Erodoto wrote that at the Great Pyramid 1000000 people worked for 20 years who alternated every three months. A study by L. and B. Pedrini and M.Actis Pato, who made their own and developed an hypothesis described by Jean-Philippe Lauer, tried to verify this affirmation, trying to discover what technique evolution, economical and social have permitted the creation of works like the pyramids when the Egyptian technique knowledge was limited to the use of a lever and an inclined plane. Adopting the hypothesis that the blocks of limestone were put in place by spiral ramps of raw bricks, put parallel to the faces of the pyramid with a pending of 20%, the authors of the study have analyzed the phases of the construction. These ramps, 4 meters wide to let the workers and materials transit and with a difference in level of 5 m from each other, are in the maximum number at the base of the pyramid and, as this grows, the space available is less so, to keep the specified distance, some ramps have to be interrupted: from the initial 32 ramps they pass to 16, 8, 4, in the successive phases of the construction. The masses of limestone came from the quarries on the place so an average movement of 700-800 m has been calculated, while the coefficient of the friction between the transport sleds and the ground is 0,5, a coefficient that demands the work of 60 persons to transport a block 2500 KG heavy on the plane and of 100 workers on the ramps. The distance between the two successive masses on the ramps is of 50 m and, when the ramp is interrupted for the lack of room, it is immediately demolished and the free façade is covered. For the cutting and the finishing touch of the blocks by the diggers and the stone-cutters a speed of 0,025 mq to the hour has been calculated. These hypothesis allow to calculate the duration of every phase of the construction and the number of workers present in each phase, which varies from 33000 to 52000. In a second hypothesis that considers the transport of the masses to a speed of 500 m a day and the length of the construction in 23 years (290 working days for a worker each year, considering an absenteeism of 10%) the authors have results that confirm the maximum number of “direct” workers, that’s over 51000. Besides these, we have to consider the presence of “indirect” workers (that cared for the maintenance of the ramps and of the utensils and for the programming and control of the work), that, according to later sources, were indicated in the report of 2 on 10 direct, so around 10.000 and, so with those assigned to the provisioning and to the hygienic service (only for the transport of water, some sources indicate one for every 7 workers) other 10000 people can be calculated. Considering, finally, the workers assigned to the construction and the bureaucrats active in the construction complex, it results that for 23 years more than 90000 people have worked on Cheope’s pyramid, confirming what Erodoto had said.