There are five platonic solids, the tetrahedron ... A pyramid with a square base is a square-based pyramid. Image caption, 3D shapes that are non-polyhedral include cylinders, cones, and spheres.

Pyramids in Mesoamerica, such as those built by the Maya, Aztec and Teotihuacán civilizations, were monumental structures ...

The pyramid’s weight is spread out, keeping it solid. This is key ... It shows the ancient Egyptians’ advanced knowledge. Geometry was key in building the pyramids. The ancient Egyptians ...