Construction engineers and archaeologists have not been able to agree on ways in which the Great Pyramids of Giza (and others) might have been constructed - at around 2580–2560 BC.
“The logistics involved in the construction of this pyramid are staggering when one considers that the ancient Egyptians had no pulleys, no wheels, and no iron tools.”
“The dimensions of the pyramid are extremely accurate and the site was leveled within a fraction of an inch over the entire base. This is comparable to the accuracy possible with modern construction methods and laser leveling.” Source : Civil Engineers Magazine 1999, (archived)
Also, some of the limestone and granite blocks weigh more than 20 tons, and there is no agreement about how they may have been cut and moved.
Further reading : Wikipedia