PYRAMIDS OF GIZA -- wonder of the world

The Great Pyramid of Giza is the largest pyramid in Egypt and the second largest ever constructed. It was built for Khufu (Cheops), the fourth dynasty Pharoah of the Egyptian Old Kingdom. Built of solid stone, originally clad in polished white limestone, Khufu's pyramid would have dazzled viewers with reflected sunlight. Its impressive exterior conceals chambers and shafts, and an empty sarcophagus, hinting at the possible treasures lost in antiquity.

They are a symbol of the humans’ desire to unravel the mysteries of the ancient Egyptian civilisation. And these days, they also show how modern life is catching up to these ancient symbols. Slowly, Cairo’s satellite cities are creeping ever-closer to the pyramids. Scientists even believe that each of the pyramids once had their own temple, most of which will now be buried under these towns. One of the only temple still visible is that of Cheops (Khufu) near the Great Pyramid of Giza.

The many treasures found here give a clear indication of a highly civilised culture, which formed around 3300 BC and disappeared around 332 BC. That’s when Alexander the Great conquered Egypt. Remarkable is that he left much of this culture intact, so parts of it have remained for centuries.

The huge blocks used to build the Great Pyramid were transported in an ingenious way, by around 20.000 people. It is estimated it took around 20 years to build the huge crypt. The pyramid is almost 230 metres wide and 147 metres high, making it the largest in the world.

It’s understandable that tourists and scientists alike are interested in these large structures. The complex includes much more than just the pyramids. Giza is also home to other tombs of less important people, and channels dug by hand so ships could moor here. Those were to ensure a king’s funerary proceedings would run smoothly.

There are two smaller pyramids near the Great Pyramid: that of the pharaohs Chephren (Khafre) and Menkaure. These are actually pyramid complexes in their own right, just on a smaller scale. Each building served an important purpose, though it’s still not clear exactly which.

More than 100 pyramids are known to have been constructed in Egypt but only seven of those completed used dressed stone throughout, such as can be seen at the Great Pyramid. Most were of mud brick clad in limestone. Few have survived. Their purpose is believed to be both tomb and temple.

Khufu's pyramid is the earliest and largest of those on the Giza plateau. It is aligned almost perfectly north-south and visible from modern-day Cairo. Giza lies west of the River Nile, in the region known as Lower Egypt, and across the river from the ancient cities of Heliopolis and Memphis, once the capital.

The Great Pyramid is also one of the seven wonders of the ancient world — the only one on the list still in existence. The others are the Colossus of Rhodes, the Statue of Zeus at Olympia, the Mausoleum at Halicarnassus, the Hanging Gardens of Babylon, the Temple of Artemis at Ephesus and the Pharos of Alexandria. The Great Pyramid was the world’s tallest building for more than three and half thousand years, until the spire of Britain's Lincoln Cathedral was completed in 1311.

The name Khufu has been found amongst quarry marks (red painted symbols) on blocks of stone inside the pyramid. He is thought to have ruled for 23 years, 2589-2566 BC, as second pharaoh of the 4th dynasty. The span of his reign is recorded variously in hieroglyphic texts as 23, 46 or 63 years but the Royal Canon of Turin papyrus, dating from the 19th dynasty, indicates 23 years.

Modern Egyptologists agree that constructing the pyramid is likely to have taken some 20 to 23 years. Traditionally held to have been a mausoleum for the pharaoh’s body, it has also been suggested that his mortal remains were interred elsewhere and the pyramid functioned as a sacred monument.

Khufu's vizier, Hemienu, architect and overseer of construction projects, is likely to have been the pyramid's designer. The position of vizier was the highest office below pharoah in ancient Egypt, and Hemienu was related to Khufu — probably his half-brother or half nephew. His own tomb is a mastaba (flat-topped mud structure, usually rectangular) close by.

The Great Pyramid is accompanied by two other major, though smaller, pyramids at Giza, and these belong to Khufu's descendants — Khafre (son) and Menkaure (probably grandson, perhaps son), also of the fourth dynasty. The Great Sphinx is also part of the pyramid complex.

Physical description

In its completed form, the Great Pyramid was 146.6m high. It is square in plan, and the length of each side at the base was 230.4m. The walls slope at 51.5 degrees, and the pyramid occupied a volume of 2.6 millon cu m.

