Pharaoh Netjenkhet Djoser (c. 2670 BCE) was the second king of the Third Dynasty of Egypt and the first to build in stone. Prior to Djoser’s reign, mastaba tombs were the customary form for graves: rectangular monuments made of dried clay brick which covered underground passages where the deceased was entombed. For reasons which remain unclear, Djoser’s vizier, Imhotep (c. 2667 BCE), conceived of building a more impressive tomb for his king by stacking mastabas on top of one another, progressively making them smaller, to form the shape now known as the Step Pyramid.