Symmetria, Mensuris and Domed Architectures in Hadrian’s Time

Recent decades have seen a renewed academic interest addressed to the study of centric-plan architectures covered with complex domes ‒ built during the period of the High Roman Empire ‒ thanks to new philological discoveries. In part, this trend is motivated by the dissemination of studies developed in recent years with digital documentation technologies, which have provided new information to understand the original shape, as well as the constructive and structural principles of many of these buildings. However, to understand the true novel features of these architectures, developed between the I and the II century AD, it is necessary to go beyond the simple use of new digital technologies for the documentation of architectural heritage by implementing a new method. This paper presents an interdisciplinary research approach (architecture, mathematics, archaeology, philology) that aims to understand how the three “species dispositionis”, or “dispositio” (τάξις), “ordinatio”, and “distributio” (oikonomía) were integrated to achieve a consistent and proper architecture with the required qualities (in particular, “symmetria”) in the construction of domed buildings erected in that temporal context. To that end, in the paper we compare buildings, besides Vitruvius’s one, also with the teachings by the Greek mathematician Hero of Alexandria and traces the application of his dimensional calculation formulae in the unique structures of Hadrian’s Villa, recently surveyed with advanced digital technology.