The building of the Egyptian pyramids can be explained using scientific facts, but some details are still debated by scientists. The methods used to build pyramids changed over time; later pyramids were not made the same way as earlier ones. It is thought that large stones were cut from quarries using copper tools, and these stones were then moved and raised into place. Scientists disagree mainly about how the stones were transported and positioned.
In addition to debates about building methods, there are also disagreements about who built the pyramids. Many years after the pyramids were built, the Greeks believed slaves were used. However, modern archaeologists believe that the Great Pyramid of Giza was constructed by thousands of skilled workers who lived near the pyramids and were paid or required to work as part of a tax until the project was finished. Evidence for this includes worker cemeteries found in 1990. For the Middle Kingdom pyramid of Amenemhat II, a stone record from the king shows that people from Canaan were employed.
Some unscientific theories, called pyramidology, try to explain how the pyramids were built. These ideas are not supported by strong evidence and are considered part of fringe archaeology.
Historical hypotheses
The first written records about how these monuments were built were written many years after the time when pyramids were constructed. These records were made by Herodotus in the 5th century BC and Diodorus Siculus in the 1st century BC. Herodotus described a method that involved using wooden logs as levers to lift stones. He explained that after the base of the pyramid was built, workers used short wooden logs to raise stones from the ground to the first tier. Once the stones reached the first tier, they were moved to another lever on that tier to lift them to the next level. It is unclear whether each tier had its own lever or if workers carried a single portable lever to each tier. However, Herodotus was certain that the top part of the pyramid was built first, followed by the lower sections, and finally the base.
Diodorus Siculus wrote that the stones used in the pyramids were brought from a region called Arabia, which, at that time, referred to the land between the Nile River and the Red Sea. He claimed that workers used earthen ramps to move the stones because lifting machines had not yet been invented. He was surprised that no evidence of these ramps or the stone-cutting tools remains, as the area is covered with sand. Some Egyptians suggested that the ramps were made of salt and natron, which dissolved when the Nile River was redirected, leaving no trace. However, Diodorus argued that the pyramids were built by thousands of workers over twenty years, not by divine intervention.
During the earliest period, pyramids were made entirely of stone. Local limestone was used for the main body of the pyramids, while higher-quality limestone from Tura, near modern Cairo, was used for the outer covering. This limestone came from ancient deposits known as the Mokattam Formation. Granite, quarried near Aswan, was used for parts like the portcullis (a type of gate), the burial chamber’s walls and roof, and occasionally for the outer covering, as seen in the Pyramid of Menkaure. Early pyramids had stone layers (called courses) that sloped inward, but later pyramids used horizontal layers. The Bent Pyramid at Dahshur shows a transition between these two methods, with its lower section sloping and its upper section horizontal.
During the Middle Kingdom, pyramid-building changed again. Most pyramids from this time were made of mud bricks covered with polished limestone. In some cases, pyramids were built on natural hills to reduce the amount of material needed. The construction methods used in earlier pyramids have helped them survive in better condition than later pyramids.
The core stones of the pyramids were roughly shaped, especially in the Great Pyramid. To fill the gaps between stones, large amounts of gypsum and rubble were used. This filling material did not bind the stones together but was necessary to stabilize the structure. To make the gypsum mortar, it had to be dried by heating, which required large amounts of wood. Studies from 1984 and 1995 suggest that Egypt may have used up most of its forests to build the pyramids of Giza and other pyramids from the 4th Dynasty. Carbon dating results from these studies showed that some dates were 374 years earlier than previously believed, and others were 100–200 years earlier. Researchers suggested that the use of old wood, possibly from earlier times, might explain these discrepancies.
The main material used in the Old and Middle Kingdoms was a type of copper mixed with arsenic, called arsenical copper or bronze. This material was stronger than regular copper and could be made even harder by hammering. Many tools and artifacts from these periods were made of this alloy. Recent studies have confirmed that this material was used in the Giza settlement during the reigns of Khufu and Khafre. Evidence from Elephantine Island in the Middle Kingdom shows that this alloy was intentionally created using complex techniques.
Quarrying
There is useful information about the location of the quarries, the tools used to cut stone, how the stone was moved to the monument, how the foundation was leveled, and how the upper levels of the structure were made even. Workers likely used copper chisels, drills, and saws to cut softer stones, like most limestone. Harder stones, such as granite, granodiorite, syenite, and basalt, could not be cut with copper tools alone. Instead, workers used slow methods, such as pounding with dolerite, drilling, and sawing with the help of abrasive materials like quartz or corundum sand. This process is called sand abrasion. Stone blocks were probably moved using sledges that were lubricated with water.
Leveling the foundation may have been done by filling trenches with water, as suggested by Mark Lehner and I. E. S. Edwards, or by using a simple square level and skilled surveyors.
