Hey there, curious minds! A while back, we explored the amazing pyramids of Egypt and how they were built using science, not aliens. Many of you wanted to know more about how these incredible structures were actually constructed, so let’s dive into that!
There are over a hundred pyramids in Egypt, but let’s focus on the most famous one: the Great Pyramid of Giza. This massive structure was originally over 146 meters tall and made up of about 2.3 million stone blocks. The foundation of the pyramid is incredibly precise, with its base level to less than 2 centimeters, and its sides aligned almost perfectly to the compass, even though compasses didn’t exist back then!
Finding North was simpler than you might think. By watching where a star rises and sets at night and cutting the angle in half, the Egyptians could find North. To make sure the pyramid’s sides were square, they used a 3-4-5 triangle, which forms a perfect right angle. They might have used water-filled channels to level the base, but it’s more likely they used their knowledge of right angles to create a level surface.
The core of the Great Pyramid is made from over 2 million blocks of limestone, which were quarried right next to the pyramid site. This was convenient because the limestone was deposited there by ancient oceans. The Egyptians dug channels and pried the blocks from the Earth, using the natural layers of limestone to determine the size of each block.
The outer layer of the pyramid was originally covered in smooth white limestone, which was later used for other buildings. The Egyptians used copper tools, along with sand and powdered rock, to cut the limestone. Even though copper is a soft metal, it was effective for this purpose.
To build the Great Pyramid in 23 years, a huge amount of stone had to be quarried and moved. Modern experiments show that a team of 1,200 to 1,500 workers could handle this task. The Egyptians used large boats to transport stones down the Nile River. For moving the stones on land, they used wooden sleds. By wetting the sand, they reduced friction, making it easier to pull the sleds.
Constructing ramps to move the stones up the pyramid was a big challenge. Although we don’t have exact records of what these ramps looked like, researchers have some ideas. They think the Egyptians used a wide ramp at the bottom and spiral ramps near the top. Wooden levers and round stones helped guide the blocks into place. The outer stones were fitted so precisely that you can’t even slip a credit card between them!
It’s a myth that the pyramids were built by slaves. In reality, skilled workers lived in nearby cities, complete with breweries, bakeries, and tool shops. These workers were proud of their role in building the pyramids, which were considered the kingdom’s greatest achievement.
It’s amazing how much we’ve learned about how the pyramids were built, but it wasn’t easy. It took a lot of hard work and ingenuity. Remember, just because something is difficult doesn’t mean it’s impossible. Stay curious and keep exploring!
Using clay or building blocks, try to create a small-scale model of the Great Pyramid. Pay attention to the pyramid’s base and how it aligns with the cardinal directions. This will help you understand the precision and engineering skills of the ancient Egyptians.
Use a piece of string to create a 3-4-5 triangle. This will form a perfect right angle. Try using this method to draw a right angle on paper or on the ground, just like the Egyptians did when they built the pyramid’s base.
Gather some friends and use a sled or a piece of cardboard to move a heavy object across a sandy surface. Wet the sand and observe how it reduces friction, making it easier to move the object. This activity will give you insight into how the Egyptians transported heavy stones.
Choose one aspect of the pyramid’s construction, such as the ramps or the workers’ village, and research it further. Create a short presentation or poster to share your findings with the class. This will help you dive deeper into the topic and improve your research skills.
On a clear night, observe the stars and try to identify the North Star. Use this to understand how the Egyptians might have found North. Discuss with your classmates how ancient civilizations used the stars for navigation and construction.
This episode is supported by Skillshare. Hey smart people! A few weeks ago, we made a video about the pyramids and how, while they are quite impressive, we can trace the evolution of their construction. The ancient Egyptians used trial and error and made a few mistakes, which suggests they didn’t need aliens to build them; they just needed science. You all really liked that video, but some of you were a bit bothered that, despite it being titled “WHO built the pyramids?”, I didn’t discuss HOW the pyramids were made. So, let’s talk about it!
The hundred-plus pyramids scattered around Egypt were built a bit differently, but we’re going to focus on THE BIG ONE. Let’s review the stats! The Great Pyramid originally rose more than 146 meters tall and contained about 2.3 million stone blocks. The start of any construction project truly begins with the foundation, which is impressive in its own right. Its base is level to less than 2 cm, square to within 11 cm, and its edges are aligned to the compass within 3/60ths of a degree. This precision is remarkable, especially considering that compasses didn’t exist yet, and the North Star was in a different position 4,500 years ago.
Finding North is actually pretty easy; just observe where any star rises and sets during the night and cut the angle in half. After that, squaring the sides just requires measuring a right angle. Ancient cultures, including the Egyptians, understood that a 3-4-5 triangle creates a 90˚ corner. They could even create a right angle using two circles: the line connecting the intersection of the arcs is perpendicular to a line through their centers.
