The centre piece of the Djoser Step Pyramid's complex is the pyramid which began life as a mastaba, although almost square rather than the usual rectangular shape. According to Lauer there were six distinct stages in the transformation from mastaba to stepped pyramid Lehner equates this to a major alteration every six years of Djoser’s reign. The original structure was built from local stone and covered in Tura limestone, a second layer of limestone was added to all four sides slightly lower than the original mastaba resulting in a small step. The east side was to be extended by eight metres but before this was completed all four sides were extended to create the bottom of a four stepped pyramid. Extensions were then made to the north and west faces resulting in a six stepped superstructure dressed in Tura limestone and the largest monument in ancient Egypt at the time.