On the outskirts and southwest of Cairo lies the Giza Plateau, home to arguably the world's greatest monuments – the three great pyramids and the Great Sphinx.
The three pyramids are The Pyramid of Khufu, also known as the Great Pyramid of Giza, The Pyramid of Khafre (Khufu's son), and The Pyramid of Menkaure. Associated with each pyramid are pyramid complexes consisting of other smaller pyramids, temples, and mastabas. Mastabas are rectangular burial mounds that can be as high as 20 feet (6 m).
Also known as the Pyramid of Cheops, it is the oldest and largest of the three pyramids in the Giza pyramid complex. It is the only one of the original Seven Wonders of the Ancient World to survive. The Great Pyramid was the tallest man-made structure in the world for over 3,800 years until the Lincoln Cathedral in England was completed in 1,311 A.D.
Khufu was the second pharaoh of the Fourth Dynasty, and reigned during the 26th century B.C. It is believed that Khufu's pyramid began being built around 2,580 B.C. and it took between 10 and 20 years to build, being completed around 2,560 B.C. It is built from an estimated 2.3 million blocks of stone which were transported from nearby quarries.
The largest stones used in the pyramid are granite stones found in the "King's chamber", and they weigh a whopping 25 to 80 tons. It is estimated that 5.5 million tons of limestone, 8,000 tons of granite that was imported from Aswan, and 500,000 tons of mortar were used in the construction of the Great Pyramid. For it to be completed in 20 years; more than 12 blocks would have had to be placed every hour, night and day.
What we see today is only the underlying structure of the pyramid. Originally, it and the other two pyramids were covered in white limestone casing stones that would have made the pyramids shine, and they would have been visible from far away. The limestone casing stones were quarried from across the Nile River, and only a few remain at the base of Khufu's Pyramid and the top of Khafre's Pyramid.
Of the precision used in the placement of these casing stones, famed English archaeologist Flinders Petrie (1853 - 1942) said it was "equal to opticians' work of the present day, but on a scale of acres."
The present height of Khufu's pyramid is 138.8 meters (455.4 ft) high, with each base side 230.4 meters (755.9 ft) in length. The mass of the pyramid is estimated at 5.9 million tons, and it has an interior volume of around 2,500,000 cubic meters (88,000,000 cu ft).
The four sides of the base of the pyramid are identical to an error of only 58 millimeters in length. The sides of the square base are perfectly aligned to the four cardinal compass points to within four minutes of arc.
In the ancient Egyptian measuring system, the pyramid was 280 Egyptian Royal cubits high, by 440 cubits long at each of the four sides of its base. If you take the ratio of the length of the perimeter to the pyramid's height, it is 1760/280 Egyptian Royal Cubits. This equates to 2π to an accuracy of better than 0.05 percent.
The interior of Khufu's Pyramid contains three chambers, an unfinished chamber below the base of the pyramid, the Queen's Chamber above it, and above that, the King's Chamber.
The entrance to the Great Pyramid is on the north face, 17 meters (56 ft) above the ground. From it, there is a descending passageway to the subterranean chamber, but 28.2 meters (93 ft) from the entrance, a stone slab in the roof of the descending passageway concealed a square hole that leads to an ascending passageway that leads to both the Queen's Chamber and the Grand Gallery.
The Queen's Chamber
The Queen's Chamber is exactly centered between the north and south faces of the pyramid. It is 5.75 meters (18.9 ft) north to south, 5.23 meters (17.2 ft) east to west, and the apex of its roof is 6.23 meters (20.4 ft) high. On both the north and south walls of the Queen's Chamber are two shafts, one of which connects to the Grand Gallery, and the other ends upwards within the structure.
In 1993, German engineer Rudolf Gantenbrink used a crawler robot named Upuaut 2 to climb the shaft, and he found that after 65 m (213 ft), there was a limestone door with two eroded copper "handles".
In 2002, a National Geographic Society robot drilled a hole in the door only to find another door behind that. A 2011 study revealed a small chamber between the doors with hieroglyphs writings in red paint.
