The Great Pyramid at Giza: A Marvel of Ancient Egyptian Engineering

From the Lecture Series: The History of Ancient Egypt

By Bob Brier, PhD, Long Island University

Khufu­—also known by the Greek name of Cheops—built the Great Pyramid at Giza. Until the Eiffel Tower was built in 1889, it was the tallest building on Earth. Its base is so large it covers 13.5 acres; it’s made of 2.5 million blocks of stone, each averaging about 2.5 tons. It’s an incredible monument.

Image of the Sphinx and Pyramid of Khafre, Cairo, Egypt
(Image: Don Mammoser/Shutterstock)

But it is important to emphasize something right from the beginning. It wasn’t a high-tech monument, requiring masses of labor and skills of social organization, but it didn’t require higher mathematics. It was a tomb for the burial of a pharaoh.

Contrary to popular belief, the pyramids were not built by slaves. The Exodus, when the Israelites were in Egypt, was long after the pyramids were built. Hollywood has perpetuated the falsehood that while the pyramids were being built, slaves were whipped as they hauled enormous blocks of stone. There never was a large number of slaves in Egypt that were used for work projects.

This is a transcript from the video series History of Ancient Egypt. Watch it now, on The Great Courses Plus.

Head of Khufu in ivory displayed in Altes Museum. Old Empire, 5th Dynasty, around 2450 BC
Pharaoh Khufu (Image: By Marcus Cyron/Public domain)

We know for a fact that the Great Pyramid of Egypt was built by free labor. We have inscriptions left by the work gangs that worked on the pyramid that read, “Khufu’s gang did great work” and things like that. Egypt was mainly agrarian, with a majority of the population working as farmers. Each year when the Nile overflowed its banks, and when the land was inundated with water, the fields were underwater and farmers couldn’t do anything. This created a large workforce that Egypt could marshal to work on the pyramid, which may have been what happened.

The ancient Egyptians never wrote down how they built the pyramids. We have no papyrus at all that gives us a clue to how the pyramids were built. Remarkably, we have no architectural papyri at all, considering the many buildings the Egyptians constructed. They may have been seen as trade secrets among the architects that they didn’t want to reveal. There were other practices they didn’t write down. For example, Egyptians mummified people for thousands of years, but there was no papyrus telling us how to mummify a person. If we’re going to figure out how the pyramids were built, we have to study them and think about it.

Image of The Great Pyramid of Giza, Egypt.
The Great Pyramid of Giza is the tallest and the oldest pyramid in Giza, built by pharaoh Khufu. (Image: Photographed by Nina/Public domain)

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When you go on the Giza Plateau, two of the pyramids look very similar. It’s hard to tell which is the Great Pyramid. One was built by Khufu—that’s the one we call the Great Pyramid—and it’s also the taller one. But there is another pyramid that’s only 20 feet shorter built by a successor, Chephren, as he was called by the Greeks. The way you can tell them apart is the one that is not the Great Pyramid still has some of its white limestone casing at the very top. Most of the fine white limestone casing was pulled down in the Middle Ages to build the mosques of Cairo. It’s called Tura limestone and it came from the Tura quarries.

But how do you build a pyramid?

Image of the Pyramid of Khafre in Giza, Egypt
Pyramid of Khafre is the second tallest pyramid in Giza and in was built by pharaoh Chephren, the son of Khufu. (Image: Photographed by MusikAnimal/Public domain)

First, you don’t build a pyramid on sand, as it is unstable. It shifts; it moves. You clear down to bedrock and then level it down till it is perfectly level. How do you level an area of 13.5 acres? The prevailing theory is that the Egyptians dug channels around the base and then filled them with water; wherever the water would run out you would know that it was lower than the rest of the base. So you continued leveling until the water stayed in, then you knew you had a level base, like a carpenter.

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The pyramids are quite level. There have been careful surveys done of the Great Pyramid’s base recently, and surveyors have discovered it never varies by more than two inches over 13.5 acres.

How did they bring all the blocks to the site? First of all, the quarries were located near the pyramid, allowing for shorter transportation of the stone blocks. To this day, visitors can walk around the pyramid and see where the stones were pulled out. The very finest limestone for the casing, the smooth outer surface, came from farther away—floated across the Nile and then hauled into place.

If you go to the Great Pyramid, you will see there are two entrances. The pyramid’s entrance was covered over with white limestone and no one knew where the entrance was, even in ancient times. In the 9th century, the Caliph el-Mamoun—famous from The Thousand and One Nights—said that he wanted to rob the Great Pyramid but didn’t know where the entrance was. He had workmen chiseling away at the outside of the pyramid; they chiseled and chiseled, and discovered no entryway. Eventually, they built fires on the pyramid and doused it with cold water, cracking the stones.

