Wikipedia: Pyramid

1. 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 square pyramid is l*w*h/3, where l and h are the length and width of the base and h the height from the base to the apex.
2. In Ancient Egypt, huge pyramids made of rocks were used as tomb?s for pharaohs. The Great Pyramid of Giza is one of the Seven Wonders of the World. Other pyramid-shaped ancient monuments are found in Central America and parts of Asia.
3. Concept album by the Alan Parsons Project, released in 1978.