The Great Pyramid of Giza (also known as
the Pyramid of Khufu or
the Pyramid of Cheops) is the oldest
and largest of the three pyramids in
the Giza
pyramid complex bordering what is now El Giza, Egypt. It is the oldest of
the Seven
Wonders of the Ancient World, and the only one to remain largely intact.
Based
on a mark in an interior chamber naming the work gang and a reference to fourth dynasty Egyptian Pharaoh Khufu, Egyptologists believe
that the pyramid was built as a tomb over a 10 to 20-year period concluding
around 2560 BC. Initially at 146.5 metres (481 feet), the Great Pyramid was
the tallest
man-made structure in the world for more than 3,800 years. Originally,
the Great Pyramid was covered by casing stones that formed a smooth outer
surface; what is seen today is the underlying core structure. Some of the
casing stones that once covered the structure can still be seen around the
base. There have been varying scientific and alternative theories about the
Great Pyramid's construction techniques. Most accepted construction hypotheses
are based on the idea that it was built by moving huge stones from a quarry and dragging and
lifting them into place.
There
are three known chambers inside the Great Pyramid. The lowest chamber is cut
into the bedrock upon which the pyramid was built and was unfinished. The
so-called[1] Queen's Chamber and King's
Chamber are higher up within the pyramid structure. The main part of the Giza
complex is a setting of buildings that included two mortuary temples in
honour of Khufu (one close to the pyramid and one near the Nile), three smaller
pyramids for Khufu's wives, an even smaller "satellite" pyramid, a
raised causeway connecting the two temples, and small mastaba tombs surrounding
the pyramid for nobles.
History and description
It is
believed the pyramid was built as a tomb for Fourth Dynasty Egyptian pharaoh Khufu (often Hellenicised
as "Cheops") and was constructed over a 20-year period. Khufu's vizier, Hemiunu (also called
Hemon), is believed by some to be the architect of the Great Pyramid. It
is thought that, at construction, the Great Pyramid was originally 280
Egyptian cubits tall
(146.5 metres (480.6 ft)), but with erosion and absence of
its pyramidion, its
present height is 138.8 metres (455.4 ft). Each base side was 440 cubits, 230.4 metres
(755.9 ft) long. The mass of the pyramid is estimated at
5.9 million tonnes.
The volume, including an internal hillock, is roughly 2,500,000 cubic metres
(88,000,000 cu ft).
Based
on these estimates, building the pyramid in 20 years would involve installing
approximately 800 tonnes of stone every day. Additionally, since it consists of
an estimated 2.3 million blocks, completing the building in 20 years would
involve moving an average of more than 12 of the blocks into place each hour,
day and night. The first precision measurements of the pyramid were made
by Egyptologist Sir Flinders Petrie in
1880–82 and published as The Pyramids and
Temples of Gizeh. Almost all reports are based on his measurements.
Many of the casing stones and inner chamber blocks of the Great Pyramid fit
together with extremely high precision. Based on measurements taken on the
northeastern casing stones, the mean opening of the joints is only 0.5
millimetre wide (1/50 of an inch).
The
pyramid remained the tallest
man-made structure in the world for over 3,800 years, unsurpassed
until the 160-metre-tall (520 ft) spire of Lincoln Cathedral was
completed c. 1300. The accuracy of the pyramid's workmanship is such that
the four sides of the base have an average error of only 58 millimetres in
length. The base is horizontal and flat to within ±15 mm
(0.6 in). The sides of the square base are closely aligned to the
four cardinal compass points (within four minutes of arc) based
on true north,
not magnetic north, and
the finished base was squared to a mean corner error of only 12 seconds of arc.
