For other meanings, see pyramid . ]] A pyramid is any three-dimensional polyhedron where the faces other than the base are triangular and converge on one point, called the apex. The base of a pyramid can be any polygon; it is typically a square or a triangle, leading to four or three non-base faces. A pyramid is said to be regular if its base is a regular polygon and its upper faces are congruent isosceles triangles. Cutting off the top of a pyramid, using a plane parallel to the plane of the base, leaves a frustrum of a pyramid, sometimes called a flat-topped pyramid, though it no longer satisfies the definition of a pyramid. Ancient monuments Pyramid-shaped structures were built by many ancient civilizations. China There are many flat-topped pyramids in China. The First Emperor of Qin (circa 221 B.C.) was buried under a large p

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