Pyramid

A pyramid is a geometric shape formed by connecting a polygonal base and a point called the apex by triangular faces. When unspecified the base is usually assumed to be square. One of the platonic solids, the tetrahedron, is a triangular pyramid. The square and pentagonal pyramids can also be constructed with all faces regular, and so count among the Johnson solids. All pyramids are self-dual. The volume of a pyramid is A × h / 3, where A is the area of the base and h the height from the base to the apex.

Structures

Pyramid-shaped structures were built by many ancient societies. The most famous are those in Ancient Egypt, where huge pyramids built of stone were used as tombs for pharaohs. The Great Pyramid of Giza is one of the Seven Wonders of the World, and the only one of the seven to survive into modern times. The ancient Egyptians smoothed the faces of their pyramids with gold and marble, though some of the stones used for the purpose have fallen out over the centuries.

To the south of Egypt the Nubians also built pyramids. They built far more than the Egyptians, but they are much smaller. The Nubian pyramids were constucted at a much steeper angle than Egyptian ones and were not tombs, but monuments to dead kings. Pyramids were built in Nubia up until the 300s AD.

The Mesopotamians also built pyramids called ziggurats, with a distinct series of layers. In ancient times these were brightly painted. Since they were constructed of mud-brick, little remains of them. The biblical Tower of Babel is believed to be a Babylonian ziggurat.

A number of Mesoamerican cultures also built pyramid-shaped structures. These were also usually stepped, with temples on top, more similar to the Mesoptamian ziggurat than the Egyptian pyramid. The largest pyramid by volume is that of Cholula, Mexico.

There are other pyramid-shaped ancient monuments found in Central America and parts of Asia.

Esotericism

Esotericists have attributed remarkable properties to the pyramid shape and remarkable histories to historical pyramid buildings. The Great Pyramid of Giza has attracted special interest.

The pyramid shape is alleged, among other things, to keep razor blades sharp and to prevent meat from decaying. Researchers adhering to strict scientific standards have not substantiated these claims.

Related

Game show

Pyramid is the name of a game show currently in syndication.

Novel

Pyramids is a Discworld novel by Terry Pratchett; see Pyramids (Discworld).

Album

Pyramid is a concept album by the Alan Parsons Project, released in 1978.

External links

• The Uniform Polyhedra
• Virtual Reality Polyhedra The Encyclopedia of Polyhedra