The layout of the substructure was developing because of improvements in construction capabilities. Its vulnerability to the tomb robbers, however, played a more demanding role for security. The substructure as depicted here at the pyramid of Zawyet El Aryan, is an early example during the 3rd dynasty which was entirely tunneled in the rock foundation. It begins with a stairway E, near the NE corner of the step pyramid, followed by a horizontal westerly corridor which meets an upright shaft at P, on the NS axis. These are connected to a horizontally perpendicular one coming from the fishbone-like galleries in the north to the burial chamber C, under the center of the step pyramid.
(Above) The layer pyramid at Zawyet El Aryan showing the substructure in section and plan. This step pyramid dates to a king following Sekhemkhet of the mid 3rd dynasty 2700 BC. Drawn by Tarek Swelim after J. Ph-Lauer 1979
Later on in the Old Kingdom the substructure locations are shown in the diagram above. The substructure locations partly run through the building of the superstructure (the Entrance and Corridor pointing to the circumpolar region of the sky), and partly tunneled in the rock foundation (Portcullis, Sarcophagus and Burial Chamber). Being a slandered layout the tomb robbers were able to access the treasures. Consequently no pyramid with this layout has preserved its treasures.
To make it difficult for the robbers to access to the burial chamber in the Middle Kingdom the layout of the substructure becomes complicated, as shown below at the pyramid of king Ameny Qemau, 13th dynasty BC 1800. This complex arrangement was built of huge blocks of masonry in a pit open to the sky. The superstructure was constructed above the roofing which no longer exists.
(Above) The substructure of the middle kingdom pyramid of King Ameny Qemau of the mid 13th dynasty 1700 BC at south Saqqara. Drawn by Jaroslaw Dobrowolski 1997 for Nabil Swelim after Maragioglio V. and Renaldi CA.
In the figure above, the substructure is at locations K, J, E, and A, the burial chamber, sarcophagus, portcullis, polar corridor and entrance respectively. Generally, but not in a detailed manner, these features belong to all pyramids of the Old and Middle Kingdoms. They may loosely apply to other pyramids outside Egypt.