The Great Pyramid of Giza (also called the Pyramid of Khufu and the Pyramid of Cheops) is the oldest and largest of the three pyramids in the Giza Necropolis bordering what is now El Giza, Egypt.
It is the oldest of the Seven Wonders of the Ancient World, and the only one to remain largely intact.
It is believed the pyramid was built as a tomb for fourth dynasty Egyptian pharaoh Khufu and was constructed over a 20 year period.
The mass of the pyramid is estimated at 5.9 million tonnes. The volume, including an internal hillock, is roughly 2,500,000 cubic metres. Based on these estimates, building this in 20 years would involve installing approximately 800 tonnes of stone every day.
Similarly, since it consists of an estimated 2.3 million blocks, completing the building in 20 years would involve moving an average of more than 12 of the blocks into place each hour, day and night.
Many of the casing stones and inner chamber blocks of the Great Pyramid were fit together with extremely high precision.
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 21 mm.
The sides of the square base are closely aligned to the four cardinal compass points (within 4 minutes of arc) based on true north, not magnetic north.
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 Great Pyramid of Giza is the only pyramid in Egypt known to contain both ascending and descending passages.
The main part of the Giza complex is a setting of buildings that included two mortuary temples in honor 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 surrounding the pyramid for nobles.
Explore the Pyramids - PBS
Who Built the Pyramids? - Nova
The outline of the Giza pyramids superimposed over a photograph of the stars in Orion's Belt