The construction of the Egyptian pyramids can be explained using scientific facts, but some details remain debated. The methods used to build pyramids changed over time, with later pyramids not being built the same way as earlier ones. Scientists believe large stones were cut from quarries using copper tools and then moved and raised into place. People still disagree about how the stones were transported and placed.
There are also debates about who built the pyramids. Long ago, the Greeks thought slaves did the work. However, modern archaeologists believe the Great Pyramid of Giza was built by many skilled workers who lived near the pyramids and were paid or worked as part of a tax requirement. Evidence includes worker cemeteries found in 1990. For the Middle Kingdom pyramid of Amenemhat II, records show that workers from Canaan were used.
Some people study pyramids with theories that are not based on scientific evidence. These ideas are part of a field called pyramidology.
Historical hypotheses
The first written records about how these monuments were built came many years after the time when pyramids were constructed. These records were written by Herodotus in the 5th century BC and Diodorus Siculus in the 1st century BC. Herodotus described a method involving a machine, now called the "Herodotus Machine," and explained:
The pyramid was built in steps, which some called steps and others called tiers. After the first level was completed, workers used short wooden logs as levers to lift stones. They raised the stones from the ground onto the first tier, then used another lever on that tier to move the stones to the next level. It is unclear whether each tier had its own lever or if they used a single portable lever that they carried to each tier. However, it is certain that the top part of the pyramid was built first, followed by the next level, and finally the base.
Diodorus Siculus wrote:
It is said that the stones were brought from a place called Arabia, which at that time referred to the land between the Nile and the Red Sea, where limestone was quarried. The buildings were raised using earthen ramps because lifting machines had not yet been invented. It is surprising that no traces of these ramps or the stone dressing remain, even though the pyramids were built in an area covered with sand. Some Egyptians claimed the ramps were made of salt and natron, which melted when the river was redirected, leaving no evidence. However, this is not true. Instead, the same workers who built the pyramids later returned the stones to their original place. They say 360,000 workers were used for 20 years to complete the structure.
Diodorus's description of the stone being transported from Arabia is accurate because "Arabia" at that time included the area near the Nile where limestone was quarried.
In the earliest period, pyramids were built entirely of stone. Locally quarried limestone was used for the main parts of the pyramids, while higher-quality limestone from Tura (near modern Cairo) was used for the outer covering. This limestone came from the Eocene-aged Mokattam Formation. Granite from Aswan was used for parts like the portcullis (a type of gate) and the burial chamber’s walls and roof. Occasionally, granite was also used for the outer casing, as seen in the Pyramid of Menkaure. Early pyramids had sloping layers of stone, but later pyramids used horizontal layers. The Bent Pyramid at Dahshur shows a transition between these two methods, with its lower part built with sloping layers and its upper part with horizontal layers.
During the Middle Kingdom, pyramid construction changed again. Most pyramids built then were large mounds of mud-brick covered with polished limestone. In some cases, pyramids were built on natural hills to reduce the amount of material needed. The materials and methods used in early pyramids have helped them survive in better condition than later pyramids.
The stones forming the core of the pyramids were roughly cut, especially in the Great Pyramid. To fill gaps, large amounts of gypsum and rubble were used. This filling material had little binding strength but was necessary to stabilize the structure. To make the gypsum mortar, it had to be heated to remove water, which required large amounts of wood. Studies from the 1984 and 1995 David H. Koch Pyramids Radiocarbon Projects suggest that Egypt may have used up all its forests to build the pyramids of Giza and earlier 4th Dynasty pyramids. Carbon dating results from these studies showed dates that were 374 years earlier than previously accepted in 1984 and 100–200 years earlier in 1995. Researchers noted that the older dates might be due to the use of recycled wood and materials from earlier times, which could have affected the dating results.
The main material used during the Old and Middle Kingdoms was arsenical copper or bronze. This material is stronger than regular copper and can be made harder by hammering. Hundreds of artifacts from these periods were made of this material. Recently, preserved copper alloy tools from the Old Kingdom were collected in a study. This material was also found in settlements from Giza during the reigns of Khufu and Khafre. Recent findings from Middle Kingdom Elephantine Island show that this alloy was intentionally produced using complex technology.
Quarrying
Important information is available about the location of the quarries, the tools used to cut stone, how the stone was transported to the monument, how the foundation was leveled, and how the upper levels of the structure were leveled. Workers likely used copper chisels, drills, and saws to cut softer stones, such as most limestone. Harder stones, such as granite, granodiorite, syenite, and basalt, could not be cut using only copper tools. Instead, workers used methods like pounding with dolerite, drilling, and sawing with the help of an abrasive material, such as quartz or corundum sand. This process is called sand abrasion. Stone blocks were moved using sledges that were probably lubricated with water.
