Building PYRAMIDs...

Construction
The base of the Great Pyramid forms a nearly perfect square, with only a 19-cm (about 7.5-in) difference between its longest and shortest sides, out of a total length of about 230 m (756 ft). This huge square is also almost exactly level. When newly completed, the Great Pyramid rose 146.7 m (481.4 ft)—nearly 50 stories high. The pyramid’s core probably includes a hill of unexcavated rubble, making it impossible to determine its exact number of blocks. Researchers estimate that 2.3 million blocks were used to build the Great Pyramid, with an average weight of about 2.5 metric tons per block. The largest block weighs as much as 15 metric tons.

The work of quarrying, moving, setting, and sculpting the huge amount of stone used to build the Great Pyramid was most likely accomplished by several thousand skilled workers. Thousands more unskilled laborers and supporting workers—bakers, carpenters, water carriers, and others—were also needed for the project, so that a total of as many as 35,000 men and women were involved in the project. Many archaeologists and engineers now believe that the pyramid builders were not slaves, as was previously thought, but paid laborers who took great pride in their task. Most were probably farmers, contracted to work for a limited period. Specialists, who were permanently employed by the king, filled the positions that required the most skill—architects, masons, metalworkers, and carpenters.

In building Khufu’s pyramid, the architects used techniques developed by earlier pyramid builders. They selected a site at Giza on a relatively flat area of bedrock—not sand—which provided a stable foundation. After carefully surveying the site and laying down the first level of stones, they constructed the Great Pyramid in horizontal levels, one on top of the other.

Most of the stone for the interior of the Great Pyramid was quarried immediately to the south of the construction site. The smooth exterior of the pyramid was made of a fine grade of white limestone that was quarried across the Nile. These exterior blocks had to be carefully cut, transported by river barge to Giza, and dragged up ramps to the construction site. Only a few exterior blocks remain in place at the bottom of the Great Pyramid. During the Middle Ages (5th century to 15th century) people took the rest away for building projects in the city of Cairo.

To ensure that the pyramid remained symmetrical, the exterior casing stones all had to be equal in height and width. Workers marked all the blocks to indicate the angle of the pyramid wall and trimmed the surfaces carefully so that the blocks fit together. During construction the outer surface of the stone was left unfinished; excess stone was removed later.

As the Great Pyramid rose, the workers built large ramps to drag their materials up the sides of the structure. The exact form of these ramps is not known, but scholars believe that they were probably built wrapping around the pyramid as they rose. These ramps were probably made of desert clay mixed with water and bonded with limestone debris left over from the construction work.

When the workers had completed the pyramid and installed the pyramidion, or cap stone, ramps still covered the surface of the pyramid. As the workers dismantled the ramps from the top down, they slowly exposed the pyramid’s stone surface, which stonemasons smoothed and polished. When the ramp was gone, the pyramid was displayed in its full majesty.