Looks like historians are not going to let the myth and mystique of the Sphinx survive! They are keen to demystify the origins and contruct of the spectacular structure at the earliest.
Just came across an article in the Telegraph, Uk which talks about how they have come to the conclusion that the Sphinx was probably built much earlier than the 3 pyramids at Giza, and, how the head/ face that it was originally built was one of a lion which was subsequently replaced by that of a Pharoah when the pyramids were built.
Its fascinating isn't it, how even centuries ago they were capable of building structures on a gigantic scale that would withstand the test of time...
You can read the article here