Yukinori Kawae on Khufu's Great Pyramid: Why It Was Built, Who Built It, and How

The program's narration begins by explaining how the pyramids came to be. About 4,600 years ago, royal tombs changed from mud-brick mastabas to huge stone step pyramids. Building technology then developed rapidly, and about 4,500 years ago the Great Pyramid of Khufu appeared at Giza.

According to Kawae, the pyramid we see today looks very different from how it did when it was built. Today the Great Pyramid's limestone is exposed, but originally its surface was covered with fine, pure white casing stones. These casing stones were stripped away in later periods and reused. As a result, it is thought that the pyramid was originally a beautiful square pyramid that reflected the sunlight. At the top sat a capstone, called the benben stone in ancient times, which was probably inlaid with electrum, an alloy of gold and silver. The narration also notes that at the time, the Nile's floods brought water close to the foot of the pyramid.

Kawae also stresses that the three great pyramids did not stand side by side from the start. In Khufu's time, Giza had only the one Great Pyramid. When Khafre then built the second pyramid, the landscape had two, and only when Menkaure, Khufu's grandson, built the third did they become the "three great pyramids." One, two, three: according to Kawae, each era had a different landscape. All three, he says, originally gleamed with casing stones.

Kawae says the natural environment of the time is also hard to imagine from today's arid land. Giza 4,500 years ago had more rain than it does now. As evidence, Kawae points to the remains of the pyramid town he himself excavated, that is, the settlement of the time. Examining the large mud-brick walls there reveals traces of bricks that were dissolved by rain.

The animal bones found there are another clue. People ate good-quality meat such as sheep, goat and cattle, and a little pork as well. They also ate large amounts of fish. In addition, bones of gazelle and hartebeest, animals that today would be seen in East Africa, have been found. From this, Kawae says one could describe the area around Giza at the time as an environment close to savanna.

Next, Kawae describes the interior, following the route a tourist takes into the Great Pyramid. The original entrance is currently closed. Tourists enter through a hole said to have been opened by al-Ma'mun, an Arab ruler of around the 9th century, in an attempt to plunder the pyramid. Following this hole leads to the Ascending Passage. Around its junction with the Ascending Passage, the Descending Passage, which heads downward, also connects.

The Descending Passage is extremely narrow, and in Kawae's words you go along crouched the whole way "like a punishment game." About 30 m below ground level, you reach the Subterranean Chamber. It is an unfinished room, and there are various theories about why. Some say it represents the underworld; others say the builders intended to build another room above it. But it is a dead end with nothing in it. The Descending Passage does not connect anywhere else, so you have no choice but to go back to the Ascending Passage.

You also climb the Ascending Passage crouching. After a while, you come out into the Grand Gallery, the largest space inside the pyramid. The ceiling is about 8.7 m high—roughly 9 m, as Kawae puts it—and narrows step by step using a technique called corbelling. He says it may feel mysterious to those entering for the first time. Climbing further up the Grand Gallery, at the far end, is the final room, the King's Chamber. The King's Chamber alone is made of a different stone: the whole room is granite, and it has a somewhat dark atmosphere.

Going horizontally from just before the Grand Gallery leads to the so-called "Queen's Chamber." However, no queen was actually buried there. Whereas the King's Chamber is made of dark red granite, this room is built of white limestone. Kawae explains that it was regarded as feminine for that reason and came to be called the Queen's Chamber in modern times.

Above the King's Chamber are five layered chambers known as the "Relieving Chambers." They are a place you cannot enter without special permission. The top is a triangular gabled structure that serves to distribute the weight pressing down from above. When the interviewer remarked, "That's complex, considering ancient technology," Kawae replied, "Insanely complex." Building such a huge and complex structure inside the pyramid rather than underground was unique to Khufu, he says.

As for the purpose of the pyramid, Kawae's answer is that it was, fundamentally, "a royal tomb." It is often said that the pyramids contain neither mummies nor treasure, but that is not limited to Khufu's pyramid. More than 70 pyramids have been found in the Memphis area, which is a World Heritage Site, but no king's mummy has ever been found intact. Kawae says this is because almost all ancient Egyptian royal tombs were plundered.

On the other hand, fragments of mummies and parts of canopic jars, which held the removed internal organs, have been found in other pyramids. The three great pyramids of Giza also have sarcophagi and places to hold canopic jars. From this, Kawae says it is "pretty much certain" that they were royal tombs. However, a pyramid was not simply a place to bury the king. It was also a structure closely tied to the Egyptians' worldview, including the creation of the cosmos—connected to sun worship, Osiris, god of the underworld, and the primeval mound from which the world was said to have emerged.

