Fortunately, there is more to Egypt than just Cairo, but a visit to Egypt would not be complete without seeing Cairo. and Giza.
Cairo was not my favorite place to visit because of the extreme poverty and pollution, but, there is so much history to try to absorb from the thousands of years under the various pharoahs, that a brief visit to it to see the New Great Egyptian Museum (not quite open on our visit) and the pyramids, is a reason to go.