Okay, another question. Who estimated, or why was it estimated that it took between 10 and 20 years to build the great pyramid of Giza?

I forgot to mention that it was about the great pyramid of Giza. Sorry :)

From The Complete Pyramids by Mark Lehner at the Oriental Institute:

*The 10-20 year estimate seems to be based of the reign of Khufu as listed in the Turin Papyrus- a document written 1400 years later and probably not accurate. 30-32 years is probable.

*The Great Pyramid, queens' and satellite pyramids, and assoicated temple and mastabas have a volume of 2,700,00 cu. m. That's 2300 cu. m. per day. With a 10-hour work day, that comes out to be one average size block every 2-3 minutes.

*We do know that the blocks do get much smaller at the top, and that the base makes use of natural bedrock.