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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 present-day Giza in Greater Cairo, Egypt. It is the oldest of the Seven Wonders of the Ancient World, and the only one to remain largely intact.

Egyptologists believe that the pyramid was built as a tomb for the Fourth Dynasty Egyptian pharaoh Khufu over a 20-year period concluding around 2560 BC. Initially standing at 146.5 metres (481 feet), the Great Pyramid was the tallest man-made structure in the world for more than 3,800 years. It is estimated to weigh approximately 6 million tonnes, and consists of 2.3 million blocks of limestone and granite, some weighing as much as 80 tonnes. It was originally covered by limestone casing stones that formed a smooth outer surface; what is seen today is the underlying core structure, although a few casing stones can still be seen at the base. It was built by extracting huge stones from a quarry and lifting them into place, but there are varying scientific and alternative theories about the exact construction technique.

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 Queen's Chamber and King's Chamber are higher up within the pyramid structure. The main part of the Giza complex is a set 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 for nobles surrounding the pyramid.

The Great Pyramid of Giza in March 2005:

Egyptologists concluded the pyramid was built as a tomb for the Fourth Dynasty Egyptian pharaoh Khufu (often Hellenized 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 146.6 metres (481.0 ft) tall, but with the removal of its original casing, its present height is 137 metres (449.5 ft). The lengths of the sides at the base are difficult to reconstruct, given the absence of the casing, but recent analyses put them in a range between 230.26 metres (755.4 ft) and 230.44 metres (756.0 ft). The volume, including an internal hillock, is roughly 2,300,000 cubic metres (81,000,000 cu ft).

The first precise measurements of the pyramid were made by Egyptologist Sir Flinders Petrie in 1880–82 and published as The Pyramids and Temples of Gizeh. 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 north-eastern casing stones, the mean opening of the joints is only 0.5 millimetres (0.020 in) wide.

The pyramid remained the tallest man-made structure in the world for over 3,800 years. The accuracy of the pyramid's workmanship is such that the four sides of the base have an average error of only 58 millimetres (2.3 inches) in length. The base is horizontal and flat to within 21 mm (0.8 in). The sides of the square base are closely aligned to the four cardinal compass points, 3 Minutes and 6 seconds of arc[10] off 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 Egyptian 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 Egyptian Royal cubits equates to 2π to an accuracy of better than 0.05 percent (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 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.

Map:

The Great Pyramid Of Giza