Egypt's Great Pyramid: Khufu's Monument, Explained

Short answer

• The Great Pyramid was built for Pharaoh Khufu (known in Greek as Cheops) of the Fourth Dynasty, around 2560 BCE. Its ancient name was Akhet Khufu, "Khufu's Horizon."
• It originally stood about 147 meters (481 feet) tall; erosion and the loss of its capstone and casing have reduced it to about 139 meters (455 feet).
• Each side of its square base measures about 230 meters (755 feet), and the finished structure contains roughly 2.3 million stone blocks, a commonly cited estimate, weighing about 5.75 million tons in total.
• It was the tallest human-made structure in the world for more than 3,800 years; the building usually credited with first exceeding it is Lincoln Cathedral in England, whose spire was completed in 1311.
• Inside are three main chambers, the ascending and descending passages, the corbelled Grand Gallery, and five stress-relieving chambers above the King's Chamber.
• In 2017 the ScanPyramids mission reported a large void, at least 30 meters long, above the Grand Gallery, detected with cosmic-ray muon imaging. What the void is for remains unknown.
• The pyramid was built not by slaves but by Egyptian laborers working in rotating crews, according to the excavated workers' town and cemetery at Giza and a contemporary foreman's diary found at Wadi el-Jarf.

The Great Pyramid of Giza is the largest pyramid in Egypt, the oldest of the Seven Wonders of the ancient world, and the only one that still stands. It was built as the tomb of Khufu, the second king of Egypt’s Fourth Dynasty, around 2560 BCE, on a limestone plateau on the west bank of the Nile opposite modern Cairo. When it was finished it stood about 147 meters (481 feet) tall, and it remained the tallest human-made structure on Earth for more than 3,800 years. Its base covers more than 13 acres, its sides align to the compass points with astonishing precision, and its interior holds chambers and passages that engineers are still mapping: in 2017, particle physicists announced a previously unknown void, at least 30 meters long, hidden above its Grand Gallery. This article sets out what the monument is, what is inside it, what the newest science has found, and how Egyptologists believe it was built.

The Monument in Numbers

Feature	Measurement
Built for	Pharaoh Khufu, Fourth Dynasty, around 2560 BCE
Original height	About 146.6 meters (481 feet), or 280 Egyptian cubits
Current height	About 138.5 to 139 meters (about 455 feet)
Base	About 230 meters (755 feet) on each side, 440 cubits
Slope	About 51 degrees 50 minutes
Stone blocks	About 2.3 million (a commonly cited estimate)
Total weight	About 5.75 million tons
Volume	About 2.6 million cubic meters

Two cautions belong with these numbers, because reference works vary slightly. First, chronologies of Khufu’s reign differ by a few decades between authorities, so the construction date is best given as “around 2560 BCE” in the mid-third millennium BCE. Second, the block count is an estimate derived from the pyramid’s volume and an assumed average block size, not a tally anyone made; the average block weighs roughly 2.5 tons, but some granite beams in the King’s Chamber weigh 25 tons or more, and a few far more than that. The 2.3 million figure is the estimate Britannica and most institutional sources use, presented here as an estimate rather than a counted fact.

Even reduced, the Great Pyramid is the largest of the three Giza pyramids, and it anchors one of the most famous landscapes on Earth: the Giza necropolis is part of the UNESCO World Heritage listing “Memphis and its Necropolis,” inscribed in 1979.

Khufu and the Giza Plateau

Khufu reigned in the 26th century BCE, at the height of Egypt’s Old Kingdom, when royal authority and the resources of the Nile valley could be concentrated on a single project for decades. The pyramid’s architect is generally presumed to have been Khufu’s vizier Hemiunu, a royal relative whose tomb stands nearby and whose statue survives in a German museum; “presumed” is the right word, because no inscription in the pyramid itself names its designer.

