The Great Pyramid of Giza, in 2005. Built c. 2560 BC, it
is the oldest and largest of the three
pyramids in the
Giza Necropolis.
Great Pyramid of Giza (also called the
Pyramid of Khufu and the Pyramid of Cheops) is the oldest
and largest of the three
pyramids in the
Giza Necropolis bordering what is now El Giza,
Egypt,
and is the only one of the
Seven Wonders of the Ancient World that survives substantially
intact. It is believed the pyramid was built as a tomb for
fourth dynasty
Egyptian Pharaoh
Khufu
(Cheops in Greek) and constructed over a 20 year period concluding
around 2540 BC. The Great Pyramid was the
tallest man-made structure in the world for over 3,800 years.
Originally the Great Pyramid was covered by casing stones that
formed a smooth outer surface, and 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 regarding the Great
Pyramid's construction techniques. Most accepted construction
theories 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 Great Pyramid of Giza is the main part of a complex
setting of buildings that included two
mortuary temples in honor 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.
Building of the Great pyramid of Giza
It is believed the pyramid was built as a tomb
for
Fourth dynasty
Egyptian pharaoh
Khufu
and constructed over a 14[2]
to 20 year period concluding around 2540 BC.[3]
Khufu's
vizier,
Hemon, or
Hemiunu, is believed by some to be the architect of the Great
Pyramid.[4]
It is thought that, at construction, the Great Pyramid was
originally 280 Egyptian
cubits tall, 146.59 metres (480.94 ft) but with
erosion and the loss of its
pyramidion, its current height is 138.74 metres (455.18 ft).
Each base side was 440 royal cubits, 230.37 metres (755.81 ft) in
length. A royal cubit measures 0.524 meters.[5]
The total mass of the pyramid is estimated at 5.9 million tonnes.
The volume, including an internal hillock, is believed to be roughly
2,500,000 cubic meters.[6]
Based on these estimates, building this in 20 years would involve
installing approximately 800 tonnes of stone every day. The first
precision measurements of the pyramid were done by
Egyptologist
Sir Flinders Petrie in 1880ń82 and published as The Pyramids
and Temples of Gizeh.[7]
Almost all reports are based on his measurements. Many of the casing
stones and interior chamber blocks of the great pyramid were fit
together with extremely high precision. Based on measurements taken
on the north eastern casing stones, the mean opening of the joints
are only 0.5 millimeters wide (1/50th of an inch).[8]
The pyramid remained the
tallest man-made structure in the world for over 3,800 years,[9]
unsurpassed until the 160 meter tall 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 a
mean error of only 58 millimeter in length
[10] The base is horizontal and flat
to within 15 mm. The sides of the square base are closely aligned to
the four cardinal compass points (within 4 minutes
of arc)[11]
based on
true north, not
magnetic north[12],
and the finished base was squared to a mean corner error of only 12
seconds of arc[13].
The completed design dimensions, as suggested by Petrie's survey and
later studies, are estimated to have originally been 280 cubits in
height by 440 cubits in length at each of the four sides of its
base. These proportions equate to
π/2 to an
accuracy of better than 0.05% (corresponding to the approximation of
π as 22/7). Some Egyptologists consider this to have been the result
of deliberate design proportion[14].
Verner wrote, "We can conclude that although the ancient Egyptians
could not precisely define the value of π, in practise they used
it".[15]
Petrie, author of ëThe Pyramids and Temples of Gizeh', who was the
first accurate surveyor of Giza and the excavator and surveyor of
the Pyramid of Meidum, concluded: "but these relations of areas and
of circular ratio are so systematic that we should grant that they
were in the builders design".[16]
Earlier in the chapter he wrote more specifically, that: ěWe
conclude therefore that the approximation of 7 to 22 as the ratio of
diameter to circumference was recognisedî.[17]
These proportions equated to the four outer faces sloping by
approximately 51.842† or 51† 50' 35", which would have been
understood and expressed by the Ancient Egyptians as a
seked
slope of 5 1/2 palms
[18].
Giza's Materials
The Great Pyramid consists of more than 2.3
million limestone blocks. The Egyptians obtained the majority of the
limestone blocks from a nearby quarry. The Tufa 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 more than 500 miles away from Aswan.
Traditionally, ancient Egyptians cut stone blocks by hammering
wedges into the stone which were then soaked with water. 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.[19]
Casing stones
At completion, the Great Pyramid was surfaced by
white 'casing stones' ń 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 5 1/2 palms to give the required overall dimensions. Visibly, all
that remains is the underlying step-pyramid core structure seen
today. In AD 1301, 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 in order to
build
mosques and
fortresses in nearby
Cairo.
The stones can still be seen as parts of these structures to this
day. 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, many of the casing stones can
be seen to this day in situ around the base of the Great Pyramid,
and display the same workmanship and precision as has been reported
for centuries. Petrie also found a different orientation in the core
and in the casing measuring 193 centimeters ± 25 centimeters. 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.[20]
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."[21]
Construction
theories
Many alternative, often contradictory, theories
have been proposed regarding the Pyramid's construction techniques.[22]
Not all even agree that the blocks were quarried, they might
conceivably have been cast[citation
needed]. However, most accept it was built by moving
huge stones from a quarry, being only unable to agree whether they
were dragged, lifted or even rolled into place. The
Greeks
believed that
slave labour was used but modern Egyptologists accept that it
was built by many tens of thousands of skilled workers. They camped
near the pyramids and worked for a salary or as a form of paying
taxes until the construction was completed.[citation
needed] Their cemeteries were discovered in 1990 by
archaeologists
Zahi Hawass and
Mark Lehner. Verner posited that the labor 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.[23]
One of the mysteries of the pyramid's
construction is how they planned its construction. 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 a
precision unmatched by any other means." He devotes a chapter of his
book to the physical evidence that there was such a plan.[24]
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