If you have already visited the Pantheon or have not yet done so, this book will guide you to discover its thousand-year history and will make you see it in a new light. It is one of the best preserved ancient Roman buildings, one of the greatest architectural masterpieces of all times. It was designed 1900 years ago to last forever, thanks to a masterful use of materials: we will discover its building secrets. Even today it has the largest non-reinforced concrete dome in the world, probably created by Apollodorus of Damascus, the most famous architect of the time. It was saved from destruction because in 609 it was donated to Pope Boniface IV and transformed into the church of Santa Maria ad Martyres. Only in this book will you discover its extraordinary luminous "special effects": the Arc and the Square of Light, which are only seen in April and September. The Arc of Light perfectly matches the masonry arch above the portal and demonstrates astonishing calculation capabilities, a few millennia before computers... The same goes for the Square of Light. This book reveals their symbolic meaning, with splendid unpublished photographs: you will truly see it in a new light. The emperor was illuminated as if by a theatrical spotlight, the Light symbolized the favorable presence of the divinity and legitimized his power. Hadrian could say to be so powerful that he even commanded the course of the Sun.