The monument was surrounded by a low wall and a number of associated structures — a complex of buildings, a mortuary temple adjacent to the east side with a causeway to a valley temple at a harbour, three smaller pyramids, four pits containing buried disassembled boats, and numerous rectangular mastabas to the east, south and west.

The Great Pyramid is founded on a natural rock outcrop, which helped reduced the amount of stonework needed but also prevented the cross-checking of the set-out of the plan, as the diagonals could not be measured. Even so, the base layer of fine white limestone, on which the whole pyramid rests and which skims the central outcrop, is a perfect square. Although the outcrop slopes, the top of the huge stonework platform is level to within 21mm across its width. It's unclear how this was achieved.

The main body of the pyramid is constructed on the platform, its internal layout presumably built as the pyramid grew. To construct it, rectangular blocks were cut from the local limestone at Giza, and laid in stepped courses. For the cladding and the lining of internal passages, better quality fine-grained limestone from near Tura and Masara, on the east side of the Nile, was used. On the exterior, the facing averaged 1.3m in thickness and was cut to the slope and polished. The facing blocks were so well fitted together that their mortared joints were said to be barely visible.

Unlike other pyramids, the Great Pyramid appears never to have had a capping stone at its apex. The top is unadorned and the masonry exposed.

The entrance to the monument is on the northern face, 17m above the base and 7.3m east of the centreline. It is surrounded by some of the largest stones in the entire structure, including a pointed arch formed by two courses of inclined blocks. No door survives and it has been suggested that a swivelling block was used, originally hidden behind the facing stones.

Greek geographer Strabo (c64 BC-c23 AD) records an (undiscovered) entrance on the south side as having "a movable stone, and when raised up there is a sloping passage to the vault".

From the entrance, a passage 1.1m wide and 1.2m high descends at an angle of 26.5 degrees (about 1 in 2) through the masonry and bedrock for 105m. It then follows a level course for 8.8m and opens into an unfinished subterranean chamber. If completed, this chamber would have been 14m long, 7.3m wide and around 5.3m high. A cramped horizontal corridor 790mm high and 740mm wide extends 16m into the bedrock at the south end of the room opposite the doorway, but as with the chamber, its purpose is unknown.

Some 28m from the entrance the descending passage branches into another passage of similar dimensions, this one ascending at 26.1 degrees and running for 38m. The opening to it, set in the roof of the descending passage, is sealed tightly with three red granite plugs, which may have been slid into place or erected in situ. The lower part of the ascending passage appears to have been cut through pre-existing masonry work, perhaps signalling a design change. The blocks of the passage walls are laid in line with the slope, and at three separate locations vertical girdle stones (rectangular rings) wrap the corridor.

The second half of the ascending passage becomes the Grand Gallery, a vaulted space with seven levels of roof corbelling, which continues ascending at a similar gradient. The gallery is 2.1m wide for a height of 2.3m, after which the walls step inwards approximately 75mm on each side for each corbel. It is 46.9m long and a maximum of 8.8m high, and of higher quality limestone than the surrounding core stones. The third layer of corbelling is incised with a groove, approximately 25mm deep and 180mm high, along the full length of the gallery. Its purpose is unclear but it has been suggested that it could have supported a false ceiling.

At the start of the Grand Gallery, a horizontal passage 38.7m long, 1m wide and generally 1.2m high with a step down to 1.7m high, leads to an apartment usually (erroneously) referred to as the Queen’s Chamber. This could have been a serdab, a hallowed place (usually sealed) containing a statue of the relevant dead pharaoh.

The chamber is 5.8m long and 5.3m wide with a corbelled niche, 4.7m high and 1m deep, at the east end, and a gabled roof rising to a centre height of 6.2m. It is constructed in dressed limestone and was evidently important — perhaps the most significant room in the whole structure — as it’s located at the plan centre of the pyramid and was hidden behind sealed doors. Two small inclined shafts about 200mm square exit the chamber, and were also concealed.

The upper end of the Grand Gallery steps up and opens into an antechamber, originally sealed by a portcullis system that inlcuded three granite slabs. Each would have been 530mm thick and at least 1.2m square (probably larger). The only traces of the original mechanism are four slots cut into the walls. Remnants of what appear to be portcullis slabs, with drilled holes some 90mm in diameter, have been found at various locations in the pyramid.

