The Thermae Agrippae: A Reevaluation of the Modern Reconstruction

Abstract

This paper re-evaluates the interpretation of the extant remains of the Thermae Agrippae and reconsiders the phasing of the building, focusing especially on the first phase designed by Marcus Agrippa. It argues that the rotunda known as the Arco della Ciambella is not part of the original construction but a later addition from the fourth century CE. This paper also revisits reconstructions by C. Hülsen and Luisa Migliorati (2015) demonstrating how new evidence can improve their models. Notably, ancient authors who describe earlier phases of the building do not mention a dome; Pliny the Elder refers to the frigidarium’s ceiling as a camara, indicating a vaulted structure rather than a dome. Some scholars have identified the Arco della Ciambella as part of an entryway to the social center of the first phase of the complex, yet this feature is also conspicuously absent in historical accounts. Through an analysis of archaeological features and digital mapping, this paper reassesses the layout of public buildings in the Campus Martius and examines the renovations made over time. The study incorporates measurements of contemporary bathhouses, as well as comparative measurements of the Arco della Ciambella and other Augustan era domes. By realigning this evidence, this paper will contribute to a deeper understanding of the Thermae Agrippae and provides a foundation for future scholarship.