How the Egyptian pyramids were built has long been a mystery. Constructed as tombs for the pharaohs over 4,000 years ago, more than 100 of them remain. The largest one, the Great Pyramid of Giza, was originally 147m tall (482ft).
It’s made up of about 2.3 million stone blocks, each weighing between 2.5 and 15 tonnes, and would have had to be transported to the building site and lifted into place with techniques available at the time. To put this into context, it’s akin to lifting a double-decker London bus to the top of St Paul's Cathedral a few million times.
“There’s still debate between scientists on the exact method of raising these heavy blocks to such great heights,” says Dr Eman Ghoneim, a professor at the University of North Carolina Wilmington in the US.
Recent research is helping to fill in pieces of the puzzle, however. The most widely accepted theory is that ramps were used to haul the stones up, and it’s supported by remains of inclined structures found close to some of the pyramids. But the steepness of these ramps has been the subject of debate.
In 2018, Dr Roland Enmarch, a senior lecturer in Egyptology at the University of Liverpool and his team made a breakthrough by discovering a ramp cut into rock at a quarry at Hatnub, in the Eastern Desert of Egypt, which was an important source of alabaster used in the pyramids.
The angle of the ramp was more extreme than expected, with a slope of more than 20 per cent (previous estimates suggested that ramps in Ancient Egypt wouldn’t have exceeded 10 per cent). The team was studying inscriptions at the quarry that date back to the time the Great Pyramid was built, suggesting that a similar ramp could have been used in its construction.
“If you don’t have a very steep ramp, then you need a ramp of such enormous proportions to get to the top of the Great Pyramid that it would be a greater engineering feat than [building] the pyramid itself,” says Enmarch.
Construction timescales
Planning and building a pyramid would likely have been subject to time constraints as well. The average life expectancy in Ancient Egypt was 35 years and the construction of a pyramid typically started at the beginning of a king’s reign. The Great Pyramid of Giza is thought to have been completed in 20 years.
Frank Müller-Römer, an archaeologist at the Institute of Egyptology and Coptology in Munich, Germany, developed a theory of how the pyramids were erected that takes into account construction time, the tools and building methods available at the time, and engineering principles.
Different ramp designs have been proposed, such as a spiral shape around the outside, straight ramps running up each side or inclined pathways on the inside. However, Müller-Römer is convinced that several ramps, arranged along the outside of the structure, would have been used on all four sides.
“My theory offers a coherent solution for the construction of the pyramids in the shortest possible time,” he says.
Other techniques may have been involved as well, such as the use of levers, cranes and pulleys. In recent work published in PLoS ONE, Xavier Landreau from Paleotechnic, a privately owned research institute in Paris, France, and his colleagues proposed that a hydraulic lift system could have been used in the construction of the Step Pyramid of Djoser, the oldest of the pyramids.
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They investigated the terrain of a walled structure nearby and concluded that it was likely to be a small dam from which water would flow into trenches and then up shafts within the pyramid. A float system could then be used to raise stones through some of the shafts as the water levels changed.
Some experts doubt the theory is plausible though. Müller-Römer says that it contradicts previous archaeological evidence. Investigations at the Djoser pyramid suggest the structure was built in several stages, first as a mastaba – a flat-roofed, rectangular tomb structure – that was later expanded, layer-by-layer, into the first stepped pyramid.
Enmarch isn’t convinced either. He doesn’t think that such a hydraulic lift could raise stones to 60m (196ft), the height of the Djoser pyramid.
“Nothing in the paper suggested the Egyptians could apply pressurised hydraulics, which, in modern terms, would probably enable you to do that,” he says.
Modern scanning techniques are also being used to probe the internal structure of the Great Pyramid of Giza, which could lead to a better understanding of its construction.
Researchers from the ScanPyramids project, led by a team from Cairo University in Egypt and the Heritage Innovation Preservation (HIP) Institute in France, have been using non-invasive methods such as tracking particles called muons as they pass through the pyramids’ walls to search for hidden spaces inside.
In 2017, they discovered a huge cavity above the Grand Gallery, a narrow passage used to access the king’s burial chamber. Whether it had multiple purposes is still unclear, but it’s widely believed to have helped distribute the weight of the rock above the gallery.
Identifying supply lines
How workers and materials were transported to the sites has also been questioned. The Nile River was the main waterway used to carry goods at the time. But although studies have hinted at the presence of ancient branches of the Nile or canals close by, their exact location and size were unclear.
Ghonheim and her colleagues therefore decided to try and find them. They first captured satellite images, using radar waves that can penetrate the sand around the pyramids to reveal traces of buried rivers and ancient structures.
Using the technique, they uncovered a 64km-long (40-mile) ancient branch of the Nile. Segments of it border 31 pyramids, which suggests that they were active during pyramid construction.
The team then conducted surveys on the ground and collected and analysed soil samples that confirmed what they mapped from space.
“Our discovery provides insight into the method of transportation for the massive blocks used in the pyramids,” says Ghonheim.
“Over time, the Nile River shifted and branches disappeared because they silted up. There’s still an area in the upper and lower streams that needs to be mapped and this is what we’re after now,” she says. “We don’t have the complete picture yet.”
Another discovery that has shed further light on the construction of the pyramids is excerpts of records written by people involved in the construction work itself.
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Between 2011 and 2013, fragments of papyri from logbooks detailing the activities of workers at the Great Pyramid of Giza were found by Pierre Tallet, a professor of Egyptology at the University of Paris-Sorbonne, and his team at Wadi al-Jarf near the shores of the Red Sea.
Enmarch considers these documents to be the most important find of his 30-year career studying Ancient Egypt since they dispel more outlandish theories, such as aliens being involved.
“It shows it was a very large logistical undertaking, but just a building project nonetheless,” he says.
Rather than being mysterious, Enmarch considers the building of the pyramids to be an astounding feat achieved through the use of a large number of workers and the will to succeed. He thinks that ongoing excavations of workers’ settlements in front of the Great Pyramid of Giza will be key to learning new details about how the whole construction process was organised.
“In the last few decades, we’ve been getting an increasingly good idea of what must have been going on,” he says. “I’m sure [archaeologists] are going to carry on finding really fascinating stuff.”
About our experts
Dr Eman Ghoneim, a professor at the University of North Carolina Wilmington, has earned numerous academic and professional achievements in her field over the last 20 years. Her speciality lies in the use of Geographical Information Systems, utilizing hydrologic modelling in Flash flood hazards, Remote Sensing, Groundwater exploration in desert environments and present Sea Level Rise simulation.
Ghoneim has also become part of the editorial board of the Remote Sensing Journal and Journal of Geography, Environment and Earth Science International.
Dr Roland Enmarch is part of the University of Liverpool's Egyptology department as a senior lecturer. Beforehand, he originally graduated with a Bachelor's Degree from Oxford in Oriental Studies, specifically Ancient Egyptian with Akkadian. Ahead of arriving in Liverpool in 2004, he even earned a PhD in Egyptian pessimistic poetry.
Frank Müller-Römer, is a German archaeologist & egyptologist, studying and earning a PHD the Institute for Egyptology and Coptology at the Ludwig Maximilian University of Munich. Ever since, he has been part of numerous lectures, TV programmes, and publications, including those based on Construction and Transport Techniques in Ancient Egypt.
He was also part of the Collegium Aegyptium – Support Group of the Institute of Egyptology at the Ludwig Maximilian University of Munich, as chairman of the board, from 2003 to 2015.
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