‘From early times and with considerable determination in the ea-stern regions, the Christian tradition has associated with sacred buildings the geometric and symbolic shape of the dome, considered as a plastic image of heaven, of the Kingdom of God, and consequently a privileged place which indicates, as the patriarch Ger-manus wrote, that “The Temple is heaven on earth, in heaven God lives and moves”. Just as the icon of Christ not made by the hand of man bears wit-ness to the redeeming power of His incarnation in history, so the Temple, and in particular that part of it which links earth to heaven, the dome, reproduces the structure of the universe; it is Imago mundi, omphalos. The dome is a regulating cosmic centre, a place of encounter between human beings who aspire to the totality of the infinitely great and a God who lives and moves with them. The dome is a privileged spatial image of the mysterious embrace between human beings and God, a place where human beings are locked in the fraternity of the Ecclesia. The long history of the dome can be traced starting with the cerc-tonio through the circular shapes of the ancient cults of the heroes, the dead and the gods of the underworld right up to the divine caves, the rupestral vault, the tomb. ‘The primordial being is a sphere, happy with his circular solitude”: Greek culture, with Empedocles, saw a link between astronomic and philosophic speculation. The circular shape was for the Greeks an image of happiness. This exhibition focuses its attention on the Dome of St. Peter’s in the Vatican, on the theological, symbolic and traditional reasons behind its construction and attempts to offer a key to understanding the spatial element of sacred architecture. Like the synecdo-che in literature, here the dome is presented as indicative of all the profoundest meanings of the sacred place. Among the many domes in history, that of the Vatican is symbolic of Catholic unity and represents its geographic and historic centre. The exhibition includes over fifty panels which, beginning with a number of exam-ples of domes throughout history, illustrate in particular the theme of the dome of St. Peter’s in its various symbolic, planning and constructive aspects, all within the religious and cultural context of the 16th century, before going on to consider the influence which the Vatican dome had on the architecture of the centuries to come.’