The completed design dimensions, as suggested by Petrie's
survey and subsequent studies, are estimated to have originally been 280
royal cubits high by 440 cubits long at each
of the four sides of its base. The ratio of the perimeter to height of 1760/280
royal cubits equates to 2πto an accuracy of better than 0.05% (corresponding to the well-known
approximation of π as 22/7). Some Egyptologists consider
this to have been the result of deliberate design proportion. Verner wrote,
"We can conclude that although the ancient Egyptians could not precisely
define the value of π, in practice they used
it". Petrie, author of Pyramids and Temples of Gizeh concluded: "but these
relations of areas and of circular ratio are so systematic that we should grant
that they were in the builder's design". Others have argued that the
Ancient Egyptians had no concept of pi and
would not have thought to encode it in their monuments. They believe that the
observed pyramid slope may be based on a simple seked slope
choice alone, with no regard to the overall size and proportions of the
finished building. In 2013 rolls of papyrus were discovered written by
some of those who delivered stone and other construction materials to Khufu's
brother at Giza.
Materials
The
Great Pyramid consists of an estimated 2.3 million blocks which most
believe to have been transported from nearby quarries. The Tura limestone used for the
casing was quarried across the river. The largest granite stones in the
pyramid, found in the "King's" chamber, weigh 25 to 80 tonnes and were transported
from Aswan, more than
800 km (500 mi) away. Traditionally, ancient Egyptians cut stone
blocks by hammering into them some wooden wedges, which were then soaked with
water. As the water was absorbed, the wedges expanded, causing the rock to
crack. Once they were cut, they were carried by boat either up or down
the Nile River to
the pyramid. It is estimated that 5.5 million tonnes of limestone,
8,000 tonnes of granite (imported from Aswan), and 500,000 tonnes of mortar
were used in the construction of the Great Pyramid.
Casing stones
At
completion, the Great Pyramid was surfaced by white "casing
stones" – slant-faced, but flat-topped, blocks of highly polished
white limestone.
These were carefully cut to what is approximately a face slope with a seked of 5½ palms to give
the required dimensions. Visibly, all that remains is the underlying stepped
core structure seen today. In AD 1303, a massive earthquake loosened
many of the outer casing stones, which were then carted away by Bahri Sultan An-Nasir
Nasir-ad-Din al-Hasan in 1356 to build mosques and fortresses in nearby Cairo. Many more casing stones
were removed from the great pyramids by Muhammad Ali Pasha in the early 19th
century to build the upper portion of his Alabaster Mosque in
Cairo not far from Giza. These limestone casings can still be seen as parts of
these structures. Later explorers reported massive piles of rubble at the base
of the pyramids left over from the continuing collapse of the casing stones,
which were subsequently cleared away during continuing excavations of the site.
Nevertheless,
a few of the casing stones from the lowest course can be seen to this day in situ around the base of the Great
Pyramid, and display the same workmanship and precision that has been reported
for centuries. Petrie also
found a different orientation in the core and in the casing measuring
193 centimetres ± 25 centimetres. He suggested a redetermination of north
was made after the construction of the core, but a mistake was made, and the
casing was built with a different orientation. Petrie related the precision of
the casing stones as to being "equal to opticians' work of the present
day, but on a scale of acres" and "to place such stones in exact
contact would be careful work; but to do so with cement in the joints seems
almost impossible". It has been suggested it was the mortar (Petrie's
"cement") that made this seemingly impossible task possible,
providing a level bed, which enabled the masons to set the stones exactly.
Construction theories
Clay
seal bearing the name of Khufu from the great pyramid. On display at the Musée du Louvre.
Many
alternative, often contradictory, theories have been proposed regarding the
pyramid's construction techniques. Many disagree on whether the blocks
were dragged, lifted, or even rolled into place. The Greeks believed
that slave labour was used, but modern discoveries made at nearby workers'
camps associated with construction at Giza suggest that it was built instead by
tens of thousands of skilled workers. Verner posited that the labour was
organized into a hierarchy,
consisting of two gangs of
100,000 men, divided into five zaa or phyle of
20,000 men each, which may have been further divided according to the skills of
the workers.