The Great Pyramid was the first and largest element of a complex that originally included a mortuary temple against its east face, a covered causeway running down to a valley temple near the Nile floodplain, queens’ pyramids for Khufu’s wives, cemeteries for his court, and pits holding full-size wooden boats, one of which was excavated intact and reassembled in the twentieth century. Khufu’s son Khafre built the second pyramid just to the southwest. It is slightly smaller, about 143.5 meters originally, but it stands on higher ground and keeps a cap of the original white casing stone at its summit, so in photographs it often looks like the tallest of the three. The third pyramid, built for Khafre’s son Menkaure, is far smaller at about 65 meters. The Great Sphinx, a lion’s body with a human head carved from a single outcrop of the plateau’s bedrock, guards Khafre’s causeway and is generally attributed to Khafre’s reign. Together the three pyramids and the Sphinx form the skyline that has defined Giza for four and a half millennia.

What Is Inside the Pyramid

Unlike later Egyptian royal tombs, which hide a single descending corridor, the Great Pyramid has an internal architecture found in no other pyramid, including both a descending and an ascending passage system. Its known spaces, from the bottom up, are these:

• The subterranean chamber. The descending passage, which enters the north face, runs down at an angle of about 26 degrees through the masonry and the bedrock to an unfinished chamber roughly 30 meters below ground level. It appears to be an abandoned first plan.
• The Queen’s Chamber. Partway up, the ascending passage leads to a horizontal corridor and a chamber near the pyramid’s center, 5.7 meters by 5.2 meters, with a pointed, gabled roof. “Queen’s Chamber” is a later misnomer; no queen was buried there, and its purpose is debated. Two narrow shafts rise from its walls, famously explored by small robots in modern times.
• The Grand Gallery. Above the junction, the passage continues upward as the Grand Gallery, one of the wonders of ancient engineering: a corbelled tunnel about 47 meters long and 8.6 meters high, its walls stepping inward course by course to a narrow roof, built with a precision that modern surveyors still admire.
• The King’s Chamber. At the top of the gallery, a granite-lined room about 10.5 meters by 5.2 meters holds an empty red granite sarcophagus, coarsely finished and slightly wider than the passages leading to it, which means it was placed in the chamber during construction. Two shafts angle up from this chamber toward the outside.
• The relieving chambers. Above the King’s Chamber’s flat granite ceiling sit five low compartments stacked in the masonry, discovered by the explorer Howard Vyse in 1837. They distribute the immense weight above the chamber’s roof beams, several of which are cracked even so. Quarry marks painted in some of these chambers, including the name of a work gang calling itself the “Friends of Khufu,” provide the direct inscriptional evidence that this was Khufu’s pyramid.

Everything in the burial apartment was ancient history by the time the first recorded entry was forced in the ninth century CE, traditionally under the caliph al-Ma’mun, whose tunnel is still used by visitors today. Whatever the pyramid once held was removed in antiquity; the sarcophagus stands empty.

The Big Void: What ScanPyramids Found in 2017

Because the pyramid is a protected monument, nobody can drill into it to settle arguments about its interior. Since 2015, the ScanPyramids mission, an international project coordinated by the HIP Institute and Cairo University under the supervision of Egypt’s antiquities authorities, has been imaging it instead with cosmic-ray muons: subatomic particles from space that rain through rock, absorbed more by dense stone than by empty space, so that detectors left in known chambers can build up a kind of X-ray of the mass above them.

In November 2017, in the journal Nature, the mission reported its largest result: a previously unknown void above the Grand Gallery, at least 30 meters long, with a cross-section similar to the gallery’s own. The finding carries unusual weight because it was confirmed independently by three teams using three different muon technologies, nuclear emulsion films, scintillator detectors, and gas detectors, positioned both inside the Queen’s Chamber and outside the pyramid. The team named it the ScanPyramids Big Void and was careful about what it is not: they reported a void, not a chamber, and they stated plainly that its shape, structure, and purpose are unknown. It may be a single open space, several adjacent spaces, or a sloped construction feature left by the builders; all of those are hypotheses, attributed here to the researchers who proposed them, not findings. In 2023 the same mission announced a second, smaller discovery, a corridor about 9 meters long behind the original north-face entrance, which investigators then inspected directly with an endoscopic camera. The Big Void itself remains unentered and unexplained, the first major internal structure found in the pyramid since the nineteenth century.

How Was It Built? Stone, Boats, and Sledges

No building manual survives, and the honest position of Egyptology is that the general system is well evidenced while details of the lifting method remain debated. The evidenced parts are these.