The antechamber leads to the King’s Chamber, where the pharaoh may have been laid to rest. If so, that would make it the only example of an ancient Egyptian burial chamber at a higher elevation than its tomb entrance. The chamber is about 90m below the pyramid’s apex, and is 10.5m long, 5.2m wide and 5.8m high. Its walls are plain and its ceiling of smooth polished granite is flat. Some of the nine ceiling stones are more than 5.5m long and weigh over 25 tonnes. It also has two small inclined shafts some 200mm square leading away from the chamber.

A roughly finished sarcophagus 2.3m long, 1m wide and 1m high, weighing about 3.8 tonnes, made from a single block of red granite is positioned at the west end of the chamber, on the central axis of the pyramid. Its sliding lid is missing and one corner has been broken.

Above the King’s Chamber, and not discovered until the 18th and 19th centuries, is an intricate ladder of shallow chambers, all of granite roughly worked on the upper faces but smooth on the bases and sides, topped by a gabled roof of granite slabs. Thought at first to be 'relieving' chambers designed to distribute the massive loads, or perhaps 'chambers of construction' to protect the King’s Chamber from earthquakes, opinions differ about their true purpose. It’s possible that the arrangement mimics the djedt, a representation of the god Osiris (specifically his spine). Osiris is the god associated with death, resurrection and the afterlife, making the djedt a symbol of supreme religious significance for the ancient Egyptians.

The King’s Chamber and the chambers and gabled roof above it are the only structures inside the Great Pyramid to be constructed in granite, which was brought from Aswan 800km away in southern Egypt. Perhaps significantly, higher radiation levels have been recorded in the chambers than in the surrounding desert.

Construction methods and theories

Fourth dynasty Egyptian craftsmen are know to have used a range of tools at Giza, including hand-held stone hammers, knives and bladed implements with wood or bone handles, wooden drills with flint or copper bits, chisels of flint or copper, band saws operated by one or two people, and tubular saws for extracting cores. The copper for the drill bits was hardened by the addition of up to 7 percent arsenic during smelting, followed by repeated annealing and toughening by hammering. Wet quartz sand was used as an added abrasive on the saw blades.

No records exist concerning the actual method of construction used for the Great Pyramid, or any specialised equipment developed to build such an immense structure. This has led to all manner of theories. The wheel was unknown at the time, and it is assumed that heavy weights were moved on sledges on rollers.

Some clues may found in the works of ancient Greek historians. Herodotus (c484-c425 BC), writing around 450 BC, claims that the pyramid was constructed in 20 years by a workforce of about 100,000 slaves. Four centuries later, Diodorus Siculus notes in his Bibliotheca historica (60-30 BC), "It is said that the stone was brought over a great distance, from Arabia, and that the construction was undertaken with the help of ramps, since at that time cranes had not yet been invented".

Consensus among archaeologists suggests that a workforce of 20,000 to 25,000 people would have been required, probably consisting of around 5,000 salaried employees living in a purpose-built town with their families, and up to 20,000 temporary staff working short-term contracts and living in a camp near that town. Construction was carried out by at least 4,000 primary labourers such as masons, quarrymen and hauliers, with some 16,000 to 20,000 secondary workers building ramps, mixing mortar, making tools and bringing in supplies.

In modern trials carried out under the direction of archaeologist Dr Mark Lehner, President of the Ancient Egypt Research Associates (AERA, founded 1986), and stonemason Roger Hopkins, 12 quarry workers produced 186 blocks in 22 working days.

It's thought that the workers were not slaves but conscripts and volunteers — members of a structured society. The project's scale likely meant it involved people from all over Egypt and was a source of national pride. South-east of the pyramids, a large complex of buildings has been discovered, designed for materials storage, bread baking, fish and meat processing, beer brewing, copper working and the making of funerary artefacts. The itinerant workers slept in barracks-style dormitories. Most of the accommodation for salaried staff is thought to lie beneath the present day settlement of Nazlet el-Samman.

Most scholars agree that for pyramid building, materials were brought to site and placed using ramps. The type and configuration of the ramps is open to conjecture. Internal, external, perpendicular, zig-zag and winding ramps have all been proposed. At Giza, excavation has uncovered two parallel walls that may have formed the retaining framework of an external ramp.

