For years scholars have believed that the pyramid of King Khufu, largest of the three "great" pyramids at Giza, had been plundered in antiquity and everything of value, including the body of Khufu himself, had been removed. Now, Zahi Hawass, the secretary general of Egypt's Supreme Council of Antiquities and director of the Giza Plateau, suspects that might not be the case. "I really personally believe," he recently told a sold-out lecture hall in the University of Pennsylvania's Museum of Archaeology and Anthropology in Philadelphia, "that the secret chamber of Khufu is hidden inside the pyramid." What changed his mind was the discovery of a set of previously unknown doors, hidden in the shafts of the so-called "queen's chamber" of the Great Pyramid. Located beneath the "grand gallery," the queen's chamber never housed a queen, and in fact, its exact purpose remains unknown. There is some speculation that it was an abandoned burial chamber, or possibly held offerings for the deceased. In 1872 an archaeologist named Waynmann Dixon discovered a pair of what were thought to be ventilation shafts in this chamber hidden behind concealed stones. They were about 20 centimeters square and remained largely unexplored until 1993 when Rudolf Gantenbrink, an archaeologist with the German Archaeological Institute in Cairo, sent a robot up the south shaft.