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Down to the time when Rhampsinitos was king, they told me there was in Egypt nothing but orderly rule, and Egypt prospered greatly; but after him Cheops became king over them and brought them to every kind of evil: for he shut up all the temples, and having first kept them from sacrificing there, he then bade all the Egyptians work for him. So some were appointed to draw stones from the stone-quarries in the Arabian mountains to the Nile, and others he ordered to receive the stones after they had been carried over the river in boats, and to draw them to those which are called the Libyan mountains; and they worked by a hundred thousand men at a time, for each three months continually. Of this oppression there passed ten years while the causeway was made by which they drew the stones, which causeway they built, and it is a work not much less, as it appears to me, than the pyramid; for the length of it is five furlongs and the breadth ten fathoms and the height, where it is highest, eight fathoms, and it is made of stone smoothed and with figures carved upon it. For this, they said, the ten years were spent, and for the underground chambers on the hill upon which the pyramids stand, which he caused to be made as sepulchral chambers for himself in an island, having conducted thither a channel from the Nile. For the making of the pyramid itself there passed a period of twenty years; and the pyramid is square, each side measuring eight hundred feet, and the height of it is the same. It is built of stone smoothed and fitted together in the most perfect manner, not one of the stones being less than thirty feet in length.

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...Herodotus mentions only to have been an hundred thousands [workers]; though both of them concur, and (m) Pliny with them both [along with Diodorus], that twenty years were spent building the pyramid.