"How the Pyramids at Giza were built is one of Egypt's biggest mysteries." The Giza Pyramids, built to endure an eternity, have done just that. The monumental tombs are relics of Egypt's old Kingdom era and were constructed some 4,500 years ago. Egypt's pharaohs expected to become gods in the afterlife. To prepare for the next world they erected temples to the gods and massive pyramid tombs for themselves—filled with all the things each ruler would need to guide and sustain himself in the next world.