Hidden ramps may solve the mystery of the Great Pyramids construction.

Of the seven wonders of the ancient world, only the Great Pyramid of Giza remains. An estimated 2 million stone blocks weighing an average of 2.5 tons went into its construction. When completed, the 481-foot-tall pyramid was the worlds tallest structure, a record it held for more than 3,800 years, when Englands Lincoln Cathedral surpassed it by a mere 44 feet.

We know who built the Great Pyramid: the pharaoh Khufu, who ruled Egypt about 2547-2524 B.C. And we know who supervised its construction: Khufus brother, Hemienu. The pharaohs right-hand man, Hemienu was "overseer of all construction projects of the king" and his tomb is one of the largest in a cemetery adjacent to the pyramid.

Modern scholars have favored these two original theories, but deep in their hearts, they know that neither one is correct. A radical new one, however, may provide the solution. If correct, it would demonstrate a level of planning by Egyptian architects and engineers far greater than anything ever imagined before.

The External Ramp and Crane Theories The first theory is that a ramp was built on one side of the pyramid and as the pyramid grew, the ramp was raised so that throughout the construction, blocks could be moved right up to the top. If the ramp were too steep, the men hauling the blocks would not be able to drag them up. An 8-percent slope is about the maximum possible, and this is the problem with the single ramp theory. With such a gentle incline, the ramp would have to be approximately one mile long to reach the top of the pyramid. But there is neither room for such a long ramp on the Giza Plateau, nor evidence of such a massive construction. Also, a mile-long ramp would have had as great a volume as the pyramid itself, virtually doubling the man-hours needed to build the pyramid. Because the straight ramp theory just doesnt work, several pyramid experts have opted for a modified ramp theory.

This approach suggests that the ramp corkscrewed up the outside of the pyramid, much the way a mountain road spirals upward. The corkscrew ramp does away with the need for a massive mile-long one and explains why no remains of such a ramp have been found, but there is a flaw with this version of the theory. With a ramp corkscrewing up the outside of the pyramid, the corners couldnt be completed until the final stage of construction. But careful measurements of the angles at the corners would have been needed frequently to assure that the corners would meet to create a point at the top. Dieter Arnold, a renowned pyramid expert at The Metropolitan Museum of Art, comments in his definitive work, Building in Egypt: "During the whole construction period, the pyramid trunk would have been completely buried under the ramps. The surveyors could therefore not have used the four corners, edges, and foot line of the pyramid for their calculations." Thus the modified ramp theory also has a serious problem.

The second theory centers on Herodotuss machines. Until recently Egyptian farmers used a wooden, cranelike device called a shadouf to raise water from the Nile for irrigation. This device can be seen in ancient tomb paintings, so we know it was available to the pyramid builders. The idea is that hundreds of these cranes at various levels on the pyramid were used to lift the blocks. One problem with this theory is that it would involve a tremendous amount of timber and Egypt simply didnt have forests to provide the wood. Importing so much lumber would have been impractical. Large timbers for shipbuilding were imported from Lebanon, but this was a very expensive enterprise.

Perhaps an even more fatal flaw to the crane theory is that there is nowhere to place all these cranes. The pyramid blocks tend to decrease in size higher up the Great Pyramid. I climbed it dozens of times in the 1970s and 80s, when it was permitted, and toward the top, the blocks sometimes provide only 18 inches of standing room, certainly not enough space for cranes large enough to lift heavy blocks of stone. The crane theory cant explain how the blocks of the Great Pyramid were raised. So how was it done?

The Internal Ramp Theory A radical new idea has recently been presented by Jean-Pierre Houdin, a French architect who has devoted the last seven years of his life to making detailed computer models of the Great Pyramid. Using start-of-the-art 3-D software developed by Dassault Systemes, combined with an initial suggestion of Henri Houdin, his engineer father, the architect has concluded that a ramp was indeed used to raise the blocks to the top, and that the ramp still exists--inside the pyramid!

The theory suggests that for the bottom third of the pyramid, the blocks were hauled up a straight, external ramp. This ramp was far shorter than the one needed to reach the top, and was made of limestone blocks, slightly smaller than those used to build the bottom third of the pyramid.