Why did royal tombs become so enormous? Kawae says we need to think about it from a broader perspective. About 500 years before the pyramids were built, the first state emerged in Egypt. For people today, having a country is taken for granted, but at the beginning, the very concept of a state did not exist.

According to the narration, once the state was established, systems of administration and taxation developed, and wealth collected from across the country came to be concentrated at the center. When they considered how to use that wealth, they decided to build tombs for the king. This is how Kawae explains why royal tombs grew ever larger over the roughly 500 years after the state was founded.

It used to be said that slaves built the pyramids. According to Kawae, this idea originates in The Histories by Herodotus, the "Father of History." Until Kawae was a child, the idea was widely repeated, and Hollywood films even depicted slaves being whipped as they built the pyramids.

However, the excavation of the pyramid town led by Kawae's mentor Mark Lehner found no such traces. What emerged instead was a society with very high consumption. In an experiment calculating the size of a single loaf from the large pots used to bake bread, the result was an ultra-high-calorie loaf of about 9,500 kilocalories. Kawae believes these loaves were distributed about once every four days. Large quantities of sheep and goat bones have also been found, meaning people ate meat once every two or three days. Kawae calls this "unbelievable" for ancient times. They also ate large amounts of catfish and tilapia caught in the Nile. In addition, traces have been found showing that Nile acacia was burned extensively as solid fuel. From all this, he says, we can infer that the builders lived quite well while building the pyramids.

Kawae does add a caveat, however. In a centralized state the king's power was absolute, and there is probably no doubt that people were gathered under that power. Even so, Kawae's view is that this differs from the image of whipped slaves.

The population of ancient times cannot be known precisely. One method is to work backward from the food supply. Kawae notes that by a very rough estimate, the population of the Old Kingdom was around 1 million to 3 million people.

There are various theories about how many people were involved in building the Great Pyramid. One estimate puts the figure at around 20,000 to 30,000. But not all of them were stacking stones on site. Because the area in which work could be done on site was limited, Kawae thinks that, judging from that, perhaps around 4,000 people actually worked on the pyramid itself. The others, he suggests, were probably involved in supplying food, transporting materials and so on.

According to the narration, construction began with choosing the site. Giza is not desert sand but a plateau made of limestone. It is thought that the ancient Egyptians used this plateau as part of the foundation and, by observing the stars and the sun, oriented the pyramid so that each side faced almost exactly north, south, east or west.

The quarry lies right next to the pyramid. Kawae says the availability of good stone on the Giza Plateau was probably one of the reasons the site was chosen. To cut stone, workers used hammerstones made of hard igneous rock such as diorite and simply pounded away by hand. As they kept pounding, the hammerstones themselves wore down and became rounded. Workers kept using them, changing the angle, and when they finally became perfectly round and unusable, they were thrown away. Archaeologists sometimes find these discarded hammerstones 4,500 years later.

Stones roughly shaped to some extent were carried to the construction site, where they were either worked again or, if their shape was already good, set in place as they were. Large stones were probably transported on sledges. Inside the pyramid there are also huge granite blocks of 60 to 70 tons brought from Aswan, near Egypt's southern border, several hundred km south of Giza. Kawae thinks these were probably moved on sledges. He says records depicting transport by sledge actually survive.

Ropes were used for setting the stones, but if a stone was too heavy, ropes alone could not move it. So workers cut notches into the stones and pushed them into place using leverage. Even that was hard work, so they spread mortar underneath to make the stones slide more easily. Once set, the mortar also acted as a kind of adhesive.

The way the chambers were built is also distinctive. Pyramid chambers are generally underground, carved out of the bedrock. But in the Great Pyramid, and in the Red Pyramid and Bent Pyramid built before it by Khufu's father Sneferu, the chambers alone are above ground level. Kawae explains that this means they were not carved out but rather the spaces were created at the same time as the pyramid was built up.

There are still several hypotheses about how the stones were stacked so high. Among them, Kawae answers that ramps are "pretty much certain," because ramps were a method used in ancient Egypt for thousands of years. Where opinions diverge is on the shape of the ramp.

Kawae is currently excavating a pyramid at Sinki, south of Abydos. It dates to the time of Khufu's father or grandfather, and Kawae notes that "Sinki" is a place name, not the Japanese word shinki meaning "new." Ramps survive on each of this pyramid's four faces, and it is known that stones were brought in from all four sides.