French Egyptologist Jean-Philippe Lauer (1902-2001) believed lifting devices including levers, round beams, poles and ropes were used to manoeuvre stone blocks up a ramp system of various sizes and gradients. He envisaged four large linear ramps, each running vertically up one side of the pyramid, with another ramp running to the stone quarry south-east of the site. Smaller ramps built into the core of the pyramid were used to move the heaviest blocks, counterweighted by sacks of sand. Lehner suggests the quarry ramp was spiral rather than linear.

Continuing the spiral theme, French architect Jean-Pierre Houdin (b.1951) asserts that the top two thirds of the pyramid was built up around an internal square spiral ramp, which became part of the finished structure. An external ramp was used to construct the lower third, and the stone recycled into the upper portion. Houdin explained the cracks in two of the granite slabs in the King's Chamber as having occurred during construction and been plastered over by Hemienu to act as tell-tales.

Most speculation on the stone transportation involves the hewn blocks being pulled on sledges by teams of men or possibly oxen, using a procession of round log rollers laid in front of the sledges as they progress. Friction is reduced by pouring water, or perhaps watered oil, onto the rollers and sledge runners.

In 1991, construction enthusiast Franz Löhner suggested that the stone blocks could be hauled up the growing pyramid with hemp cables slung round a timber 'rope roll' (a rotating spindle set between two blocks). The technique uses the combined power of the labourers’ strength and their weight, so requires fewer people. Löhner estimated a team of 48 men could haul a block up the steep incline, whereas more than 50 would be needed to pull a block on rollers along an almost flat slope.

In 2014, Ben Hendriks suggested that the blocks could have been cradled inside slatted drums and rolled along. He also envisaged zig zag ramps cutting into one side of the pyramid and timber scaffolding platforms near the top for access. The ramps would be infilled from the top down once the pyramid had reached full height. His theory requires some kind of lifting device for the heavier blocks.

French materials scientist Joseph Davidovits (b.1935) put forward a startling theory in 1974. He argued that the pyramid’s blocks were cast in situ using a type of 'concrete' and that the casing stones were man-made too. Large-scale batch mixing would have been necessary for this and so far no traces have been found. Sample stone analysis done circa 2006 does not appear to support the theory either.

Archaeological investigations

Since Khufu's time, robbers, explorers and archaeologists have made numerous forays into the interior of his pyramid. We have no idea whether it contained golden artefacts, records of contemporary literature and science, or even a mummy. We may never know.

Around 820 AD, Abdallah al-Mamun (786-833), seventh Abbasid Caliph of Baghdad, employed workers to tunnel into the north side of the Great Pyramid, ten stone courses below the original entrance. The almost horizontal tunnel runs for some 27m, ending in the descending passage, where three slabs block the start of the ascending passage. It bypasses the stones, entering the passage beyond and reaching the King’s Chamber.

In 1765, Nathanael Davidson (c.1736-1809) found a space (now called Davidson’s Chamber) above the King’s Chamber by following an echo from the Grand Gallery. A rectangular passageway, about 600mm wide, at the top of the gallery led him 7.6m to a chamber around 900mm high. Its floor consisted of the rough-hewn tops of the nine granite slabs forming the ceiling of the King’s Chamber.

When Napoleon Bonaparte (1769-1821) and his military force made their expedition to Egypt in 1798-9, they were accompanied by 175 French civilian scientists. They surveyed the pyramid trigonometrically and discovered two of the corner sockets at its base, thought to be unique to the Great Pyramid. They also uncovered the Rosetta Stone, which enabled the deciphering of hieroglyphs.

In 1816-7, Giovanni Battista Caviglia (1770-1845) excavated the descending passage, discovering a connecting well shaft between it and the lower end of the Grand Gallery. It seems to have been constructed contemporaneously with the pyramid, and has two vertical sections and three inclined sections, with a 'grotto' chamber in the bedrock opening into the lower vertical shaft. Caviglia also found the unfinished subterranean chamber at the foot of the descendary, and deepened the existing pit in its floor by 9m.

