Who were the ancient Egyptians? What did they believe? What did their art mean to them and what materials did they use to make it? We don't know everything about this culture, but we have learned quite a bit.
While today we consider the Greco-Roman period to be in the distant past, it should be noted that Cleopatra VII's reign (which ended in 30 B.C.E.) is closer to our own time than it was to that of the construction of the pyramids of Giza. It took humans nearly 4000 years to build something--anything--taller than the Great Pyramids. Contrast that span to the modern era; we get excited when a sports record lasts longer than a decade.