The stone. The pyramid’s core is local limestone, quarried on the plateau itself, where the quarry pits can still be seen. The outer casing was fine white limestone from Tura, across the Nile, and the granite for the King’s Chamber and its relieving spaces came from Aswan, some 800 kilometers upriver. Transport was by water wherever possible: canals and a harbor connected the plateau to the river during the building season.

The diary of Merer. In 2013, a French mission led by the Egyptologist Pierre Tallet excavated the ancient harbor of Wadi el-Jarf on the Red Sea coast and found the oldest inscribed papyri known from Egypt. Among them is the daybook of an official named Merer, whose crew of about 40 men spent months ferrying blocks of Tura limestone by boat across the Nile and along canals to the Giza building site, which the diary calls by the pyramid’s name, Akhet Khufu. The entries date to the year after the thirteenth cattle count of Khufu’s reign, late in the project, and they are the closest thing in existence to a builder’s own record of the Great Pyramid under construction.

Hauling on land. Stone moved on wooden sledges, not wheels. A famous tomb painting shows a colossal statue being dragged on a sledge while a man pours liquid on the sand in front of it, and modern experiments have confirmed that dampened sand roughly halves the friction under a sledge. Blocks were set with levers and cribbing; the fine casing stones were dressed in place to the hairline joints visitors can still see at the base.

The ramps debate. To raise blocks to the top, the builders needed ramps, but no ramp survives in recognizable form, and this is the main open question. Egyptologists have proposed, among others, a single straight ramp of mudbrick and rubble climbing one face, ramps that wrapped around the growing pyramid, zigzag ramps on a face, and an internal ramp spiraling inside the structure, a hypothesis put forward by the French architect Jean-Pierre Houdin and debated ever since. Each model has costs and problems, and the cautious summary is that some combination of ramps, levers, and labor gangs did the work over roughly two to three decades; the mechanism of the final courses is genuinely unresolved.

Who built it. Not slaves. That idea descends from Herodotus, writing two thousand years later, and from later tradition, but the archaeology says otherwise. Excavations of the workers’ settlement south of the plateau, led since the late 1980s by Mark Lehner and the Ancient Egypt Research Associates team, uncovered bakeries, breweries, and vast quantities of cattle bone, evidence of a provisioned workforce eating beef in quantity, with estimates commonly in the range of 20,000 to 30,000 people at peak, organized in rotating crews rather than a permanent slave gang. The builders’ own cemetery, found beside the pyramid in 1990, buried workers honorably in tombs within sight of the monument, treatment no slave population receives. The modern consensus of Egyptologists is that the pyramid was raised by Egyptian labor, much of it seasonal, paid in kind with food and beer, and organized with a sophistication that is itself one of the Old Kingdom’s great achievements.

Aligned to True North

One measurement captures the builders’ skill better than any superlative. Modern surveys find that the pyramid’s sides are aligned to the cardinal points, north, south, east, and west, to within a few minutes of arc, roughly a twentieth of a degree, of true north. The base is level to within a couple of centimeters across its whole 230-meter span, and the four sides differ in length by only a few centimeters. Achieving this with cord, stakes, sightings of circumpolar stars, and water-filled leveling trenches, as Egyptologists reconstruct the methods, is the practical marvel at the heart of the monument. That is the whole evidence based story of its alignment. Claims that the pyramid encodes the speed of light, the dimensions of the Earth, or messages from lost civilizations are modern inventions without support in the archaeological record, and they are outside the scope of this article.

The Missing Capstone and the Lost Casing

The pyramid visitors see today is the core, not the finished building. As completed, its faces were sheathed in polished white Tura limestone that would have made it shine in the sun, and it was crowned by a capstone, the pyramidion, which does not survive. What the capstone was made of is unknown; capstones from other pyramids are stone, and claims that this one was solid gold are speculation, not evidence. The likeliest story for the casing is mundane: a powerful earthquake in 1303 loosened many casing blocks, and in the following centuries the fine white stone was systematically stripped and carted off to build mosques, walls, and palaces in medieval Cairo, a process chronicled by medieval Arab historians. By the early nineteenth century only fragments of casing remained, mostly at the base, where some can still be seen today. The missing casing accounts for most of the lost height: the apex and capstone are gone, and the top is now a small flat platform about 9 meters short of the original 147 meters.