In 1836-7, Richard William Howard Vyse (1784-1853) uncovered in situ casing stones on the north side below the entrance. He used gunpowder to blast a hole in the south side, some 9m long and starting about 18 courses above the base. He uncovered four cavities above Davidson’s Chamber, which he named Wellington’s, Nelson’s, Lady Arbuthnot’s and Campbell’s chambers. Some of the stones framing the chambers were marked with red paint, and included cartouches containing the names Khufu and Khnum-Khufu — the only references to the pharaoh in the pyramid. Debate on the authenticity of the inscriptions continues, though it’s likely they were made by the pyramid workers’ gangs.

In 1872, engineer Waynman Dixon (1844-1930) revealed the two narrow shafts angling upwards from the Queen’s Chamber by tunnelling horizontally from inside the chamber. In the northern shaft he found a 540g ball of diorite or granite and a 50mm long double hook of copper or bronze riveted for fixing to a wooden handle, both of unknown function, and a 130mm long fragment of cedar thought to be part of a measuring rod.

Surveys by Petrie in 1880-2 showed that the Great Pyramid had more than 200 courses, 1.5m thick at the base and 0.5m deep at the top. They were laid in layers with step widths between courses ranging in width from 0.4m to 1.4m, or an average of 0.6m. Traditionally the structure was believed to contain some 2.3 million blocks weighing from around 2.5 tonnes to 15 tonnes each.

Conversely, modern analysis suggests the pyramid has far fewer large blocks than earlier surveys supposed. Most of the casing stones were removed in the Middle Ages, revealing a series of steps — in rality backing stones placed to fill the space between the pyramid’s core and its casing. The steps are irregular and become progressively smaller towards the top.

Beneath the backing stones, the masonry core is even more irregular, with a change in size of blocks at the 35th course. Examination of Howard Vyse’s opening reveals a core of huge uneven rectangular blocks, separated by gaps as wide as 220mm, which have been filled with blobs of mortar, stone rubble and smaller blocks.

In 1954, archaeologist Kamal el-Mallakh (1918-87) found a timber planked boat, buried in a pit 32.5m long near the base of the pyramid’s south face with its prow to the west. The 'Solar Barque' had been entombed by a roof of 41 limestone slabs up to 4.8m long and weighing 17-20 tonnes each. The boat was made of Lebanese cedar and acacia. It is 43.9m long and 5.9m wide, with a displacement of 45.7 tonnes and maximum draft of 1.5m. The boat's 1,224 components had been dismantled in antiquity. Re-assembly was completed in 1968 and the boat is now housed in a custom-built museum on the spot where it was found.

In the 1980s, radiocarbon dating of organic matter found in the pyramid returned a date range of 2853-3809 BC. Dating of material from other Giza sites gave similar ranges, though weathering patterns on the Sphinx seem to indicate that it might be much older. Some scientists believe stone working at Giza may have commenced as early as 10,500 BC, with the possibility that the lower part of the Great Pyramid was constructed centuries before the upper portion.

The Giza Plateau Mapping Project was launched in 1988, under Lehner’s direction, and is dedicated to researching the local geology and topography, and the construction and function of the pyramids, associated tombs and temples, the Sphinx and the nearby Old Kingdom town. The Giza Plateau model was constructed in 1990-5, and work is ongoing using computer graphics and remote sensing technology to replicate the plateau’s ancient configuration.

According to Lehner, raw materials, tools and food could have been brought to site by water along a wadi (a dry channel that flows after rainfall) that ran to the south-east of the site, dividing the plateau. Excavations show that at the mouth of the wadi was a towering masonry wall, 30m high. It formed a 200m long quay or revetment of stone blocks along the south side of the channel, and the area to the north, near the valley temples for the three pyramids, was once a harbour.

The Great Pyramid has a distinctive feature: narrow shafts rising from the Queen’s and King’s chambers. Each chamber has a pair of shafts, one on the north wall and one on the south wall. The Queen’s shafts, north and south, slope upwards at 39.7 and 39.4 degrees. The King’s shafts slope at 32.4 and 45 degrees. They were presumed to be air shafts, though the Queen's shafts do not reach the edge of the pyramid’s core. The King’s shafts do, but could have been hidden by the now absent limestone cladding. Each end of the King’s shafts was open but both ends of the Queen’s shafts were sealed.

