Who built the Pyramid of Khufu

Hanging in one of the offices where I work, there is a poster that, at first, looks like one of those motivational posters with a picture of the pyramids and the word "Vision" written below it. But the rest of the caption reads: Any vision can become reality with persistance, faith, and an unlimited supply of disposible labor." I think the truth of the matter is that Egypt had lots of vision, and lots of slaves, plus some pretty smart engineers. There have been many many instances in history where one culture has achived great scientific knowledge, only to have it be lost for centuries by later generations. Just because we don't know how the pyramid was built does not mean that a prior human could not have figured it out. If the Giza pyramid was the only pyramid we had, then sure, maybe I could be swayed by the "aliens built it" theory. Because if they (the aliens) were that advanced, they could just come down and show us how to build it perfectly the first time. But the fact is that there are hundreds of other pyramids, of lesser size and quality of construction; "practice pyramids", if you will. If humans were building a couple of these every generation, it would make sense that they would eventually figure out better and better ways to do it, it is a natural progression. Until of course, they realized that they were pouring an inordinate amount of resources into these projects and began scaling them back.

I have heard about this argument saying that these pyramids either built by aliens or the civilisation of Egypt with the help of Aliens. Now when I say Aliens I mean to define an advanced life from a different galaxy need not be one of those strange looking Hollywood characters. The book "Story of an Arabian Princes" mentions this. There is another book also which gives a step by step logical reasoning confirming the involvement of extra terrestrial intelligence. I do not recall the name, but soon will give you the name of this book.