Search for hidden chambers in the pyramids.

The three pyramids 6f Giza are situated a few miles southwest of Cairo, Egypt. The two largest pyramids stand within a few hundred meters of each other. They were originally of almost exactly the same height (145 meters), but the Great Pyramid of Cheops has a slightly larger square base (230 meters on a side) than the Second Pyramid of Chephren (215.5 meters on a side). A photograph of the pyramids at Giza is shown as Fig. 1. Figure 2 shows the elevation cross sections of the two pyramids and indicates the contrast in architectural design. The simplicity of Chephren's pyramid, compared with the elaborate structure of his father's Great Pyramid, is explained by archeologists in terms of a "period of experimentation," ending with the construction of Cheops's pyramid (1). (The complexity of the internal architecture of the pyramids increased during the Fourth Dynasty until the time of Cheops and then gave way to quite simple designs after his time.) An alternative explanation for the sudden decrease in internal complexity from the Great Pyramid to the Second Pyramid suggested itself to us: perhaps Chephren's architects had been more successful in hiding their upper chambers than were Cheops's. The interior of the Great Pyramid was reached by the tunneling laborers of Caliph Ma-