Dr. Earlyne Chaney, in an article titled ‘Odyssey Into Egypt, in her occult-oriented magazine Voice of Astara (May, 1982) tells of a discovery she and researcher Bill Cox was shown in Egypt. These were two tunnels, neither of which had been fully explored. One was in the temple of Edfu between Luxor and Cairo in the ruins of El Tuna Gabel; and the other near Zozer’s Step Pyramid at Cairo near Memphis-Saqqarah, within the tomb of the Bull, called “Serapium“.
Ref: Egypt's Underground Bases: http://www.subterraneanbases.com/2012/11/egypts-underground/