Transport of stone blocks
One of the main challenges for early pyramid builders was moving large amounts of stone. The Twelfth Dynasty tomb of Djehutihotep has a drawing showing 172 men pulling an alabaster statue of him on a sledge. The statue is estimated to weigh 60 tons. Denys Stocks calculated that 45 workers would be needed to move a 16,300 kg (35,900 lb) block that was lubricated, or eight workers to move a 2,750 kg (6,060 lb) block. Dick Parry and Mladjov suggested using a cradle-like machine found in New Kingdom temples. Four of these machines could be placed around a block to roll it easily. Experiments by the Obayashi Corporation showed that 18 men could drag a 2.5-tonne (5,500 lb) concrete block over a 1-in-4 incline ramp at a speed of 18 meters per minute. This idea was first described by John Bush in 1977 and later mentioned in Parry’s book. Vitruvius, in De architectura, described a similar method for moving irregular weights. It is unclear if Egyptians used this method, but experiments suggest it could have worked for blocks of this size. Most Egyptologists agree this method was likely used for 2.5-ton blocks but disagree on how heavier blocks, like those weighing 15+ tons or 70–80 tons, were moved.
The diary of Merer, written over 4,500 years ago by an Egyptian official and discovered in 2013 by a French team led by Pierre Tallet in a cave in Wadi al-Jarf, describes moving limestone blocks from Tura quarries to Giza by boat.
Most Egyptologists believe ramps were used to raise blocks, but they admit this method is incomplete and may need another tool. Evidence of ramps has been found at the Great Pyramid of Giza and other pyramids. The most accepted way to help ramps is by using levers. However, archaeological findings show only small ramps and inclined paths, not ones large enough to build most of the monument. There is also evidence that builders used non-standard methods.
Because of this, many different ramp designs have been proposed, but there is disagreement about which ones were used. One idea, a large straight ramp, is widely discredited because of its size, lack of evidence, and high labor costs. Other ramps, like zig-zagging ramps, straight ramps using parts of the pyramid structure, and spiraling ramps, have been suggested. Mark Lehner thought a spiraling ramp might have started in the quarry and wrapped around the pyramid. However, spiral ramps would have covered the building for years and made it hard to keep the pyramid’s exact shape. Ramps with multiple paths inside step pyramids may have used less material. Blocks may have been dragged on sleds lubricated with water.
A recent study shows that moving stones required not only planning the route but also handling the size and speed of transport. About one ton of stone had to be placed every 2–3 minutes by human teams on a ramp with a 10% slope to build the Great Pyramid in 30 years. The narrow, ring-shaped extensions of the E2 and E3 pyramids at Meydum suggest that the ramp system was small and effective. However, the pyramid’s geometry made it harder to build as it grew taller, reducing space for ramps. The Bent Pyramid’s slope change may have been due to the difficulty of using steep ramps. Organizing the construction site with clear work areas and transport paths between ramps and workspaces was also important. Bypass systems may have helped move materials to the final placement.
Levering methods are considered a good way to help ramps, partly because of Herodotus’s description and the use of the shadoof, a lever-based irrigation tool. Mark Lehner suggested using levers to lift the top 3% of the pyramid’s superstructure, which makes up one-third of the monument’s height. Some methods use levers to lift blocks step by step, inserting wooden or stone shims to move them slowly. Others use larger levers to lift blocks in one motion. Experiments by Isler, Keable, and Hussey-Pailos tested these methods. Isler’s method used wooden shims and took about 1.5 hours to lift a block one tier. Keable’s method used concrete shims and took about 2 minutes. Hussey-Pailos’s method used a simple lever to lift a 1,100 kg (2,500 lb) block in under a minute, even with weaker materials. This method works well with Lehner’s idea of combining ramps and levers.
The ancient Egyptians used a now-dried branch of the Nile to transport building materials. A 2012 study by Hader Sheisha at Aix-Marseille University suggested that higher river levels around 4,500 years ago helped build the Giza Pyramids. Today, the Nile’s waterways are too far from the pyramids to be useful. A 2024 study mapped the Ahramat Branch, an extinct Nile branch that once flowed near the Great Pyramid and other Giza monuments, using satellite imaging and sediment analysis.
Pyramid building experiments
In 1978, Nippon TV supported a pyramid-building project led by archaeologist Sajuki Yoshimura. The project was first planned to be a 1 to 5 scale model of the Great Pyramid. However, due to budget limits and rising limestone costs after the project became well-known, the size had to be significantly reduced. Since the chosen location lacked solid ground, a concrete foundation was built. Using two cranes and a forklift, workers constructed a pyramid 11 meters (36 feet) tall with a base 15 meters (49 feet) wide. The structure was later removed and taken away.
