AP® Art History · Unit 2 · Topic 2.1

Building the Pyramids at Giza

The Great Pyramid at Giza is a solid mass of stacked limestone blocks shaped so its own weight pushes outward and down into a wide, stable base, which is why it has outlasted every tower built after it.

A tower fails because it is thin and top-heavy: stack blocks straight up and the structure leans, cracks, or topples under its own weight. A pyramid solves this by spreading enormous weight across a huge base and tapering it as it rises, so every layer of stone sits on a wider layer beneath it. The shape itself resists collapse; there is no span to sag and no height without support under it.

The form developed in stages. Early tombs were mastabas, low flat-roofed rectangular boxes of mud brick or stone covering a burial chamber. Imhotep stacked six mastabas of shrinking size on top of each other for King Djoser at Saqqara, creating the Step Pyramid around 2650 BCE. Later builders filled in the steps and dressed the surface with smooth casing stones, producing the true smooth-sided pyramid form seen at Giza around 2560 BCE, built for Khufu. The Great Pyramid's face rises at roughly 51.8 degrees, found by taking the arctangent of the height, 147 meters, divided by half the base, 115 meters.

Builders aligned the four sides to true north by observing circumpolar stars, which circle the pole without setting, and marking where a chosen star rose and set on the horizon, then bisecting the angle between those two points to find true north. This precision connects to the unit's larger theme: Egyptian builders worked in grid, axis, and ratio the way Mesopotamian ziggurats worked in stacked registers, and the way Greek and Roman builders later worked in column proportion and the arch.

Key terms

Mastaba
A flat-roofed rectangular tomb with sloping sides, the earliest form Egyptian pyramids grew from.
Step pyramid
A pyramid built from stacked, shrinking mastaba-like layers, as Imhotep designed for Djoser at Saqqara.
Circumpolar stars
Stars near the celestial pole that never set, used by Egyptian builders to find true north.
Face slope
The angle a pyramid's triangular face makes with the ground, found from height and half the base length.
Casing stones
Smooth outer blocks of fine limestone added over a stepped core to create a flat-sided pyramid surface.

Watch it explained

  1. How it worksHow does a flat mastaba grow into a step pyramid and then into the smooth sided pyramid at Giza?
  2. Worked exampleFind the face slope of the Great Pyramid from its 230 m base and its 147 m original height.
  3. How it worksWalk me through aligning a pyramid's four sides to true north using only circumpolar stars.
  4. Common mistakeWhy weren't the Great Pyramids raised by armies of whipped slaves the way movies show?

Check yourself

Your turn1 of 2
The Great Pyramid at Giza originally rose about 147 meters above a square base measuring about 231 meters on each side. Using half the base length as the horizontal run beneath the sloped face, what angle, in degrees, does the face rise from the ground, using arctangent of height divided by half the base?

End of topic.