In 1989, German engineer Rudolf Gantenbrink began computer analysis of the pyramid and became curious about the narrow shafts, which followed the same segmental pattern for most of their lengths. The walls and roof of each segment are formed from stone channels, each cut from one block. Unshaped blocks form the floor, sealing the shafts from below. The inclined shafts are fitted into the horizontal layers of the stonework between wedge-shaped blocks. Each segment is made up of four blocks (one channel, one rectangle, two wedges), occupying a space roughly 2m wide and 4m long. A series of girdle stones set vertically prevent the whole from sliding down the continuous diagonal joint at the floor of each shaft.

In 1991, Gantenbrink joined forces with Dr Rainer Stadelmann (b.1933), Director of the German Archaeological Institute, to explore the shafts with a crawler robot (the Upuaut Project). The King’s shafts were cleared and ventilation fans installed to combat rising levels of humidity that are resulting from the numbers of visitors inside the pyramid. The Queen’s shafts were investigated thoroughly.

Robotic inspections were undertaken in 1992 and 1993. From the King’s Chamber, a sled-mounted camera was towed through the shafts from a pulley on the outer face of the pyramid. On average, it found the shafts were 205mm wide and 215mm high. The south shaft exits the exterior at the 101st course, 77.6m above the pyramid’s base and 5.2m east of the central axis, and the north shaft at the 102nd course, 78.4m above base and 1.6m east of the axis.

For the Queen’s shafts Gantenbrink designed a self-propelled laser-guided robot. The north shaft proved to turn through 45 degrees, preventing the robot from progressing more than 19m. Artefacts seen included a long staff of timber, a piece of wood with two holes (possibly a handle for the double hook found by Dixon in 1872) and an hexagonal metal pole thought to have been left there by Dixon. The south shaft runs straight for about 60m, ending in a stone slab fitted with two copper handles. The slab and the adjoining shaft segment are of dressed Tura limestone. Further investigation stalled.

In 1992, ground-penetrating radar investigations, gravimetric measurements and soundings were carried out in the subterranean chamber, its pit and the corridor leading into it. This revealed a hidden shaft, approximately 1.4m square and 4.9m deep, below the approach passage and about 2.7m from the chamber’s entrance.

In 1993, during roadworks, the remains of a satellite pyramid were found in front of the Great Pyramid, about 25m south east of its south-east corner. Its base is 23m square and it has a side angle of 52 degrees. Its apex stone of Tura limestone was recovered (the second oldest ever found) and re-erected.

Investigation of the Queen's shafts resumed in 2001 using another self-propelled robot, called Pyramid Rover. It carried fixed and fibre-optic cameras and drilling equipment. It was sent into the north shaft, passing bends at 22m and 25m, presumed to have been constructed to prevent the shaft intercepting the Grand Gallery. At 27m, it found two more hexagonal metal rods also probably abandoned by Dixon.

Later that year, the Rover was sent up the south shaft, determining by echo sounding that the slab door was 50-90mm thick and drilling a 20mm hole through it. Images were sent out of the 180mm deep void behind the slab, which ended in a block of rough local limestone. A second visit to the north shaft, past the bends, encountered at 63m a slab door with copper handles similar to the one sealing the south shaft. Behind it is a small void and another limestone block, as before. Whether these secondary blocks are core stones or doors concealing more secrets is unknown (2017).

Cosmology was an important part of ancient Egyptian life, governing many rituals. Numerous studies have tried to link the alignments of the various passages and shafts in the Great Pyramid with celestial bodies, with limited success. Nevertheless, it seems possible that the four narrow shafts were physical conduits to allow the pharaoh’s soul to ascend to the celestial realm.

Research: ECPK

bibliography

"Engineering the Pyramids" by Dick Parry, The History Press, Stroud, 2013

"Ancient Egyptian Tool Technology" by F.G. Helps, International Journal for the History of Engineering & Technology, Vol.81, No.2, pp.233-243, July 2011

"The Great Pyramid Debate" by Dipayan Jana, Proceedings of the 29th Conference on Cement Microscopy, Quebec, 20-24th May 2007, accessed online

"The Complete Pyramid Sourcebook" by John DeSalvo, Great Pyramid of Giza Research Association, AuthorHouse, 2003, accessed online

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