For the Great Pyramid, Kawae reasons from "context," the surrounding circumstances that archaeologists place great weight on. The Great Pyramid stands at the northern edge of the Giza Plateau, and directly to the north is a cliff, so no ramp could have been built there. To the east and west, royals and nobles began building mastaba tombs within a few years of the pyramid's construction. That leaves only the south side for a ramp. Moreover, a huge quarry remains on the south side. From this, Kawae thinks the pyramid was built up to a certain height using a straight ramp from the south, after which a spiral ramp was built around the outside of the pyramid.

In this scenario, the angle of the final ramp would approach 20 degrees, and some point out that this is too steep. But according to Kawae, examining other ramps from the same period shows that ramps with similar angles actually exist. Twenty degrees is therefore not an impossible angle, and as for weight, stones of around 2 to 3 tons could have been hauled without difficulty, he says.

The narration notes that the Great Pyramid is said to contain 2.3 million to 3 million stones averaging about 2.5 tons. However, because the size of the stones and the density of the interior are unknown, these are all estimates. Dividing this number by the estimated construction period of about 20 years, and assuming the stones were laid one at a time in sequence, gives a pace of one stone every few minutes.

Kawae rejects this calculation. They probably did not lay stones one at a time, he says. If stones were brought in batches, they might have laid ten at once, and they would have kept shaping and laying them one after another on the spot. Calculations like this end up being a kind of numerical magic or trick, Kawae says. The number of stones itself is not even known. Still, even by the calculations of experimental archaeologists, building it by human labor is said to be entirely feasible.

What Kawae really wants to know is the organizational power that brought people together and how people were mobilized. Experimental archaeology also shows that when many people pull on a rope, their force gets dispersed and it is difficult to pull all at once. The ancients were able to do it. As another example, Kawae cites records from about 100 years ago. When the Temple of Amun at Karnak, the largest temple in Egypt, was restored, people at the time moved fallen stones weighing dozens of tons without heavy machinery. Black-and-white photographs of this survive, and they show the stones being moved successfully. From this, Kawae thinks there must have been methods of coordinating people. Songs, for example. Chants like "eiyaho" are still commonly used today, and Kawae says there must have been something like that.

Asked whether ancient technology was more advanced than today's, Kawae answers, "No." Technologically, the present is superior. If a nation today could not build one, Kawae thinks it would be because doing so would be a major social and political problem.

As an actual estimate, Kawae cites one made around 1978 by Obayashi Corporation in its in-house magazine Kikan Obayashi. According to it, the pyramid could be built for 125 billion yen at the prices of the time, over a construction period of about five years. Kawae says it could probably be built today. But the effort and time it took to accomplish it with the technology of the time are on an entirely different level.

Kawae gives Khufu's sarcophagus as an example. Granite is commonly used for gravestones today, but at the time granite was reserved for the king alone. Khufu's coffin was made by hollowing out a block of granite. Today it could easily be hollowed out with synthetic diamond tools, but 4,500 years ago was the age of copper, when not only synthetic diamonds but even iron and bronze were not in common use. Asked how they hollowed it out, Kawae replied, "Sheer grit and determination, right?" According to experimental archaeology, hollowing out granite with copper tools takes 28,000 hours. Depending on how many teams the work was divided among, a single coffin probably took 9 to nearly 10 years, and Kawae says their sense of time was completely different.

The narration supplements this. Because copper cannot cut granite directly, the ancient Egyptians used quartz-bearing sand as an abrasive, working copper drills while pouring sand to grind away the stone little by little. Khufu's sarcophagus also bears tool marks thought to have been made by drills and tubular tools.

For a long time, the main spaces people could enter in the Great Pyramid were three: the Subterranean Chamber, the Queen's Chamber and the King's Chamber. There had long been talk of other rooms, but it never went beyond talk. The one that found such spaces scientifically was ScanPyramids, an international research team from Japan, France and Egypt that includes Nagoya University.

According to the narration, in 2017 the team announced that it had discovered an unknown space inside the Great Pyramid through imaging using muons. Muons are elementary particles created when cosmic rays collide with atoms in the atmosphere, and they rain down on the ground. They pass through even thick stone, but the thicker and denser the material, the fewer get through. The team therefore placed detectors inside the pyramid and measured the number and direction of incoming muons. As a result, they identified a region through which more muons passed than could be explained by the known structures. A separate space was also found near the north entrance in a similar survey in 2016, and in 2023 the team succeeded in filming its interior with an endoscope.