One
mystery of the pyramid's construction is its planning. John Romer suggests
that they used the same method that had been used for earlier and later
constructions, laying out parts of the plan on the ground at a 1-to-1 scale. He
writes that "such a working diagram would also serve to generate the
architecture of the pyramid with precision unmatched by any other
means". He also argues for a 14-year time span for its
construction. A modern construction management study, in association
with Mark Lehner and
other Egyptologists, estimated that the total project required an average
workforce of 14,567 people and a peak workforce of roughly 40,000. Without the
use of pulleys, wheels, or iron tools, they used critical path
analysis methods, which suggest that the Great Pyramid was completed
from start to finish in approximately 10 years.
Interior
The
original entrance to the Great Pyramid is on the north, 17 metres (56 ft)
vertically above ground level and 7.29 metres (23.9 ft) east of the centre
line of the pyramid. From this original entrance, there is a Descending Passage
0.96 metres (3.1 ft) high and 1.04 metres (3.4 ft) wide, which goes
down at an angle of 26° 31'23" through the masonry of the pyramid and then
into the bedrock beneath it. After 105.23 metres (345.2 ft), the passage
becomes level and continues for an additional 8.84 metres (29.0 ft) to the
lower Chamber, which appears not to have been finished. There is a continuation
of the horizontal passage in the south wall of the lower chamber; there is also
a pit dug in the floor of the chamber. Some Egyptologists suggest that this
Lower Chamber was intended to be the original burial chamber, but Pharaoh Khufu
later changed his mind and wanted it to be higher up in the pyramid.
28.2
metres (93 ft) from the entrance is a square hole in the roof of the
Descending Passage. Originally concealed with a slab of stone, this is the
beginning of the Ascending Passage. The Ascending Passage is 39.3 metres
(129 ft) long, as wide and high as the Descending Passage and slopes up at
almost precisely the same angle to reach the Grand Gallery. The lower end of
the Ascending Passage is closed by three huge blocks of granite, each about 1.5
metres (4.9 ft) long. One must use the Robbers' Tunnel (see below) to
access the Ascending Passage. At the start of the Grand Gallery on the
right-hand side there is a hole cut in the wall. This is the start of a
vertical shaft which follows an irregular path through the masonry of the
pyramid to join the Descending Passage. Also at the start of the Grand Gallery
there is the Horizontal Passage leading to the "Queen's Chamber". The
passage is 1.1m (3'8") high for most of its length, but near the chamber
there is a step in the floor, after which the passage is 1.73 metres
(5.7 ft) high.
Queen's Chamber
The
"Queen's Chamber" is exactly halfway between the north and south
faces of the pyramid and measures 5.75 metres (18.9 ft) north to south,
5.23 metres (17.2 ft) east to west, and has a pointed roof with an apex
6.23 metres (20.4 ft) above the floor. At the eastern end of the chamber
there is a niche 4.67
metres (15.3 ft) high. The original depth of the niche was 1.04 metres
(3.4 ft), but has since been deepened by treasure hunters.
In the
north and south walls of the Queen's Chamber there are shafts, which unlike
those in the King's Chamber that immediately slope upwards (see below), are
horizontal for around 2 m (6.6 ft) before sloping upwards. The
horizontal distance was cut in 1872 by a British engineer, Waynman Dixon, who
believed a shaft similar to those in the King's Chamber must also exist. He was
proved right, but because the shafts are not connected to the outer faces of
the pyramid or the Queen's Chamber, their purpose is unknown. At the end of one
of his shafts, Dixon discovered a ball of black diorite (a type of rock)
and a bronze implement of unknown purpose. Both objects are currently in the
British Museum.
The
shafts in the Queen's Chamber were explored in 1993 by the German engineer
Rudolf Gantenbrink using a crawler robot he designed, Upuaut
2. After a climb of 65 m (213 ft), he discovered that
one of the shafts was blocked by limestone "doors" with two eroded
copper "handles". Some years later the National
Geographic Society created a similar robot which, in September 2002,
drilled a small hole in the southern door, only to find another door behind
it. The northern passage, which was difficult to navigate because of
twists and turns, was also found to be blocked by a door.
