A 3D shape with all straight edges and flat faces is a polyhedron. Other 3D shapes with least one curved surface are not polyhedra. A 3D shape with regular polygonal faces, meeting at equal angles, is ...

Archaeologists have begun digging for what they think might be a pyramid hidden beneath a hill in Bosnia. Known as Visocica, the 650m (2,120ft) triangular mound, overlooking Visoko, has long been ...