Detail of the north side of the Cheops pyramid, located on the Giza plateau near Cairo, Egypt.
The 9th-century robbers’ entrance to the Great Pyramid. (Image: By Olaf Tausch/Public domain)

They kept removing more stones. As they were about to give up, one of the workmen heard a sound of a stone falling inside, so they knew they had hit a hollow chamber. According to The Thousand and One Nights, they went in and found only enough treasure to pay the workmen. It’s, of course, a story, but it’s probably true that around the 9th century they did indeed enter the Great Pyramid. The 9th-century robbers’ entrance is the one tourists go into today. The original entrance is higher up and sealed.

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The plan for the pyramid changed as it was constructed. Originally there was going to be a below-ground burial. There is still a large chamber beneath the ground, unfinished where you can see the crude bedrock. But Khufu’s burial was way above ground, high up in the pyramid. There is a remarkable passageway to get to the burial chamber called the Grand Gallery. It’s 28 feet high, narrow—maybe 10 feet wide—and has corbeled roofs. Nobody knows exactly why it was built. Some people believe that they stored blocks in the Grand Gallery that were then slid down to plug the entranceway.

Diagram of the interior structures of the Great Pyramid
A cross section of the Great Pyramid of Giza. (Image: By Jeff Dahl/Public domain)

After the Grand Gallery, you come to the burial chamber, a place filled with several puzzles. One, inside the burial chamber, is the stone sarcophagus of Khufu, the only thing ever found inside the burial chamber. It once had a lid that slid, which we can tell from the sarcophagus, but that’s all that’s there. No body was found, nor an inscription in the burial chamber.

Image of Sarcophagus in the King's Chamber inside Pyramid of Kheops, Giza
A sarcophagus in the King’s Chamber. (Image: By William Henry Goodyear, Joseph Hawkes, and John McKecknie/Public domain)

But the sarcophagus is about two inches wider than the doorway that leads to the burial chamber, and the sarcophagus is one piece of stone. That means they put the sarcophagus in the burial chamber before the pyramid was complete, probably in an attempt to prevent tomb robbers from dragging the sarcophagus out. Then they built the chamber around it.

The other interesting fact about the burial chamber is the ceiling. How do you build a roof that doesn’t crack with the weight of the pyramid above it? By corbeling—steps going inward to the top of the ceiling. When you go into this burial chamber there is no corbeling, just large slabs of granite going across the top. How come they don’t crack? It’s got the weight of the pyramid above it. Khufu had an interesting solution to the problem: relieving chambers.

Above the burial chamber, accessible through an outer hole, is a tiny relieving chamber. Only four feet high, it takes some of the pressure off the ceiling. Above that is another relieving chamber, and above that is another, a system structured all the way to the top. Above the relieving chambers are two huge blocks of stone forming an inverted triangle, which takes the pressure off the relieving chambers. All the force of the weight above the pyramid is distributed through the pyramid away from the ceiling. It’s a little bit like a corbeled step ceiling, only smoothed out into the form of an inverted “V.” The relieving chambers solve the problem of the weight on the burial chamber’s ceiling so it doesn’t collapse.

How do you get the stones—weighing three tons—all the way up to the top of the pyramid? It’s too steep to pull them up. There are two theories.

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One is the ramp theory: You build a long ramp and haul the stones up the ramp. Once you finish the pyramid you remove the ramp. Now, for something the size of the Great Pyramid, going 480 feet up in the air, the ramp would have to be more than a quarter of a mile long. The ramp would be a major engineering project. But we do know they used ramps because at Karnak Temple, against one of the walls is a mud-brick ramp that they used to get blocks up. Perhaps they used that technique.

The other possibility is what we call a switchback. When you go up a mountain road, your car is corkscrewing up the road; it doesn’t go straight up the mountain. They may have had the equivalent of a switchback road corkscrewing up around the pyramid until they get the blocks up and before they started filling it in. These are the two theories, but we don’t know which one is right.

The sides of the Great Pyramid are perfectly aligned on the four compass points: north, south, east, and west. Egyptians knew how to do that by careful observation of the stars and with the North Star. All of this required great workmanship. Some of the limestone casing blocks are still in place; they are so perfectly fitted, you cannot fit a piece of paper between them. It’s wonderful craftsmanship, especially on something that large. It was done within 22 years, the reign of Khufu, a remarkable achievement.

Common Questions About the Great Pyramid at Giza

Q: Are people allowed inside the Great Pyramid?

Yes. You are allowed inside all the pyramids and on most tours, entering the middle pyramid of the Queens of Cheops is free while the other two costs.

Q: Who was the builder of the Great Pyramid?

The Great Pyramid was built around 2551 BC by the pharaoh Khufu.

Q: How old is the Great Pyramid?

There is much disagreement on the precise age of all the pyramids and the dates keep changing with the refinement of dating procedures; however, the Great Pyramid and the rest at Giza are thought to have been built between 2589 and 2504 BC.

Q: How big are the blocks making up the Great Pyramid?

The blocks making up the Great Pyramids are massive and weigh around 2.5 tons each.

This article was updated on October 9, 2020

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