The Vault of the so-called serapeum: an ellipsoidal geometry at Hadrian’s Villa

The so-called Serapeum of Villa Adriana, Tivoli, is one of the most relevant monuments of antiquity. It is the subject of several previous studies, beginning from the Renaissance. Nevertheless, a compelling description of the unique geometry of its main vault still needs to be provided. This paper reports the first novelty discovered within a study set out to develop a deeper understanding of such geometry: the use of an ellipsoid-based shape. The result is of overriding interest both within the understanding of the monument and in the general context of ancient design. The finding could shed new light on understanding the Roman Imperial age’s theoretical mastery of double-curved surfaces through its consistent applications to architectural solutions.