In 1992, Egyptologist Mark Lehner and stonemason Roger Hopkins built a pyramid for a Nova television episode as part of a three-week experiment. Their pyramid was 6 meters (20 feet) high and 9 meters (30 feet) wide, using 162 cubic meters (5,700 cubic feet) of material, or about 405 tons. It was made of 186 stones, each weighing an average of 2.2 tons. Twelve workers carved the stones in 22 days, and 44 people assembled the structure. Modern tools like iron hammers, chisels, and levers were used, unlike the copper, bronze, and wooden tools ancient Egyptians relied on. However, experiments with copper tools showed they could work if more workers were available to sharpen them regularly. An extra 20 workers would have been needed for this task. A front-end loader or forklift was used, but no modern machinery completed the construction. Levers helped lift the capstone to a height of 20 feet (6.1 meters). Smaller stones (less than one ton) were moved using levers and rolled, while larger stones were towed. By placing stones on wooden sledges and sliding them on wooden tracks, 12 to 20 workers could move a two-ton stone. The wood for these tools would have had to be imported from Lebanon, as ancient Egypt had little to no wood available. While the builders did not perfectly replicate the precise stone joints of ancient pyramids, Hopkins believed this could have been achieved with more practice.
Great Pyramid
Some studies offer different numbers for how many workers built the Great Pyramid. Physicist Kurt Mendelssohn thought the workforce may have had 50,000 men at most. Others, like Ludwig Borchardt and Louis Croon, believed the number was 36,000. Miroslav Verner suggested no more than 30,000 workers were needed. Evidence shows about 5,000 workers were permanent employees who received wages in the form of bread and beer. The rest worked short-term shifts in exchange for tax relief. Zahi Hawass believes many workers may have volunteered. Most archaeologists agree that only about 4,000 workers directly quarried and placed the stones. The majority of workers provided support roles, such as scribes and toolmakers. Tomb inscriptions show the workforce was organized into two crews of about 2,000 workers each. These crews were divided into named groups of 1,000, which were further split into five teams of 200. Each team was grouped by skill, with a leader assigned to each group.
A study by Daniel, Mann, Johnson, & Mendenhall and other Egyptologists estimated that the project needed an average of 14,567 workers and a peak of 40,000. Without pulleys, wheels, or iron tools, they used a method called critical path analysis to estimate the pyramid took about 10 years to build. The study suggests 2 to 2.8 million blocks were used, averaging 2.4 million. After subtracting the volume of hollow spaces, they estimated 2 million blocks were used. Most sources agree the number was above 2.3 million. They calculated workers could place 180 blocks per hour (3 blocks per minute) with 10-hour workdays. These estimates were based on modern construction projects without machinery, but the exact method used to build the pyramid remains unknown.
Dr. Craig Smith noted that ancient Egyptians built the pyramid with simple tools, yet achieved extreme accuracy. The pyramid’s base was leveled within a fraction of an inch over 13.1 acres, similar to modern construction methods.
The Giza Plateau was built during the reigns of five pharaohs in less than 100 years. This includes the Great Pyramid, Khafre and Menkaure’s pyramids, the Great Sphinx, Valley Temples, 35 boat pits, causeways, and large stone paving. It does not include Khafre’s brother Djedefre’s pyramid at Abu Rawash, which was also built during this time. Before Giza, from 2687 to 2498 BC, four other large pyramids were built: the Step Pyramid of Saqqara, the pyramid of Meidum, the Bent Pyramid, and the Red Pyramid. The Sadd el-Kafara dam, requiring 100,000 cubic meters of rock, was also built during this period.
In 2018, archaeologists discovered a 4,500-year-old ramp system at Hatnub. This system used a central ramp and wooden posts to pull heavy stones up steep slopes. Yannis Gourdon, a co-director of the project, said this method may have been used to build the Great Pyramid.
Jean-Pierre Houdin, an architect, proposed a construction method in 1999. He built a computer model showing an external ramp was used for the first 30% of the pyramid, with an internal ramp for higher sections. Stones from the external ramp were reused in the upper parts, explaining the lack of ramp evidence. Houdin worked with engineers from Dassault Systèmes to refine his model, which he published in books in 2006 and 2008.
Houdin’s plan included internal ramps ending at open spaces where cranes lifted blocks for workers to drag up. A chamber discovered in 2008 may be the start of one of these ramps. However, some Egyptologists, like David Jeffreys and John Baines, have criticized Houdin’s theory as overly complex.
Houdin also proposed the Grand Gallery acted as a guide for moving heavy granite beams that roof the King’s Chamber. His team proved cracks in these beams were examined and found harmless during construction. Houdin’s theories remain unproven but have sparked further research.