To level the base, some theories suggest the Egyptians used water-filled channels as natural levels, but this seems unlikely considering how much water they’d need to transport to prevent evaporation. However, if you can create a right angle, you can achieve a level surface. With that foundation, you can level over long distances. When you think about it, a pyramid is just a series of stacked squares, so mastering this measurement is crucial.
Now, we just need some stones. The Great Pyramid’s core is made of more than 2 million blocks of rough yellow limestone, quarried right next to the pyramids. This is a significant reason why they chose sites like Giza, where prehistoric oceans had deposited this building material right beneath their feet. They would dig channels and pry these blocks from the Earth, with the size of the blocks determined by the natural thickness of the limestone layers.
Evidence of these layers can be seen in The Sphinx, which was actually dug out of the Earth rather than built on top of it. The pyramids were originally covered in smooth white limestone from quarries up the Nile, which was repurposed for other buildings thousands of years ago. Numerous chisels, drills, and saws have been found at these quarries, and the only metal the Egyptians had access to was copper. While copper is a soft metal, when combined with a slurry of sand and powdered rock as an abrasive, it can effectively cut limestone.
To build the Great Pyramid in 23 years, an Olympic swimming pool’s worth of stone had to be quarried every eight days. This is a significant amount, but modern experiments using technology available to the ancient Egyptians suggest that a quarry team of 1,200 to 1,500 workers could manage this task. Heavier stones, like the granite used in the pyramid’s inner chambers, are much harder than limestone. They were chipped out by hand using heavy dolerite hammer stones, which have also been found in abundance. It would have taken a full day’s work to chip away just a few centimeters, but they didn’t have modern distractions.
We’ve discovered Egyptian boats large enough to transport these stones down the Nile, but how were 2 million blocks actually moved into place? Surprisingly, wheels for transportation are a relatively recent invention, not because rolling a round object is difficult, but because creating a workable axle is. The oldest known rolling wheels date back to before the Great Pyramid, but not in Egypt. Paintings indicate that Egyptians used wooden sleds to move large objects, but they still had to contend with friction.
Burying wooden rails horizontally allows a sled to slide more freely, and research has shown that wetting sand with the right amount of water makes it remarkably slick. A team of ten workers can easily pull a one-ton sled, but it’s important to remember that Egyptians also had animals like donkeys and cattle to assist.
Constructing ramps to deliver stone must have been nearly as monumental as the pyramid itself. There are no records of what these ramps looked like, but researchers have examined various possibilities. An engineer named Craig Smith has conducted detailed ramp analyses, calculating how many stones could be delivered with each design. He believes the Egyptians extended a wide ramp near the bottom, where most stones were needed, and used spiral ramps near the top, where fewer blocks were required.
Wooden levers and round dolerite “ball bearings” were used to guide stones into place, where they were carved to fit precisely. The joints between some of the remaining smooth outer stones are so precise that you can’t even slip a credit card between them, but excavations have shown they were less careful with interior stones.
It’s a common misconception that the pyramids were built by slaves, but that’s largely a myth perpetuated by movies. Egyptologists have uncovered large cities built to feed, house, and equip thousands of skilled workers, complete with breweries, bakeries, and tool shops, indicating that whole families lived nearby. Egyptian society at all levels dedicated themselves to what they viewed as the kingdom’s proudest work.
It’s quite incredible that we have as much evidence as we do about how the pyramids were built, but that doesn’t mean it was easy. In fact, it was quite the opposite. But difficult doesn’t mean impossible. Stay curious!
Pyramid – A large, triangular structure with a square base, often used as a tomb or monument, especially in ancient Egypt. – The ancient Egyptians built the Great Pyramid of Giza using precise engineering techniques.
Engineering – The application of scientific and mathematical principles to design and build structures, machines, and systems. – Engineering students learn how to design bridges that can withstand strong winds and heavy traffic.
Limestone – A sedimentary rock composed mainly of calcium carbonate, often used in building materials. – The outer casing of the Great Pyramid was originally made of smooth, white limestone.
Workers – People who perform tasks, especially in construction or manufacturing, to build or create something. – Thousands of workers were involved in the construction of the ancient pyramids.
Tools – Devices or implements used to carry out a particular function, especially in construction or engineering. – The workers used simple tools like chisels and hammers to shape the stones for the pyramid.
Ramps – Inclined surfaces used to move objects to a higher or lower level, often used in construction. – Engineers believe that ramps were used to transport heavy stones to the top of the pyramid.
Stones – Solid mineral materials used in construction, often cut or shaped for building purposes. – The massive stones used in the pyramid’s construction were transported from quarries miles away.
North – A cardinal direction, opposite to south, often used in navigation and orientation. – The Great Pyramid is precisely aligned with the cardinal points, with its sides facing north, south, east, and west.
Angles – The space between two intersecting lines or surfaces, measured in degrees. – Engineers calculated the angles of the pyramid’s sides to ensure its stability and symmetry.
Construction – The process of building or assembling infrastructure or structures. – The construction of the pyramid required careful planning and coordination of resources.
