The Great Pyramid of Giza is a well known ancient structure on the outskirts of Cairo and in the previous two papers in this series regarding the building I established that there are errors in the surveying which, when corrected, allow the architectural design of the vertical placement of the pyramid's two main chambers to be identified.

In this paper I identify a procedural error in William Petrie's 1883 survey of the pyramid which, when corrected, allows the design of the pyramid's internal passage system to be understood. In Petrie's survey he established that the internal passage system and external faces of the pyramid are constructed at a small negative azimuth. To simplify the documentation of the resulting surveying data of the internal architecture he referenced all measurements in an easterly direction to a vertical plane running through the center of the building which is parallel to the average of the azimuths of the east and west sides of the building.

I show that when a true north elevation of the Great Pyramid is established from the original survey data, that the architect's original design of the internal passage system can be identified. From this I show that the north elevation of the building and the east elevation are designed to lock together using the vertical axis of each elevation as a common reference.

During the creation of the true north elevation, and due to the systematic design of the architecture, I show that the original orientation of the center line of the gallery within the pyramid must have been along a true east west line, that the sides of the building were constructed to a logical known azimuth, and that the rotation of the building due to tectonic plate movement over the last 4700 years can be established with precision, because one of the purposes of the architecture is to specifically allow such a measurement to be taken.