By Bob Brier, Ph.D., Long Island University
Uncovering the architectural secrets hidden behind the building of pyramids: the level base, the corbeled roofs, the relieving chambers, and the methods used for carrying heavy stones atop the pyramid.
First Step: Building a Level Base
How did the Egyptians build the pyramids? First, as we know, you can’t build a pyramid on the sand. Sand is unstable. It shifts; it moves. So they cleared it down to the bedrock, and then they leveled the bedrock. Now, how does one level an area of 13.5 acres? The Great Pyramid’s base is 13.5 acres. The prevailing theory is that they dug channels, and they filled them with water. Wherever the water would run out, one would know that it’s lower than the rest of the base.
There have been very careful surveys done recently of the Great Pyramid’s base. And it never varies by more than two inches over 13.5 acres. That’s precision. It’s great workmanship, but it’s not high tech. You don’t need higher mathematics to build a pyramid.
Learn more about the rise of the Old Kingdom.
Building the Structure of the Pyramids
Now that the foundations are leveled, how did they bring all those blocks to the site? First of all, they didn’t have to bring a lot of them to the site. The quarries were right around the pyramid. One can, to this day, walk around the pyramid and see the quarries.
So a lot of the stonework in the pyramid comes from right around it. The finest limestone for the casing, for that smooth outer surface, did come from farther away, it was floated across the Nile and then hauled into place.
This is a transcript from the video series History of Ancient Egypt. Watch it now, Wondrium.
The inside of the Great Pyramid is a marvel. There are really two entrances. One entrance is a ninth-century robbers’ entrance, which tourists use today. People don’t go into the original entrance. That’s higher up. That’s sealed off. The pyramid’s real entrance was covered over with the white limestone. Nobody knew where that entrance was in ancient times.
Khufu’s burial was above ground, way up in the pyramid. Now, how does one get that high up? There is a remarkable passageway to get to the burial chamber. It’s called the Grand Gallery. It’s a room that is still being debated as to what it was used for. It’s 28 feet high. It’s narrow. It has corbeled roofs.
It’s 10 feet wide and it goes all the way up the pyramid inside. Nobody knows exactly why it was built. Some people think they stored blocks in that Grand Gallery which were going to be slid down to seal the entranceway.
You go up this Grand Gallery, and then you come to the burial chamber. There are a couple of puzzles about the burial chamber. One, inside the burial chamber, is the sarcophagus, the stone sarcophagus of Khufu, the only thing ever found inside the burial chamber. And that’s all that’s there. Nobody was found, no inscription in the burial chamber. And this sarcophagus is about two inches wider than the doorway that leads to the burial chamber. It’s one piece of stone, the sarcophagus, but it’s two inches wider than the doorway.
Now, what that means is they put the sarcophagus in the burial chamber before the pyramid was complete. It was probably an attempt to avoid tomb-robbing, so the robbers couldn’t drag the sarcophagus out. They put it in, and then they built the chamber around it.
The other interesting thing about the burial chamber is the ceiling. Khufu’s father, Sneferu, had already solved the problem of the roof. How does one build a roof that doesn’t crack with the weight of the pyramid above it? By corbeling—steps going inward, inward, inward, all the way to the top of the ceiling.
But when you go into this burial chamber there is no corbeling. It’s big slabs of granite going across the top. Why don’t they crack? It’s got the whole weight of the pyramid above it. Khufu found an interesting solution to this problem. It’s relieving chambers.
If you can get above the burial chamber, there is a tiny chamber called a relieving chamber. It’s really small. You will have to crawl and crouch. It’s a chamber that’s about, maybe, four feet high, and that takes some of the pressure off the ceiling. Above that is another relieving chamber, and above that’s another relieving chamber. And all the way on the top, above the relieving chambers, are two huge blocks of stone forming a triangle, an inverted triangle, like a pyramid.
That takes the pressure off the relieving chambers, so all the force of the weight of the pyramid is distributed throughout the pyramid, away from the ceiling. It’s a little bit like a corbeled step ceiling, only smoothed out into the form of this inverted ‘V’, a triangle.
Learn more about ancient Egyptian thought.
Carrying Heavy Stones Atop the Pyramid
There are some very interesting questions about the Great Pyramid. How do you get the stones all the way up to the top? It’s too steep to pull up a stone weighing up to three tons? There are two theories.
One theory is the ramp theory: you build a long ramp and the stones are hauled up the ramp, and 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 perhaps they used that technique.
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. It goes around and around and around. That’s the technique they may have used for getting the blocks up to the top. 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. We don’t really know which one is the correct one.
But it didn’t take higher mathematics to do this, it took careful measurement. For example, another careful measurement was that the sides of the Great Pyramid were perfectly aligned on the four compass points: north, south, east, and west. Egyptians knew how to do that by carefully observing the stars. They could do that with the North Star, so one could do that.
This required great workmanship but not high-tech stuff. For example, some of the limestone casing blocks are still in place. You cannot fit a piece of paper between them, they are so perfectly fitted. That’s remarkable. It’s wonderful craftsmanship, especially on something that large. And think about it, all of it was done within 22 years, the reign of Khufu. A remarkable achievement.
Learn more about prehistoric Egypt.
Common Questions about How Did Egyptians Build the Pyramids
Pyramids were built with sheer manpower and gathering of tens of thousands of workers. Stones were supposedly pulled across the desert with ropes and sleds.
The Egyptians used different tools to build the pyramids including copper pickaxes and chisels, granite hammers, dolerite, and other hard stone tools.
We had to develop ideas and theories regarding the building of pyramids since the Egyptians purposely left no record of how they built their pyramids.
Herodotus was told by Egyptians that it took twenty years for a force of 90,000 oppressed slaves to build the pyramid, but now we know that these were free men of Egypt who built these Pyramids.