Research
continued in 2011 with the Djedi Project. Realizing
the problem was that the National
Geographic Society's camera was only able to see straight ahead of it, they
instead used a fiber-optic "micro snake camera"
that could see around corners. With this they were able to penetrate the first
door of the southern shaft through the hole drilled in 2002, and view all the
sides of the small chamber behind it. They discovered hieroglyphs written in
red paint. They were also able to scrutinize the inside of the two copper
"handles" embedded in the door, and they now believe them to be for
decorative purposes. They also found the reverse side of the "door"
to be finished and polished, which suggests that it was not put there just to
block the shaft from debris, but rather for a more specific reason.
Grand Gallery
The
Grand Gallery continues the slope of the Ascending Passage, but is 8.6 metres
(28 ft) high and 46.68 metres (153.1 ft) long. At the base it is 2.06
metres (6.8 ft) wide, but after 2.29 metres (7.5 ft) the blocks of
stone in the walls are corbelled inwards
by 7.6 centimetres (3.0 in) on each side. There are seven of these steps,
so, at the top, the Grand Gallery is only 1.04 metres (3.4 ft) wide. It is
roofed by slabs of stone laid at a slightly steeper angle than the floor of the
gallery, so that each stone fits into a slot cut in the top of the gallery like
the teeth of a ratchet.
The purpose was to have each block supported by the wall of the Gallery rather
than resting on the block beneath it, which would have resulted in an
unacceptable cumulative pressure at the lower end of the Gallery.
At the
upper end of the Gallery on the right-hand side there is a hole near the roof
that opens into a short tunnel by which access can be gained to the lowest of
the Relieving Chambers. The other Relieving Chambers were discovered in
1837-1838 by Colonel Howard
Vyse and J.
S. Perring, who dug tunnels upwards using blasting powder.
The
floor of the Grand Gallery consists of a shelf or step on either side, 51
centimetres (20 in) wide, leaving a lower ramp 1.04 metres (3.4 ft)
wide between them. In the shelves there are 54 slots, 27 on each side matched
by vertical and horizontal slots in the walls of the Gallery. These form a
cross shape that rises out of the slot in the shelf. The purpose of these slots
is not known, but the central gutter in the floor of the Gallery, which is the
same width as the Ascending Passage, has led to speculation that the blocking
stones were stored in the Grand Gallery and the slots held wooden beams to
restrain them from sliding down the passage. This, in turn, has led to the
proposal that originally many more than 3 blocking stones were intended, to
completely fill the Ascending Passage.
At the
top of the Grand Gallery, there is a step giving onto a horizontal passage some
metres long and approximately 1.02 metres (3.3 ft) in height and width, in
which can be detected four slots, three of which were probably intended to hold
granite portcullises.
Fragments of granite found by Petrie in the
Descending Passage may have come from these now-vanished doors.
King's Chamber
The
"King's Chamber" is 10.47 metres (34.4 ft) from east to
west and 5.234 metres (17.17 ft) north to south. It has a flat roof 5.852
metres (19 feet 2 inch) above the floor. 0.91 m (3.0 ft) above the
floor there are two narrow shafts in the north and south walls (one is now
filled by an extractor fan in an attempt to circulate air inside the pyramid).
The purpose of these shafts is not clear: they appear to be aligned towards
stars or areas of the northern and southern skies, yet one of them follows
a dog-leg course through
the masonry, indicating no intention to directly sight stars through them. They
were long believed by Egyptologists to be "air shafts" for
ventilation, but this idea has now been widely abandoned in favour of the
shafts serving a ritualistic purpose associated with the ascension of the
king’s spirit to the heavens.
