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 that make up the Giza
pyramid complex, which borders modern-day Giza in Egypt. It is the oldest of the
Seven Wonders of the Ancient World, as well as the only one that has been
preserved in its entirety.
Historians say the pyramid was constructed over a 20-year period, finishing around
2560 BC, as a tomb for Egyptian pharaoh Khufu of the Fourth Dynasty. For more
than 3,800 years, the Great Pyramid was the world’s tallest man-made building,
standing at 146.5 meters (481 feet).

It is estimated to weigh about 6 million tonnes and is made up of 2.3 million
limestone and granite blocks, some weighing up to 80 tonnes.

It was originally covered by limestone casing stones that formed a smooth outer
surface; today, only the underlying core layer can be seen, with a few casing stones
visible at the bottom. It was constructed by extracting massive stones from a quarry
and raising them into place, although there are many scientific and alternative
theories on how it was made.
Within the Great Pyramid, there are three known chambers. The pyramid’s lowest
chamber, which was unfinished, was cut into the bedrock upon which it was
constructed. Within the pyramid structure, the Queen’s Chamber and King’s
Chamber are located higher up.

The main part of the Giza complex consists of a series of structures that include two
mortuary temples dedicated to Khufu (one near the pyramid and one near the Nile),
three smaller pyramids for Khufu’s wives, an even smaller “satellite” pyramid, an
elevated causeway linking the two temples, and small mastaba tombs for nobles
surrounding the pyramid.
Egyptologists believe the pyramid was built over a 20-year period as a tomb for
Egyptian pharaoh Khufu (often referred to as “Cheops”) of the Fourth Dynasty.
Hemiunu (also known as Hemon), Khufu’s vizier, is thought by some to be the
founder of the Great Pyramid.
The Great Pyramid was originally 146.6 meters (481.0 feet) tall when it was built,
but its current height is 137 meters (449.5 feet) due to the removal of its original
casing. Given the absence of the casing, the lengths of the sides at the base are
difficult to determine, but recent analyses place them between 230.26 meters
(755.4 feet) and 230.44 meters (756.0 feet). The volume is approximately 2,300,000
cubic metres (81,000,000 cubic feet), including an internal hillock.
Egyptologist Flinders Petrie measured the pyramid for the first time in 1880–82 and
reported his findings as The Pyramids and Temples of Gizeh. Many of the Great
Pyramid’s casing stones and inner chamber blocks fit together with absolute
accuracy. The average joint opening is just 0.5 millimetres (0.020 in) wide, according
to measurements taken on the north-eastern casing stones.

For over 3,800 years, the pyramid was the world’s tallest man-made building.
The pyramid’s construction is so precise that the four sides of the base have an
average error of just 58 millimetres in length. The foundation is horizontal and flat to
within 15 mm (0.6 in) of being perfectly flat.
The four cardinal compass points are closely matched to the sides of the square
base (within four minutes of arc) centered on true north, not magnetic north, and
the finished base has a mean corner error of just 12 seconds of arc.

According to Petrie’s survey and subsequent research, the finished design
measurements were originally 280 Egyptian Royal cubits high by 440 cubits long on
each of the four sides of the tower.
1760/280 Egyptian Royal cubits have a perimeter to height ratio of 2 with a
precision of better than 0.05 percent (corresponding to the well-known
approximation of 22/7). According to some Egyptologists, this was the result of a
deliberate nature proportion. Verner wrote, “We can conclude that although the
ancient Egyptians could not precisely define the value of π, in practice they used it”.
“But these areas and circular ratio relations are so systematic that we can grant that
they were in the builder’s design,” Petrie concluded. Others contend that the ancient
Egyptians had no concept of pi and would not have thought to include it in their
monuments if they did. They assume that the observed pyramid slope is the product
of a simple seked slope option made without consideration for the finished building’s
overall size and proportions.

The Great Pyramid is made up of 2.3 million blocks, most of which are thought to
have been transported from nearby quarries. The Tura limestone for the casing was
quarried on the other side of the river. The pyramid’s largest granite stones, located
in the “King’s” chamber, weigh between 25 and 80 tonnes and were transported
from Aswan, more than 800 kilometers (500 mi) away.
The ancient Egyptians made rough blocks of stone by hammering grooves into
natural stone faces, inserting wooden wedges, and soaking them in water. The
wedges grew as the water was absorbed, breaking off workable chunks.

After the blocks were removed, they were transported to the pyramid by boat, either
up or down the Nile River. The Great Pyramid is thought to have been built with 5.5
million tonnes of limestone, 8,000 tonnes of granite (imported from Aswan), and
500,000 tonnes of mortar.
The Diary of Merer, written by a supervisor of the deliveries of limestone and other
building materials from Tura to Giza in the final year of Khufu’s reign, was discovered
in 2013 on rolls of papyrus.

White “casing stones”—slant-faced, flat-topped blocks of highly polished white
limestone—were used to finish the Great Pyramid. To achieve the necessary
measurements, these were neatly cut.
A ramp with two staircases and several post holes was discovered by complete chance.
All that is visible today is the underlying stepped core structure. A massive
earthquake in 1303 AD lowered many of the outer casing stones, which were
reportedly carted away in 1356 by Bahri Sultan An-Nasir Nasir-ad-Din al-Hasan for
use in nearby Cairo.
Muhammad Ali Pasha removed several more casing stones from the site in the early
nineteenth century to build the upper portion of his Alabaster Mosque in Cairo, not
far from Giza. The limestone casings are also visible as part of the structures. Later
explorers found huge piles of rubble at the base of the pyramids left over from the
casing stones’ ongoing collapse, which were cleared away during the site’s ongoing
excavations.
Several casing stones from the lowest course are still in place. They exhibit the
same level of craftsmanship and precision that has been noted for centuries. Petrie
discovered a new orientation in the heart and casing, which measured 193
centimeters by 25 centimeters.

He indicated that after the core was constructed, a redetermination of north was
made, but a mistake was made, and the casing was built with a different orientation.
“To put such stones in exact contact would be diligent work,” Petrie said of the
casing stones, “but to do so with cement in the joints seems almost impossible.” It
has been proposed that the mortar (Petrie’s “cement”) was responsible for
completing this nearly impossible task by providing a level bed that enabled the
masons to precisely place the stones.

Construction theories

The preparation of the pyramid is one of the mysteries of its construction.
Many alternate, often conflicting, theories on the construction methods of the
pyramid have been suggested. Others believed that slave labor was used, but
modern data gathered in the nearby workers’ camps associated with construction in
Giza indicate that thousands of conscript laborers were constructed instead.
Historians suggests that Ancient Egyptians used the same approach used for earlier
and later constructions, laying out portions of the plan on the field on a scale of 1-to1. He writes that “this working diagram will also help to produce the pyramid
architecture with unparalleled precision by any other means.”
A modern construction management research, in collaboration with Mark Lehner and
other Egyptologists, estimated that the total project needed an average workforce of
approximately 13,200 people and a maximum workforce of approximately 40,000.
Giza Pyramids
The authors of the study used critical path analysis methods which indicate that the
Great Pyramid could have been completed from start to finish in about 10 years.

Source: theafricanhistory