Leveling the foundation may have been done using water-filled trenches, 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 includes a drawing of 172 men pulling an alabaster statue of him on a sledge. The statue weighed about 60 tons. Denys Stocks estimated 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 a method to roll stones using a cradle-like machine found in New Kingdom temples. Four of these machines could be placed around a block to make it easier to roll. Tests by the Obayashi Corporation showed that 18 men could drag a 2.5-ton concrete block over a 1-in-4 incline ramp at a speed of 18 meters per minute. This idea was described earlier by John Bush in 1977 and mentioned in Parry’s book. Vitruvius in De architectura wrote about a similar method for moving heavy objects. 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 they disagree about how larger blocks were moved.
The diary of Merer, written over 4,500 years ago by an Egyptian official and discovered in 2013 in a cave in Wadi al-Jarf by a French team led by Pierre Tallet, describes moving limestone blocks from Tura quarries to Giza by boat.
Most Egyptologists believe ramps were the most likely way to move blocks up, but they admit this method is incomplete and needs another tool. Evidence of ramps has been found at the Great Pyramid of Giza and other pyramids. The most accepted way to help ramps was using levers. However, archaeological evidence shows only small ramps and inclined paths, not large ones that could have built most of the pyramids. There is also evidence that builders used unusual or non-standard methods.
Because of this, many different ramp designs have been proposed, but there is disagreement about which was used. A large straight ramp is widely dismissed due to its size, lack of evidence, and high labor costs. Other ramps, like zigzagging, straight ramps using parts of the pyramid, spiraling ramps supported by the pyramid, and spiraling ramps leaning on the monument, have been suggested. Mark Lehner thought a spiral ramp starting at the quarry and wrapping around the pyramid might have been used. However, spiral ramps would have covered the pyramid for years and made it hard to maintain the exact shape of the pyramid. Ramps with multiple paths inside step pyramids require less material. Blocks may have been pulled on sleds along ramps lubricated with water.
A recent study shows that builders had to move stones quickly—about 1 ton every 2–3 minutes using human teams on a ramp with a 10% slope—to complete the Great Pyramid in 30 years. Evidence from the E2 and E3 extensions of the Meydum pyramid shows that a small ramp system worked well. The shape of the pyramid, which becomes narrower as it rises, made it harder to build ramps. The Bent Pyramid’s slope change may have been due to the difficulty of using steep ramps. Effective organization of the construction site, with teams working on plots and transport paths between ramps and work areas, was also important. Bypass systems may have helped move stones to the top of the pyramid.
Levering is considered a possible way to help ramps, partly because of Herodotus’s description and the shadoof, a lever-based irrigation tool used in ancient Egypt. Mark Lehner suggested levers could lift the top 3% of the pyramid’s structure, which makes up about one-third of the monument’s height. Some levering methods lift blocks step by step, using wooden or stone shims to move them up one level at a time. Others use a large lever to lift a block in one motion. Experiments by Isler, Keable, and Hussey-Pailos tested these methods. Isler’s method took about 1.5 hours to lift a block one tier, while Keable’s method using concrete shims 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. This method was tested with weaker materials than those used in ancient Egypt but could work alongside ramp and levering techniques.
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 water levels around 4,500 years ago helped build the Giza Pyramid Complex. Today’s Nile waterways are too far from the pyramids to be useful. A 2024 study mapped an extinct branch of the Nile, the Ahramat Branch, which once flowed near the Great Pyramid and other Giza monuments. Using satellite imaging and sediment analysis, researchers confirmed the branch’s existence.
Pyramid building experiments
In 1978, Nippon TV supported a pyramid-building project planned by archaeologist Sajuki Yoshimura. The project was originally intended to be a 1 to 5 scale model of the Great Pyramid. However, due to a limited budget and rising limestone costs as the project became more public, the size had to be made much smaller. The chosen site lacked solid rock, so a concrete foundation was poured. Using two cranes and a forklift, workers built a pyramid 11 metres (36 ft) tall with a base 15 metres (49 ft) wide. The structure was later taken apart and removed.
In 1992, Egyptologist Mark Lehner and stonemason Roger Hopkins built a pyramid for a Nova television episode. The pyramid was 6 metres (20 ft) high and 9 metres (30 ft) wide, with a total volume of 162 cubic metres (5,700 ft ), 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 men assembled the structure. Modern tools like iron hammers, chisels, and levers were used, unlike the copper and wood tools ancient Egyptians relied on. Experiments with copper tools showed they could work if enough workers were available to resharpen them regularly, requiring about 20 additional workers. A front-end loader was used, but no modern machinery completed the construction. Levers helped lift the capstone to 20 feet (6.1 m). Smaller stones were moved using levers, 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 needed to be imported from Lebanon, as ancient Egypt had little available wood. While the builders did not perfectly copy the ancient Egyptians’ precise stone joints, Hopkins believed this could have been achieved with more practice.