As Kawae explains, above the Grand Gallery is a space of around 30 m, about the same size as the Grand Gallery, which the team calls the "Big Void." The corridor-like space found near the entrance is called the "North Face Corridor," and that is the one that was successfully filmed. The Big Void, on the other hand, lies at the center of the pyramid and cannot be physically reached; at present, the muon data merely suggest its existence. It is not somewhere you could reach by removing a single stone; the question becomes how many holes you would have to drill. And in the first place, the pyramid is a cultural property, so damaging it is not permitted. For these reasons, Kawae thinks direct confirmation of the Big Void will be difficult.

As for what is inside the Big Void, Kawae prefaces his answer with "I am curious about what's inside," then says he does not think anything is there. The most important part of the Great Pyramid is the King's Chamber. In building the King's Chamber, the overriding imperative was to bury the king's body there while ensuring that neither the pyramid nor its passages collapsed. Kawae speculates that the Big Void is a space created for that purpose—a structure to protect the passages and spaces—and thinks there is nothing inside.

Then are there any further unknown spaces? Kawae answers, "I don't think so," but adds, "Then again, I didn't think there was a Big Void either." The idea that there might be another passage on the north side had been around for some time. But what Kawae and his colleagues had expected was something beneath the large gabled structure. In reality, it was found behind it. That this space has a purpose is also suggested by the 3D survey work of Kawae's team. Even so, Kawae said he does not think there is anything more.

Kawae says he has been to the Great Pyramid more than 1,000 times. But when he first visited at age 19, his first impression was, "It's tiny." He felt, "Is this it?" and "There's nothing here," and on top of that, the vendors were relentless. A camel driver pressed him in odd Japanese with "Everything one dollar," and he got fed up.

Kawae became interested in Egypt because of a TV program he saw in middle or high school. Gilles Dormion of France and others had hypothesized that there was an unknown space inside the Great Pyramid and drilled holes beyond the horizontal passage. This became controversial. Sand came out of the holes, and no space was discovered. Later, Professor Yoshimura from Japan showed, through a survey using electromagnetic waves, that there might be a space, and Kawae found that fascinating. After failing his university entrance exams, he decided that what he wanted to study was Egypt and went there.

According to the narration, Kawae went on to live in Egypt for about 16 years. After working as a guide for four years, he received a scholarship to enter the American University in Cairo and began studying Egyptology in earnest.

As his knowledge deepened, the way he saw the pyramids changed. There is a view that one should experience a site's first impression without any prior knowledge. But Kawae says he is in the camp that believes you enjoy it overwhelmingly more if you go with knowledge. In the Valley of the Kings, the colors of the wall paintings survive and can amaze you, but the inside of the Great Pyramid has nothing. Even so, it contains the first royal sarcophagus made by hollowing out granite, and the first space in which an entire room was built of granite. When you consider that a single coffin took nine years, you can feel how remarkable it is. That is why the pyramid now feels truly enormous to him, Kawae says.

The narration also notes that humanity has not been captivated by the pyramids continuously for 4,500 years. Over the long centuries, the pyramids were forgotten, and there were periods when their stones were carried off as building material. Worldwide interest revived only in the last 200 years or so, as archaeology developed following Napoleon's expedition to Egypt.

So what is the Great Pyramid to people today? Kawae begins with the matter of time spans. People today tend to view things in short units—not even years, but months or days. But viewed on a grand scale, the concepts of the state, of administration and of taxation that were born 4,500 years ago are still in use today. Perhaps they will remain unchanged 4,500 years from now as well. On the other hand, some things have already been lost, such as building massive stone structures.

What has remained unchanged from ancient times to the present? When people look at the pyramids to find out, they tend to be captivated by the mystique or the size of the stones. But what Kawae says we should look at is what is "behind the screen"—the system of human activity behind it. That is something fundamental to human civilization, and it will probably still exist 4,500 years from now. By learning about it, we may be able to understand human beings, Kawae says.

The powerful centralized state that produced the Great Pyramid did not last forever either. "People really don't change," Kawae says. Bureaucrats gradually gain power, and bureaucrats who gain power become corrupt. There is no escaping that cycle. People often say we should learn from history, but the answer is already there. In the case of the pyramid age, the centralized system collapsed, partly under the influence of natural disasters, and from there something new emerged. Civilizations have repeated this cycle.

The question, Kawae says, is how we view it. Some will accept it as the fate of humankind, while others will believe it can develop into something different and try to create new systems. Others will come to think that power should not be concentrated. But because society is made up of many different people with many different ideas, it is not a simple matter, Kawae said in closing. The program ends by reflecting that even when the dynasty fell, the Great Pyramid remained, and leaves viewers with a question: is the rise and fall of civilizations—flourishing, declining, and giving birth to new societies—an inescapable fate for humanity?