A Fascinating Discovery The Pantheon in Rome is one of the masterpieces of ancient Roman architecture, from an artistic point of view and for the buildin technique: it has the largest unreinforced concrete dome in the world, which was always sudied and admired. The book follows its story and explains the secrets of its construction. Most of all is focused on archeo-astronomy, showing the luminous phenomena that take place there. In the Pantheon we made our most fascinating discovery: the Arc of Light and the Square of Light which are seen only for a few days during the year and had a precise symbolic meaning.