Great Pyramid
Some research provides different estimates for the number of workers who built the Great Pyramid. For example, physicist Kurt Mendelssohn thought there may have been no more than 50,000 men working on the project. Other researchers, like Ludwig Borchardt and Louis Croon, believed the number was about 36,000. Miroslav Verner suggested that no more than 30,000 workers were needed. Evidence shows that about 5,000 workers were permanent employees who received salaries, while others worked for three or four months in exchange for food, such as ten loaves of bread and a jug of beer each day. Zahi Hawass believes many of the workers may have been volunteers. Most archaeologists agree that only about 4,000 workers were laborers who cut stone, moved blocks, and placed them in the pyramid. The rest of the workforce included people who provided support, such as scribes, toolmakers, and other helpers. The tombs of supervisors have inscriptions that describe how the workforce was organized. There were two groups of about 2,000 workers each, divided into named teams of 1,000. These teams were split into five groups of 200, which were further divided into smaller groups of about 20 workers based on their skills. Each small group had its own leader and a specific task.
A construction study by the firm Daniel, Mann, Johnson, & Mendenhall, along with Egyptologists like Mark Lehner, estimated that the project required an average of 14,567 workers and a maximum of 40,000 at one time. Without using pulleys, wheels, or iron tools, the researchers used a method called critical path analysis to estimate that the Great Pyramid was built in about 10 years. They calculated that between 2 and 2.8 million blocks were used in construction, with an average of 2.4 million. After subtracting the volume of empty spaces inside the pyramid, they estimated the final number of blocks used was about 2 million. Most sources agree that the number of blocks used was more than 2.3 million. Their calculations suggest that workers could place 180 blocks per hour (3 blocks per minute) during ten-hour workdays. These estimates were based on modern construction projects in areas without advanced machinery, but the exact method used to build the Great Pyramid is still unknown. Dr. Craig Smith of the team said:
The construction at the Giza site is amazing when you consider that the ancient Egyptians did not use pulleys, wheels, or iron tools. Yet, the pyramid’s dimensions are very precise, and the entire base of the 13.1-acre site was leveled to within a fraction of an inch. This level of accuracy is similar to what modern construction methods and laser leveling can achieve. It is incredible that ancient builders, using simple tools, reached such precision.
The entire Giza Plateau is believed to have been built during the reigns of five pharaohs in less than 100 years. This includes the Great Pyramid, the pyramids of Khafre and Menkaure, the Great Sphinx, Valley Temples, 35 boat pits carved into bedrock, several causeways, and large stones used to pave the plateau. It does not include the northern pyramid of Djedefre at Abu Rawash, which was also built during this time. Before the Giza Plateau was built, between 2687 and 2667 BC, four other large pyramids were constructed: the Step Pyramid of Saqqara, the Pyramid of Meidum, the Bent Pyramid, and the Red Pyramid. During the same period, the Sadd el-Kafara dam, which used about 100,000 cubic meters of rock and rubble, was also built.
In October 2018, archaeologists from the Institut Français d'Archéologie Orientale and the University of Liverpool discovered the remains of a 4,500-year-old ramp system at Hatnub. This system, which helped move heavy alabaster stones from quarries, may have been used to build the Great Pyramid as well. Yannis Gourdon, co-director of the project, explained:
This system includes a central ramp with two staircases and wooden posts. Ancient Egyptians used a sled attached to ropes to pull stones up steep slopes of 20% or more. Since this system dates back to the time of Pharaoh Khufu, it shows that Egyptians knew how to move large stones using steep slopes. They may have used this method to build his pyramid.
Jean-Pierre Houdin, an architect, developed a theory about how the Great Pyramid was built. His father, also an architect, thought of a method in 1999 that seemed more logical than other ideas. To test this, Houdin created a detailed computer model of the Great Pyramid. His plan involves using an external ramp to build the first 30% of the pyramid and an internal ramp to move stones higher. The stones from the external ramp were reused in the upper parts of the pyramid, which explains why no ramp remains were found.
After four years of working alone, Houdin collaborated with engineers from Dassault Systèmes, a French company that uses advanced computer technology. Together, they refined and tested the theory, making it the only one proven to be a viable method. Houdin published his findings in books in 2006 and 2008.
In Houdin’s method, each internal ramp ended at an open space, a temporary gap in the pyramid’s edge. This space held a crane that lifted and rotated 2.5-ton blocks, preparing them for eight workers to drag up the next internal ramp. In 2008, Houdin’s co-author, Bob Brier, discovered a previously unknown chamber that may be the start of an internal ramp. In 1986, a member of a French team saw a desert fox near this gap, suggesting it might have climbed inside.
Houdin’s theory has not been proven. In 2007, Egyptologist David Jeffreys called the idea of an internal spiral “far-fetched and overly complicated,” while John Baines of Oxford University said he was “suspicious of any theory that only explains how the Great Pyramid was built.”
Houdin also proposed that the Grand Gallery inside the pyramid was used