The
King's Chamber is entirely faced with granite. Above the roof, which is formed
of nine slabs of stone weighing in total about 400 tons, are five compartments
known as Relieving Chambers. The first four, like the King's Chamber, have flat
roofs formed by the floor of the chamber above, but the final chamber has a
pointed roof. Vyse suspected the presence of upper chambers when he found that
he could push a long reed through a crack in the ceiling of the first chamber.
From lower to upper, the chambers are known as "Davison's
Chamber", "Wellington's
Chamber", "Nelson's
Chamber", "Lady
Arbuthnot's Chamber", and "Campbell's
Chamber". It is believed that the compartments were intended to safeguard
the King's Chamber from the possibility of a roof collapsing under the weight
of stone above the Chamber. As the chambers were not intended to be seen, they
were not finished in any way and a few of the stones still retain masons' marks
painted on them. One of the stones in Campbell's Chamber bears a mark,
apparently the name of a work gang.
The
only object in the King's Chamber is a rectangular granite sarcophagus,
one corner of which is broken. The sarcophagus is slightly larger than the
Ascending Passage, which indicates that it must have been placed in the Chamber
before the roof was put in place. Unlike the fine masonry of the walls of the
Chamber, the sarcophagus is roughly finished, with saw marks visible in several
places. This is in contrast with the finely finished and decorated sarcophagi
found in other pyramids of the same period. Petrie suggested
that such a sarcophagus was intended but was lost in the river on the way north
from Aswan and a
hurriedly made replacement was used instead.
Modern entrance
Today
tourists enter the Great Pyramid via the Robbers' Tunnel, a tunnel purportedly
created around AD 820 by Caliph al-Ma'mun's workmen using
a battering ram. The tunnel is cut straight through the masonry of the
pyramid for approximately 27 metres (89 ft), then turns sharply left to
encounter the blocking stones in the Ascending Passage. It is believed that
their efforts dislodged the stone fitted in the ceiling of the Descending
Passage to hide the entrance to the Ascending Passage and it was the noise of
that stone falling and then sliding down the Descending Passage, which alerted
them to the need to turn left. Unable to remove these stones, however, the
workmen tunnelled up beside them through the softer limestone of the Pyramid
until they reached the Ascending Passage. It is possible to enter the
Descending Passage from this point, but access is usually forbidden.
Pyramid complex
The
Great Pyramid is surrounded by a complex of several buildings including small
pyramids. The Pyramid Temple, which stood on the east side of the pyramid and
measured 52.2 metres (171 ft) north to south and 40 metres (130 ft)
east to west, has almost entirely disappeared apart from the black basalt
paving. There are only a few remnants of the causeway which linked the pyramid
with the valley and the Valley Temple. The Valley Temple is buried beneath the
village of Nazlet el-Samman; basalt paving and limestone walls have been found
but the site has not been excavated. The basalt blocks show "clear
evidence" of having been cut with some kind of saw with an estimated
cutting blade of 15 feet (4.6 m) in length, capable of cutting at a rate
of 1.5 inches (38 mm) per minute. John Romer suggests
that this "super saw" may have had copper teeth and weighed up to 300
pounds (140 kg). He theorizes that such a saw could have been attached to
a wooden trestle and
possibly used in conjunction with vegetable oil, cutting sand, emery or pounded
quartz to cut the blocks, which would have required the labour of at least a
dozen men to operate it.
On the
south side are the subsidiary pyramids, popularly known as Queens' Pyramids.
Three remain standing to nearly full height but the fourth was so ruined that
its existence was not suspected until the recent discovery of the first course
of stones and the remains of the capstone. Hidden beneath the paving around the
pyramid was the tomb of Queen Hetepheres I,
sister-wife of Sneferu and
mother of Khufu.
Discovered by accident by the Reisner expedition, the burial was intact, though
the carefully sealed coffin proved to be empty.
