The Great Pyramid of Giza

When it was built, the Great pyramid was 145.75 m (481 ft) high. Over the years, it lost 10 m (30 ft) off its top. It ranked as the tallest structure on Earth for more than 43 centuries, only to be surpassed in height in the nineteenth century AD. It was covered with a casing of stones to smooth its surface (some of the casing can still be seen near the top of Khafre's pyramid). The sloping angle of its sides is 51 degrees and 51 minutes. Each side is carefully oriented with one of the cardinal points of the compass, that is, north, south, east, and west. The horizontal cross section of the pyramid is square at any level, with each side measuring 229 m (751 ft) in length. The maximum error between side lengths is astonishingly less than 0.1%.

How Tall?

At 146.5 m (481 ft) high, the Great Pyramid stood as the tallest structure in the world for more than 4,000 years. Today it stands at 137 m (449.5 ft) high, having lost 9.5 m (31 ft) from the top.

Here's how the Great Pyramid compares to some modern structures.

How Heavy?

More than 2,300,000 limestone and granite blocks were pushed, pulled, and dragged into place on the Great Pyramid. The average weight of a block is about 2.3 metric tons (2.5 tons).

How Wide?

How much is that? Imagine a football field. Nearly 10 football fields could fit within the base. The area of the base is also equal to about seven city blocks in New York City.

The Step Pyramid - A pyramid made of large clear steps.

The Bent Pyramid - A straight sided pyramid, until near the top where it bends inward at a sharper angle.

Another mystery of the pyramids is the fact that they are exactly in line with certain stars. Most pictures of the pyramids show tham as having a rough surface with 'steps' leading all the way up. When they were first built it is known that the pyramids were covered in quartz and were very smooth and glossy which is quite hard to imagine. Over time people took the quartz, partly to make new buildings and partly to make the pyramids easier to climb. For a pyramid to look like a pyramid, each of the four triangular-shaped sides must slope up and towards each other at the same angle so that they meet at a point at the top. The builders constructed the pyramid layer by layer, starting at the bottom. They had to check their work often, for even a tiny error at the bottom could grow into a very large error by the time the workers reached the top! It has been suggested that there are enough blocks in the three pyramids above to build a 3 m (10 ft) high, 0.3 m (1 ft) thick wall around France.