<P> 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 . </P> <P> 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 2 π 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, 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 called the Diary of Merer were discovered written by some of those who delivered limestone and other construction materials from Tora to Giza . </P> <P> 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 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 . </P> <P> 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 51⁄2 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 . </P>

How many blocks did it take to build the great pyramid of khufu