The
Giza pyramid complex, which includes among other structures the pyramids of
Khufu, Khafreand Menkaure, is
surrounded by a cyclopean stone
wall, the Wall of the Crow. Mark Lehner has
discovered a worker's town outside of the wall, otherwise known as "The
Lost City", dated by pottery styles, seal impressions, and stratigraphy to have
been constructed and occupied sometime during the reigns of Khafre (2520–2494
BC) and Menkaure (2490–2472 BC). Recent discoveries by Mark Lehner and his
team at the town and nearby, including what appears to have been a thriving
port, suggest the town and associated living quarters consisting of barracks
called "galleries" may not have been for the pyramid workers after
all, but rather for the soldiers and sailors who utilized the port. In light of
this new discovery, as to where then the pyramid workers may have lived Lehner
now suggests the alternative possibility they may have camped on the ramps he
believes were used to construct the pyramids or possibly at nearby quarries.
In the
early 1970s, the Australian archaeologist Karl
Kromer excavated a mound in the South Field of the plateau. This mound
contained artefacts including mudbrick seals of Khufu, which he identified with
an artisans' settlement. Mudbrick buildings just south of Khufu's Valley
Temple contained mud sealings of Khufu and have been suggested to be a
settlement serving the cult of Khufu after his death. A worker's cemetery
used at least between Khufu's reign and the end of the Fifth Dynasty was
discovered south of the Wall of the Crow by Zahi Hawassin 1990.
Boats
There
are three boat-shaped pits around the pyramid, of a size and shape to have held
complete boats, though so shallow that any superstructure, if there ever was
one, must have been removed or disassembled. In May 1954, the Egyptian
archaeologist Kamal
el-Mallakhdiscovered a fourth pit, a long, narrow rectangle, still covered
with slabs of stone weighing up to 15 tons. Inside were 1,224 pieces of wood,
the longest 23 metres (75 ft) long, the shortest 10 centimetres
(0.33 ft). These were entrusted to a boat builder, Haj Ahmed Yusuf, who
worked out how the pieces fit together. The entire process, including
conservation and straightening of the warped wood, took fourteen years.
The
result is a cedar-wood boat 43.6 metres (143 ft) long, its timbers held
together by ropes, which is currently housed in a special boat-shaped,
air-conditioned museum beside the pyramid. During construction of this museum,
which stands above the boat pit, a second sealed boat pit was discovered. It
was deliberately left unopened until 2011 when excavation began on the boat.
Looting
Although
succeeding pyramids were smaller, pyramid building continued until the end of
the Middle Kingdom. However, as authors Briar and Hobbs claim, "all the
pyramids were robbed" by the New Kingdom, when the
construction of royal tombs in a desert valley, now known as the Valley of the Kings,
began. Joyce
Tyldesley states that the Great Pyramid itself "is known to have
been opened and emptied by the Middle Kingdom", before the Arab caliph Abdullah al-Mamun entered
the pyramid around AD 820.
I. E. S. Edwards discusses Strabo's mention that the
pyramid "a little way up one side has a stone that may be taken out, which
being raised up there is a sloping passage to the foundations". Edwards
suggested that the pyramid was entered by robbers after the end of the Old Kingdom
and sealed and then reopened more than once until Strabo's door was added. He
adds: "If this highly speculative surmise be correct, it is also necessary
to assume either that the existence of the door was forgotten or that the
entrance was again blocked with facing stones", in order to explain why
al-Ma'mun could not find the entrance.
He also
discusses a story told by Herodotus.
Herodotus visited Egypt in the 5th century BC and recounts a story that he was
told concerning vaults under the pyramid built on an island where the body of
Cheops lies. Edwards notes that the pyramid had "almost certainly been
opened and its contents plundered long before the time of Herodotus" and
that it might have been closed again during the Twenty-sixth
Dynasty of Egypt when other monuments were restored. He suggests that
the story told to Herodotus could have been the result of almost two centuries
of telling and retelling by Pyramid guides.