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Wonder of the Ancient World
It is believed the pyramid was built as a tomb for Fourth dynasty Egyptian pharaoh Khufu and constructed over a 20 year period concluding around 2560 BC. Khufu's vizier, Hemon, or Hemiunu, is believed by some to be the architect of the Great Pyramid. It is thought that, at construction, the Great Pyramid was 280 Egyptian royal cubits tall, 146.6 meters, but with erosion and the loss of its pyramidion, its current height is 138.8 m. Each base side was 440 royal cubits, with each royal cubit measuring 0.524 meters. 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. The first precision measurements of the pyramid were done 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. Petrie found the pyramid is oriented 4' west of North and the second pyramid is similarly oriented.
The Great Pyramid was the tallest man-made structure in the world for over 3,800 years, 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, and 1 minute in angle from a perfect square. The base is horizontal and flat to within 15 mm. The sides of the square are closely aligned to the four cardinal compass points to within 3 minutes of arc and is based not on magnetic north, but true north. The design dimensions, as confirmed by Petrie's survey and all those following this, are assumed to have been 280 cubits in height by 4x440 cubits around originally, and as these proportions equate to 2π to an accuracy of better than 0.05%, this was and is considered by Petrie, I. E. S. Edwards, and Miroslav Verner to have been the deliberate design proportion. Verner wrote, "We can conclude that although the ancient Egyptians could not precisely define the value of π, in practise they used it".
Casing stones
At completion, the Great Pyramid was surfaced by white 'casing stones' - slant-faced, but flat-topped, blocks of highly polished white limestone. 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 around the base of the Great Pyramid can be seen to this day in situ displaying 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.
Construction theories
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. The disagreements center on the method by which the stones were conveyed and placed. A recent theory proposes that the building blocks were manufactured in-place from a kind of "limestone concrete". In addition to the many theories as to the techniques involved, there are also disagreements as to the kind of workforce that was used. One theory, suggested by the Greeks, posits that slaves were forced to work until the pyramid was done. This theory is no longer accepted in the modern era, however. Archaeologists believe that the Great Pyramid was built by tens of thousands of skilled workers who camped near the pyramids and worked for a salary or as a form of paying taxes until the construction was completed. The worker's 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.
Inside the Great Pyramid
There are three known chambers inside the Great Pyramid. These are arranged centrally, on the vertical axis of the pyramid. From the entrance, an 18 meter corridor leads down and splits in two directions. One way leads to the lowest and unfinished chamber. This chamber is cut into the bedrock upon which the pyramid was built. It is the largest of the three, but totally unfinished, only rough-cut into the rock. The other passage leads to the Grand Gallery (49 m x 3 m x 11 m) where it splits again. One tunnel leads to the Queen's Chamber, a misnomer, while the other winds to intersect with the descending corridor. The Grand Gallery itself features an ingenious corbel halloed design and several cut "sockets" spaced at regular intervals along the length of each side of its raised base with a "trench" running along its center length at floor level. What purpose these sockets served is unknown. An antechamber leads from the Grand Gallery to the King's Chamber.
King's Chamber
At the end of the lengthy series of entrance ways leading into the pyramid interior is the structure's main chamber, the King's Chamber. This chamber was originally 10 x 20 x 11.2 cubits, or about 5.25 m x 10.5 m x 6 m, comprising a double 10x10 cubit square, and a height equal to half the double square's diagonal. Some believe that this is consistent with the geometric methods for determining the Golden Ratio φ (phi), which can be derived from other dimensions of the pyramid, such that if φ had been the design objective, then π automatically follows to 'square the circle'.
The sarcophagus of the King's Chamber was hollowed out of a single piece of Red Aswan granite and has been found to be too large to fit through the passageway leading to the chamber. Whether the sarcophagus was ever intended to house a body is unknown. It is too short to accommodate a medium height individual without the bending of the knees, a technique not practiced in Egyptian burial, and no lid was ever found. The King's Chamber contains two small shafts that ascend out of the pyramid. These shafts were once thought to have been used for ventilation, but this idea was eventually abandoned leaving Egyptologists to now conclude they were instead used for ceremonial purposes. It is now thought that they were to allow the Pharaoh's spirit to rise up and out to heaven.
Queen's Chamber
The Queen's Chamber is the middle and the smallest, measuring approximately 5.74 by 5.23 meters, and 4.57 meters in height. Its eastern wall has a large angular doorway or niche, Egyptologist Mark Lehner believes that the Queen's chamber was intended as a serdab, a structure found in several other Egyptian pyramids, and that the niche would have contained a statue of the interred. The Ancient Egyptians believed that the statue would serve as a "back up" vessel for the Ka of the Pharaoh, should the original mummified body be destroyed. The true purpose of the chamber, however, remains uncertain. The Queens Chamber has a pair of shafts similar to those in the King's Chamber, which were explored using a robot, Upuaut 2, created by the German engineer Rudolf Gantenbrink. In 1992, Upuaut 2 discovered that these shafts were blocked by limestone "doors" with two eroded copper handles. The National Geographic Society filmed the drilling of a small hole in the southern door only to find another larger door behind it. The northern passage, which was harder to navigate due to twists and turns, was also found to be blocked by a door.
Unfinished chamber
The "unfinished chamber" lies 27.5 meters below ground level and is rough-hewn, lacking the precision of the other chambers. This chamber is dismissed by Egyptologists as being nothing more than a simple change in plans in which they believe it was intended to be the original burial chamber but later King Khufu changed his mind wanting it to be higher up in the pyramid.
From Wikipedia
http://en.wikipedia.org/wiki/Great_Pyramid_of_Giza
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