Frequently Asked Questions

Who built the Great Pyramid, and when?

It was built for Khufu, second king of Egypt’s Fourth Dynasty, around 2560 BCE, as his tomb and the centerpiece of his funerary complex at Giza. The attribution rests on quarry marks naming Khufu’s work gangs in the relieving chambers and on the diary of Merer, which records deliveries of casing stone to “Akhet Khufu” late in his reign.

How tall is the Great Pyramid?

Originally about 146.6 meters (481 feet). Today it is about 138.5 to 139 meters (about 455 feet), because the capstone and the white outer casing have been removed. For scale, it is roughly the height of a 45-story building, and it held the world height record for a human-made structure for more than 3,800 years.

How many blocks are in the Great Pyramid?

About 2.3 million is the commonly cited estimate, published by Britannica and other institutional sources, with an average block weight of roughly 2.5 tons and a total weight of about 5.75 million tons. Because the figure is computed from the pyramid’s volume rather than counted, sources present it as an estimate; the granite beams over the King’s Chamber alone weigh tens of tons each.

Was the Great Pyramid built by slaves?

No, on the evidence available. Excavation of the builders’ town at Giza shows a provisioned workforce housed, fed on bread, beer, and beef at scale, and buried honorably in a cemetery beside the monument. Egyptologists conclude that the labor was Egyptian, organized in rotating crews and paid in kind. The slave-built story comes from Herodotus, writing some 2,000 years after the fact.

What is the void found inside the Great Pyramid in 2017?

The ScanPyramids mission detected it with cosmic-ray muon imaging and published the result in Nature in November 2017: a previously unknown void, at least 30 meters long, sitting above the Grand Gallery. Three independent detector teams confirmed it. Nobody knows what it is for; the team that found it describes it strictly as a detected void, and proposed explanations remain hypotheses.

Why is the Great Pyramid the only surviving Wonder of the ancient world?

It is the oldest of the canonical Seven Wonders and was built of stone on a scale that made demolition unprofitable. The others, the Hanging Gardens, the Statue of Zeus, the Temple of Artemis, the Mausoleum, the Colossus, and the Pharos lighthouse, were destroyed by earthquakes, fire, or deliberate demolition over the centuries. The pyramid lost its casing and contents but kept its mountain of core stone.

Sources & references

• Encyclopaedia Britannica (britannica.com), "Great Pyramid of Giza": Khufu's tomb, completed in the early 25th century BCE in traditional dating, original height about 482 feet (147 meters), now approximately 455 feet (137 to 139 meters in modern surveys), roughly 2.3 million blocks totaling about 5.75 million tons, precise orientation to the cardinal points, the Grand Gallery and King's Chamber.
• Morishima, K., and colleagues (ScanPyramids), "Discovery of a big void in Khufu's Pyramid by observation of cosmic-ray muons," Nature, published November 2, 2017: the Big Void above the Grand Gallery, at least 30 meters long, detected with high confidence by three independent muon detection technologies; the paper states there is currently no information about the role of the void.
• Procureur, S., and colleagues (ScanPyramids), "Precise characterization of a corridor-shaped structure in Khufu's Pyramid by observation of cosmic-ray muons," Nature Communications, 2023: the North Face Corridor behind the original entrance, inspected by endoscope in 2023.
• Smithsonian Magazine (smithsonianmag.com), reporting on the Wadi el-Jarf papyri and the diary of Merer: the inspector Merer's logbook recording boat transport of Tura limestone to Akhet Khufu, from Pierre Tallet's excavations at the Red Sea harbor of Wadi el-Jarf.
• Egyptian Ministry of Tourism and Antiquities, Giza Plateau portal (giza.gov.eg), "Cheops Pyramid": present height 137 meters by the portal's figure, original height 146 meters, base sides of 230 meters, 2,300,000 blocks of limestone used.
• British Museum (britishmuseum.org), collection and educational resources on Old Kingdom Egypt and the Giza necropolis: Fourth Dynasty context, the Khafre and Menkaure pyramids, the Great Sphinx, and the workers' settlement evidence.