Aut Sol Aut Umbra: Bath Orientation, Sun Position, and Mechanisms for Maximizing Solar Radiation in Pompeian Villae Rusticae (20 min)


Cristina M. Hernández, Mt. San Antonio College


Various Roman authors (e.g., Vitr., De arch. 6.4.1; Colum. Rust. 1.6.2) tell us that domestic baths (balnea) should align with the sun during specific times of the day or year to harness sunlight during common bathing hours. It has been inferred that Roman bath builders also sought to maximize access to solar radiation to augment artificial heat sources and maintain hot bath microenvironments. However, few scholars have studied bath orientations vis-à-vis solar-temporal data to understand the ancient prescriptions or interrogate the modern claim that domestic baths were oriented for solar heat.

In this paper, I borrow a method from cultural astronomy to examine the solar alignments and architectural designs of Roman domestic balnea (first century B.C.E.–first century C.E.) in 17 villas near Pompeii and particularly within the villae rusticae of Boscoreale (e.g., Villa Rustica of the Boscoreale Treasure, Villa di Palma, and Villa of N. Popidius Florus). My goal is to explore how and when bath builders sought to maximize the effects of sunlight and heat.

While my previous research has demonstrated that most Pompeian domestic balnea were oriented and designed to mitigate the effects of solar radiation during the eighth hour of summer, I demonstrate here how some household baths were oriented and designed to harness maximum solar radiation, especially during colder months of the year or morning hours.

This study shows us how Roman builders constructed baths in response to the environment and climate, allows us to better comprehend the unique ways Pompeian balnea were experienced by household bathers, and more broadly nuances our understanding of the Roman bathing habit.