Pyramid
- This article is about the polyhedron pyramid (a 3-dimensional shape); for other versions including architectural Pyramids, see Pyramid (disambiguation).
An n-sided pyramid is a Polyhedron formed by connecting an n-sided polygonal base and a point, called the Apex, by n triangular faces (n≥3). In other words, it is a Conic solid with polygonal base. When unspecified the base is usually assumed to be square. For a triangular pyramid each face can serve as base, with the opposite Vertex as apex. 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 V = 1
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3 Ah
If the base is regular and the apex is above the center, the Symmetry group of the n-sided pyramid is Cnv of order 2n, except in the case of a regular tetrahedron, which has the larger symmetry group Td of order 24, which has four versions of C3v as subgroups. The Rotation group is Cn of order n, except in the case of a regular tetrahedron, which has the larger rotation group T of order 12, which has four versions of C3 as subgroups.
Structures
- See also List of ancient pyramids by country
Pyramids are one of the largest man-made constructions ever made. The oldest pyramid is the pyramid of Hellinikon in Greece 2,720 BC. There are more than 16 pyramids spread all over Greece. More info at
Pyramid-shaped structures were built by many ancient peoples. The most famous are the Egyptian pyramids - huge pyramids built of brick or stone, used as tombs for pharaohs. The Great Pyramid of Giza is the largest in Egypt and tallest in the world. It 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 polished white limestone, though many 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 constructed 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 AD 300s.
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. Mesoamerican pyramids were also usually stepped, with temples on top, more similar to the Mesopotamian ziggurat than the Egyptian pyramid. The largest pyramid by volume is the Great Pyramid of Cholula, in the Mexican state of Puebla.
There are other pyramid-shaped ancient monuments found in parts of Asia.
Pyramids were also found in Greece. One of these pyramids in Greece is older than the pyramid of Cheops, as it was dated to 2720 BC.
There is a pyramid in ancient Rome. The 27-meter-high pyramid of Gaius Cestius was built by the end of the first century BC and still exists today, close to the Porta San Paolo.
In October 2005, archaeologist Semir Osmanagić announced that a hill near the Bosnian town of Visoko conceals a pyramid 100 metres high and perhaps 12,000 years old ,. If confirmed, this would be the oldest pyramid in Europe.
Modern pyramids
An example of a modern pyramid can be found in Paris, France, in front of the Louvre Museum.
The 32-story Pyramid Arena in Memphis, Tennessee (built 1991) was the home court for the University of Memphis men's Basketball program, and the National Basketball Association's Memphis Grizzlies until 2004.
The Walter Pyramid, home of the Basketball and Volleyball teams of the California State University, Long Beach, campus in California, United States, is an 18-story-tall blue pyramid.
The Luxor Hotel in Las Vegas, United States, is a 30-story pyramid.
Esoterism
Esoterists have attributed remarkable properties ("Pyramid power") to the pyramid shape and remarkable histories to historical pyramids; even paper pyramids are reputedly able to keep blades sharp and to prevent meat from decaying. There is no scientific evidence for these properties, though.Hierarchical structure
The hierarchical structures of some organizations are sometimes described as pyramids. This often includes sports league systems.Human pyramid
This is a stunt, performed by circus artists -sometimes even doing other tricks such as juggling while up there- or less perfectly by amateurs (often for the fun of failing and falling), whereby participants form a pyramid of layers of persons, each standing (or supporting in another way, e.g. kneeling) on two others one level lower, one half a position to the right and the other to the left.- During the Hindu festival Krishna Janmaashtami, young men form human pyramids to reach pots filled with curd and butter and suspended high above the ground as part of the Dahi-Handi ritual.
- Human pyramids are often formed to reach for the bun during the Chinese Bun Festival.
- It is also used as part of a North American college fraternity Hazing ritual, often in a variation called a
spanking pyramid.
Arts and Media
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