The Grand Gallery
The purpose of The Grand Gallery is not known, but it continues the slope of the Ascending Passage, and is 8.6 meters (28 ft) high and 46.68 meters (153.1 ft) long. It grows progressively narrower the higher up you go, and each roof stone fits into a slot cut in the top of the gallery like the teeth of a ratchet. This means each block is supported by the wall of the Gallery, rather than resting on the block beneath it.
The floor of the Grand Gallery is comprised of a series of steps in which are 54 slots, 27 on each side. Their purpose isn't known, but it is speculated that they held wooden beams which, in turn, held blocking stones.
The King's Chamber
The King's Chamber is 10.47 meters (34.4 ft) from east to west, 5.234 meters (17.17 ft) from north to south, and 5.852 meters (19 feet 2 inch) high. 0.91 m (3.0 ft) above the floor there are two narrow shafts in both the north and south walls that extend all the way out to the exterior of the pyramid.
The shafts appear to be aligned towards stars or areas of the northern and southern skies, and it is thought their purpose was to aid in the ascension of the king's spirit to the afterlife.
The only object found in the King's Chamber was an empty granite sarcophagus. Interestingly enough, the sarcophagus is wider than the Ascending Passage, which means that it must have been placed in the Chamber before the roof was put in place.
In 2017, a large void was found within Khufu's Pyramid by using muons. Muons are an elementary particle similar to an electron. They are a member of the lepton family, and therefore are not comprised of any other particles.
Physicists with the ScanPyramids collaboration placed a muon detector in the Queen's Chamber. Dense materials such as rock, absorb muons, while muons pass freely through the air. When more muons were received by the detector, it revealed a previously-unknown large void that is about 30 meters in length.
Computer reconstructions reveal that the void is similar in size to the Grand Gallery, and is at the same height as a number of small chambers above the King's Chamber that relieve pressure from above. The team has also located a corridor-like structure near to the surface of the pyramid that could provide a route into the void.
Khafre's Pyramid, also known as Chephren in Greek, is the second-tallest and second-largest of the Giza Plateau pyramids. It is the tomb of the Fourth-Dynasty pharaoh who ruled from c. 2,558 to 2,532 B.C. His pyramid complex consists of a valley temple, the Sphinx temple, a causeway that runs on an angle to avoid the Sphinx, a mortuary temple and the King's pyramid.
The pyramid has a base length of 215.5 m (706 ft) and rises up to a height of 136.4 meters (448 ft). It is made of limestone blocks weighing more than 2 tons each. The slope of the pyramid rises at a 53° 13' angle, which is steeper than Khufu's Pyramid, which has an angle of 51°50'24".
From the outside, Khafre's pyramid appears taller than Khufu's because it sits 10 m (33 ft) higher. Some of its casing stones were taken on Ramesses II's orders to build a temple in Heliopolis, but some were still in place in 1646 when Oxford University professor John Greaves wrote about them.
The Khafre's Pyramid was first explored during modern times by Giovanni Belzoni in 1818. He found the pyramid's original entrance located on the north side of the pyramid, and upon entering, Belzoni found an open, empty sarcophagus, with its lid broken on the floor in the burial chamber.
To the east of Khafre's Pyramid sits what remains of the mortuary temple. It is larger than previous temples, and it is the first to include all five standard elements of later mortuary temples: an entrance hall, a columned court, five niches for statues of the pharaoh, five storage chambers, and an inner sanctuary. It was built of megalithic blocks, the largest of which is 400 tons.
Menkaure's pyramid complex consists of a valley temple, a causeway, a mortuary temple, and the king's pyramid which is the smallest of the three pyramids. The king's pyramid has three subsidiaries or queen's pyramids.
Today, Menkaure's pyramid is 61 m (204 ft) tall with a base of 108.5 m. Its angle of incline is approximately 51°20′25" and it was constructed of limestone and granite. Menkaure's Pyramid shows unusual damage caused at the end of the twelfth century when Saladin's son and heir, al-Malek al-Aziz Othman ben Yusuf, attempted to demolish the pyramids, starting with Menkaure's.
He found that it was almost as expensive to demolish the pyramids as it was to build them, and after eight months, only managed to leave a gash in the north face of Menkaure's Pyramid.