The substructure differs in detail from the two previous pyramids, but in its surrounding complex, it is essentially identical to the others. The absence of a sarcophagus and funerary equipment suggests that the pyramid was never used, and also that the construction never really reached an advanced stage.
In all three Step Pyramid complexes, nearly identical mortuary buildings were found in various stages of rubble. This could mean that, the pyramid complex of Zoser’s was so classical that the two subsequent architects decided to copy it exactly, only allowing themselves the privilege of modifying the substructure. It could also mean that there could have been a codex or master plan to follow in building the complex which was set down beforehand, and which succeeding architects had to follow. It is not known which theory is correct, but the latter explanation is less accepted. The master plan theory apparently has one confirming piece of evidence. This is in the shape of four small step pyramids situated several hundred miles up the Nile, in the vicinity of Thebes. Nothing is known with certainty about the history of these small pyramids. One of them, at El-Kula, was surveyed in 1949. It was then found that this pyramid was strangely oriented. Instead of each face being oriented to the cardinal points as is usual in most pyramids, each of the four corners is oriented to one of the four points.
The pyramid of El-Kula has only three steps and its base covers an approximate area of only 61 feet square. The substructures of these pyramids have not been found except for the one at Nagada. The substructure of this four-step pyramid is, simply, a pit dug very roughly from the rock and located directly beneath the center of the pyramid. Since there is no tunnel or entrance to the outside of the pyramid face, it is assumed, that this is a tomb built so that access, following burial of the body, would be impossible. That is, they believe that the pit was dug, the body interred and the entire superstructure of the pyramid was then built around and on top of the tomb, sealing it from any possible later entry. Although when it was excavated, the substructure
yielded no body, the stunned Egyptologists clung to their theory that the pit had been specifically designed as an impenetrable tomb.
Today the mystery of these four strangely located step pyramids remains. Could these pyramids possibly have been the models from which the actual pyramids in the Memphis region, several hundred miles further down the Nile, were planned or were they simply built by a group of renegade or outcast peoples who migrated to the vicinity of Thebes?
According to archaeologists, sometime at the end of the Third or the beginning of the Fourth Dynasty, a significant alteration occurred in the design of the step pyramid. The steps of the pyramid were filled in, producing four smooth faces and sloping inwards to a point at the summit, forming what has become classically known as the true pyramid.
Egyptologists believe that they have found the reason for the transition from the step pyramid to the true pyramid from investigations of the badly damaged pyramid at Meidum, about 30 miles south of Memphis. In its present condition this structure resembles a high rectangular tower rather than a pyramid.