When layman talk about the Great Pyramids of ancient Egypt at Giza, frequently expressing doubts about the ability of the Egyptians to construct such mammoth structures, one argument that is used is the extreme precision with which a massive number of huge blocks were set. Indeed, there was in the mature pyramid structure considerable accuracy in their construction, which was needed to prevent the entire structure from tumbling down. Nevertheless, there are simply many assumptions, particularly about the Great Pyramids of Giza, that are not true. 

For example, one may find in many books that Khufu's Pyramid, greatest of all in Egypt, contains an estimated 2.3 million blocks of stone weighing on average about 2.5 tons. In the past, both professional and amateur theorists assume that the pyramids are composed of generic blocks of this weight. Next, they set about solving the problem of how the builders could have possibly raised and set so many huge blocks. But upon closer examination, few of these traditional assumptions are really valid. In fact, recent analysis has suggested that Khufu's Pyramid has far fewer large blocks than originally supposed, and those who maintain that the blocks are more or less uniformly 2.5 tons are simply wrong. 

At first glance, the sides of the Giza Pyramids, stripped of most of their smooth outer casing during the Middle Ages, look like regular steps. These are actually the courses of backing stones, so called because they once filled in the space between the pyramid core and outer casing. However, a closer examination reveals that the steps are not at all regular. In fact, rather then regular, modular, squared blocks of stone neatly stocked, there is considerable "slop factor", even in the Great Pyramid of Khufu. 

Not only are the backing stones irregular, they are also progressively smaller toward the top. Behind the backing stones, the core stones are actually even more irregular. We know this because, in the 1830s, Howard Vyse blasted a hole in the center of the south side of Khufu's's Pyramid while looking for another entrance. This wound in the pyramid can still be seen today, and in it, we can see how the builders dumped great globs of mortar and stone rubble in wide spaces between the stones. Here, there are big blocks, small chunks of rock, wedge shaped pieces, oval and trapezoidal pieces, as well as smaller stone fragments jammed into spaces as wide as 22 centimeters between larger blocks. 

In the Pyramid of Khafre, Giza's second largest structure, event the coursing of the base core stones is not uniform. The builders tailored blocks to fit the sloping bedrock that they left protruding in the core as they leveled the surrounding court and terrace. In fact, in this pyramid's northeast and southeast corners, where the downward slope of the plateau left no bedrock in the core, the builders used enormous limestone blocks, two courses thick, to level the perimeter. 

Higher up, the core is made up of very rough, irregular stones. The upper third of the pyramid core appears to be stone blocks in regular stepped courses, but on closer inspection, the heights of these steps range from ninety centimeters to 1.20 meters, and the widths of the steps vary from 23 centimeters to a meter.

Just as in the case of Khufu's's Pyramid, that of Khafre's core is made up of loose, irregular fill. There are seams and gaps in the stepped core blocks, and through these we can see limestone chips and rubble. Giovanni Belzoni, the "strong man of Egyptology", cleared out a robbers tunnel in 1818 that was dug through the center of the north side of the pyramid. However, he experienced problems because the core fabric of the pyramid kept collapsing. Vito Maragioglio and Celeste Rinaldi, who surveyed the pyramids between 1963 and 1975, wrote, "... this was due without doubt to the incompactness of the internal masonry and the lack of mortar, so that the blocks are not always in contact at the sides, and cannot mutually support each other. However, although considerable irregularity shows in the inner core of even the largest and finest pyramids at Giza, the builders did not simply pile up rubble as, in all probability, they built the core slightly ahead of the casing. There is evidence that they built up these pyramids in large chunks of structure. 

The first pyramids of Egypt were step pyramids, which are not true pyramids, lacking the smooth outer casing. Many pyramid theorists assume that a stepped core makes up the bulk of every pyramid. Indeed, the pyramid at Meidum does have such a core, made up with fine sharp corners and faces. In fact, the first true pyramids were indeed conversions of step pyramids. However, we actually do not know whether the largest pyramids of the 4th Dynasty, those usually best known to the world, are built with an inner step pyramid. 

The gash that Howard Vyse made in Khufu's Pyramid, which extends some nine meters deep into its south wall starting about eighteen courses above the base reveals nothing close to regular stairs. Not a single vertical joint corresponds with another. None of the blocks are the same size, and there are no clear impressions of regular rising joints. Even the horizontal joints are not very clear. 

However, in the eastern face of this cut, the courses are not regular, but there could be two crude steps of perhaps a large inner structure which is possibly a crude stepped core. A similar crude structure can be seen in the cores of the partially destroyed or unfinished queen's pyramids of Khufu and Menkaure, and in the gash in the north face of Menkaure's Pyramid. It appears likely that the cores of these pyramids are composed of great, rectangular blocks of crude masonry, a sort of "chunk approach" to assembling an inner step pyramid that lacks the beautifully finished faces and corners of Meidum. 

Irregardless of the irregularity of their cores, the Giza Pyramids do have the most massive, large block masonry of all Egyptian pyramids. These classic pyramids of popular imagination were built in only three generations and yet, all of the other pyramids of kings (excluding queens and other satellite pyramids) contain only 54 percent of the total mass of the pyramids of Sneferu, his son Khufu, and grandson Khafre. Many of the characteristics of these pyramids are very precise, but while they are not as perfect as many might imagine, they nevertheless represent true landmarks in human achievement. 

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