 20 years, the builders had to set about 315 blocks a day. That's one block every two minutes, all day, for two decades.13 Egyptologist Mark Lehner worked out a similar figure of about 340 stones a day.3
2,300,000 blocks ÷ (20 years × 365 days) ≈ 315 blocks a day
For centuries people assumed slaves built the pyramids. The evidence says otherwise. In 1990 a tourist's horse stumbled on a low mud-brick wall south of the Sphinx. Archaeologist Zahi Hawass dug there and found the cemetery of the pyramid workers: about 600 people, with the tombs of overseers surrounded by the simpler tombs of labourers.53 Being buried with honour right beside the king's pyramid is not how slaves were treated.
The skeletons tell a story too. Some workers had broken hands that had been splinted with wood, and one man had a leg operation and lived another 14 years.3 Injured workers got medical care.
Nearby, Mark Lehner excavated a whole workers' town, sometimes called the Lost City. It had long sleeping halls for about 1,600 to 2,000 people (perhaps twice that if they had two levels), scores of bakeries, and piles of bones from prime beef, sheep and goats.45 The workers were fed well.
Crews even left graffiti on the blocks with their team names, such as "Friends of Khufu" and the "Drunkards of Menkaure". Crews were organised into gangs and smaller teams, and people rotated in for a stint of work and then went home.34
The Greek historian Herodotus said 100,000 men, but he was writing about 2,000 years after the pyramid was finished. Modern estimates are about 20,000 workers, including support staff such as bakers, with roughly 10,000 doing the quarrying, hauling and setting.134
Workers cut soft limestone with copper chisels, stone hammers and wooden mallets. They had no iron.511
In 2013, archaeologist Pierre Tallet found the oldest papyrus scrolls ever discovered at an ancient harbour called Wadi al-Jarf, on the Red Sea. One was the logbook of an official named Merer, who led a crew of about 200 men. He records loading his boats with limestone at Tura and sailing it to Giza, in the 27th year of Khufu's reign.611 The Egyptians dug canals and a harbour so boats could reach close to the building site.6
On land, blocks rode on wooden sledges pulled with ropes. A wall painting in the tomb of Djehutihotep shows a giant statue on a sledge, with a man standing at the front pouring water onto the sand.89
In 2014, physicists at the University of Amsterdam tested why. On dry sand, a heap of sand builds up in front of the sledge. With the right amount of water, tiny water bridges glue the grains together, so the sand becomes about twice as stiff and the heap never forms. That halves the pulling force, so half as many people are needed.789 Too much water, though, and the friction goes up again.7
Most Egyptologists think the builders used ramps of mud brick, rubble and earth, with levers to help with the last, highest blocks. But no ramp survives in place, so the exact layout is still debated.110
| Ramp idea | Strength | Problem |
|---|---|---|
| One straight ramp | Simple | At a 1-in-10 slope it would need to be about 1.5 km long, bigger than the pyramid |
| Zigzag up one face | Much shorter | Tight turns for long hauling teams |
| Spiral around the sides | Uses less material | Little archaeological evidence; awkward turns at every corner |
| Internal ramp (Houdin) | Explains why no ramp remains | Unproven; many experts doubt it |
There is a real clue from Khufu's own time. At the Hatnub alabaster quarry, archaeologists from the University of Liverpool and the French Institute (IFAO) found a steep ramp with a staircase on each side and rows of post holes. Workers may have looped ropes around wooden posts to haul sledges up slopes of 20% or more.1012
A pyramid is widest at the bottom, so most of its stone sits low down. By the time the builders were one third of the way up, about 70% of all the stone was already in place. The share below any height fraction h is:
stone placed = 1 − (1 − h)³ → at h = ⅓, that's about 70%
The last blocks were few, but they had to be lifted the highest.
The pyramids were royal tombs. Each was part of a complex with temples and a causeway to the Nile valley.2 Egyptians believed the pyramid helped the king's spirit live on after death, which they thought kept the world in order.5 Building it drew in the whole country: granite from the south, food from the delta and limestone from Tura. Workers who rotated through Giza went home having seen their nation work as one.46
Teams of Egyptian workers cut limestone blocks with copper chisels and stone hammers, moved them on wooden sledges and by boat along the Nile, and raised them with ramps of mud brick, rubble and earth, using levers for fine positioning near the top.
We know a lot: who the workers were, where they lived, where the stone came from, what tools they used and how blocks travelled. The part still debated is exactly how the ramps were arranged to lift blocks to the top. Several designs are possible and none has been proven.
No. The evidence points to paid, well-fed Egyptian workers who served in rotating crews. They were buried in their own tombs beside the pyramids, some with injuries that had been treated, and their gangs had proud names like "Friends of Khufu".
The Greek writer Herodotus claimed 100,000 men, but he visited about 2,000 years later. Modern Egyptologists estimate around 20,000 workers including support staff such as bakers, with perhaps 10,000 doing the heavy stonework at any time.
The Great Pyramid is thought to have taken about 20 years, during the reign of King Khufu around 4,500 years ago. That works out at more than 300 blocks set every day.
They were royal tombs. Egyptians believed the pyramid and its temples would help the king's spirit live on after death, which they thought kept the whole world in order.
Yes. Experiments with copper tools, sledges and levers show ancient methods work. With modern cranes and trucks a pyramid would be far quicker, but cutting and placing 2.3 million blocks would still be a huge and expensive project.