Pyramids

A pyramid is a 3 dimensional structure consisting of at least 3 sides in which all the sides are triangles which converge at the top. The greatest and most famous pyramids were built in ancient Egypt between 2600 and 1600 BCE. They were usually tombs for Pharaohs. They were supposed to represent the rays of the sun coming down and a pathway for the Pharaoh to ascend to the Heavens. Many of them were the largest structures built in ancient times. The pyramidal shape allowed for greater height by placing the largest (heaviest) part at the bottom becoming progressively smaller going up so that each level was lighter than the one supporting it below. They required the labor of thousands of workers. The Egyptian pyramids were preceded by the zigurrats of Mesopotamia which had a partially triangular shape although they did not converge in a point at the top. The native people of Mesoamerica (Mexico and adjacent parts of Central America) independently developed a civilization during Pre-Columbian times in which stepped pyramidal buildings played a role (more like ziggurats than Egyptian pyramids).
The pyramidal shaped (actually triangular because it is 2 dimensional) pendant pictured above can be found in the Metal Jewelry Shaper web site.