Cairo makes an excellent base for day trips, and the greatest of them all is barely an hour away. Giza, the western half of greater Cairo across the Nile, holds the last surviving Wonder of the ancient world — the three Great Pyramids and the Sphinx on their desert plateau — along with the new Grand Egyptian Museum, the largest archaeological museum on earth. Go early, before the tour buses and the camel touts, and give it at least half a day.
For something older and quieter, head 30 km south to Saqqara, the necropolis of ancient Memphis. The Step Pyramid of Djoser here predates Giza by a century, and the painted tombs of the nobles are among the finest in Egypt. It combines easily with the open-air ruins of Memphis and the pyramid fields of Dahshur into a single half-day outing.
Further afield, Alexandria is three hours by train and worth an overnight for its Mediterranean light and Greco-Roman past. The desert oases — Siwa, Bahariya, Farafra — require more time but are reachable with a rental car or organized tour from the city.