Polyhedrons (8)
I believe the answer is:
pyramids
'polyhedrons' is the definition.
(pyramid is a kind of polyhedron)
This is the entire clue.
(Other definitions for pyramids that I've seen before include "Giza monuments" , "Egyptian polyhedrons" , "Giza landmarks" , "Massive royal tombs of ancient Egypt" , "Monumental tombs of the Pharoahs" .)