The Pantheon is lighted solely through the great hole, thirty feet across, at the top of the cupola. (The building is so large that the inconvenience from rain is negligible.) The best possible idea of the perfection of this great building is to be gained by looking down into the interior from high above, from the edge of the hole in the roof. This dizzy height, at which one may glory or despair according to the measure of one’s acrophobia, is reached by a stair behind the left apse in the porch. The stair gives access to the cornice at the top of the drum; one then walks half-way round the cornice, which is wide but unrailed, to the back of the drum, where a flight of steps, only half-railed, leads up over the lead plates (the original gilt bronze was sent to Constantinople in the seventh century), to the aperture, from which those with a head for heights can gauge the aesthetic satisfaction of realizing that the interior is exactly as high as it is wide. The total effect, massive, daring, playing with space, yet not entirely successful technically, reflects the man. One wonders what Hadrian’s tortured and cynical spirit would make of the vicissitudes his building has suffered. A Barberini pope in the seventeenth century used the bronze of the porch roof to make the canopy over the high altar of St. Peter’s, and guns for the papal fortress, Castel Sant’ Angelo (which had once been Hadrian’s mausoleum); of this vandalism the wags of 1625 made the famous epigram, “_Quod non fecerunt barbari fecerunt Barberini_,” which might be paraphrased, “The Barberini rush in where barbarians fear to tread.” At the same time Bernini added a pair of ridiculous bell towers--called “the ass’s ears”--which were not taken down until the nineteenth century. Perhaps Hadrian would be better pleased to know that men like himself were buried in his building: a great creative artist--Raphael--and two Italian kings. While the Pantheon was being built, an activity unexampled in the history of Roman architecture was going on at the villa. To the fruitful years after 125 belongs the uniquely inspired plan (Fig. 11.12) of the most important palace in the villa complex, called the _Piazza d’Oro_, the Golden Square. Its “pumpkin” vestibule (K in the plan) has already been mentioned. In many of its features, including the hole in the roof, the eight supporting piers, and the alternation of curved and rectilinear niches, it is a quarter-scale Pantheon, but there is greater frankness in the display of the structure, both internally, in the groined vault, and externally, where the octagonal plan is left clearly visible, instead of being concealed by the skin of the drum, as in the Pantheon. Except perhaps for the cross-vaulted passages N,N, the portico is conventional; excavation in the summer of 1958 revealed footings for formal flower beds, as in the portico of Pompey’s theater, and in Vespasian’s Forum of Peace.