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

From a lecture series presented by Professor Bob Brier, Ph.D.

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, incredible monument.

Cheops Pyramid

But it is important to emphasize something right from the beginning. It wasn’t a high-tech monument. It required masses of labor and skills of social organization—getting people together to build it—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. When you watch movies where you see the pyramids being built, and the slaves are hauling on the blocks with one guy whipping them along—that’s Hollywood. There never was a large number of slaves in Egypt that were used for work projects. Never.

We know for a fact that the Great Pyramid of Egypt was built by free labor. We have inscriptions by the work gangs that worked on the pyramid that say, “Khufu’s gang did great work” and things like that. Egypt was mainly agrarian, practically everybody was a farmer. The Nile overflowed its banks each year, and when the land was inundated with water, the fields were under water and farmers couldn’t do anything. So there was a large work force 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. In fact, we have no architectural papyri at all, which is remarkable when you think about all the buildings the Egyptians made. They may have been seen as trade secret among the architects that they didn’t want to reveal. There were other things 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. So if we’re going to figure out how the pyramid was built, we have to sort of just look at it and think.

Learn More: Mummification—How we Know What We Know

When you go on the Giza Plateau, there are two pyramids that 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 that’s the taller one. But there is another pyramid that’s only 20 feet shorter built by a successor, Chephren, as he’s 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.

Now, how do you build a pyramid? First, you don’t build a pyramid on sand. Sand 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 they 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 kept leveling until the water stayed in, then you knew you had a level base, like a carpenter.

Learn More: Sneferu, the Pyramid Builder

It’s very level, by the way. There have been careful surveys done of the Great Pyramid’s base recently, and it never varies by more than two inches over 13.5 acres. That’s precision.

How did they bring all the blocks to the site? First of all, the quarries were right around the pyramid. To this day you can walk around the pyramid and see where the stones were pulled out. A lot of the stonework in the pyramid comes from right around it. That way you didn’t have to transport so many blocks. The very finest limestone for the casing, the smooth outer surface, came from farther away. It was 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 the white limestone and nobody knew where the entrance was, even in ancient times. In the 9th century, the Caliph el-Mamoun—we read about him in 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 nothing happened. Eventually they built fires on the pyramid and doused it with cold water, cracking the stones.

They kept removing more stones, and they were about to give up when one of the workmen heard a sound of a stone falling inside, so they knew they had hit a hollow chamber. And, 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.

Learn More: The Great Pyramid of Giza

The plan for the pyramid changed as it was being built. Originally there was going to be a below-ground burial. There is still a big 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 think that they stored blocks in the Grand Gallery that were slid down to plug the entranceway.

Great Pyramid Diagram
Great Pyramid Diagram

After the Grand Gallery you come to the burial chamber. There are several puzzles about the burial chamber. 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, no inscription in the burial chamber.

Image of Sarcophagus in the King's Chamber
Sarcophagus in the King’s Chamber

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 thing 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 all the way to the top of the ceiling. When you go into this burial chamber there is no corbeling. It’s big slabs of granite going across the top. How come they don’t crack? It’s got the weight of the pyramid above it. Well, Khufu had an interesting solution to the problem: relieving chambers.

If you crawl in through a hole outside to get above the burial chamber, there is a tiny relieving chamber. It’s maybe four feet high, but it takes some of the pressure off the

Image of Corbelled chamber with hieroglyphs in Hattusa
Corbelled chamber with hieroglyphs in Hattusa

ceiling. Above that is another relieving chamber, and above that’s another. 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. So 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 ceiling of the burial chamber so it doesn’t collapse.

How do you get the stones—maybe 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.

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. So maybe they used that technique.

Image of Switchbacks on the Route du Col de Braus (France)
Switchbacks on the Route du Col de Braus (France)

The other possibility is what we call a switchback. It’s how, 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 you get the blocks up and then you start filling 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, and you cannot fit a piece of paper between them, they are so perfectly fitted. It’s wonderful craftsmanship, especially on something that large. And it was done within 22 years, the reign of Khufu. A remarkable achievement.

Keep reading:
The Mask of Tutankhamen
Egypt and the Gift of the Nile
Ancient Astronomy—From Stonehenge to the Great Pyramids
Who was Napoleon Bonaparte? The Early Years

From the Lecture Series: The History of Ancient Egypt
Taught by Professor Bob Brier, Ph.D.

 

The Great Pyramid, Nina at the Norwegian bokmål language Wikipedia [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) or CC BY 2.5 (http://creativecommons.org/licenses/by/2.5)], via Wikimedia Commons
Great Pyramid Diagram, By Jeff Dahl (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 4.0-3.0-2.5-2.0-1.0 (https://creativecommons.org/licenses/by-sa/4.0-3.0-2.5-2.0-1.0)], via Wikimedia Commons
Sarcophagus in King’s Chamber, By William Henry Goodyear, Joseph Hawkes, and John McKecknie – Brooklyn Museum, No restrictions, https://commons.wikimedia.org/w/index.php?curid=31447892
Corralled Chamber, By Elelicht (Own work) [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Common
Col de Braus, Ericd [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], via Wikimedia Commons
All Gizah Pyramids, By Ricardo Liberato (All Gizah Pyramids) [CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons