The Basilica Ulpia, Early Christian Churches and the Roman Double Truss

A new analysis reveals that the Basilica Ulpia, a notable timber truss-roofed building from imperial Rome, likely employed a double-truss roof system similar to those found in early Christian basilicas like Old St Peter’s and San Paolo fuori le Mura. This design, documented by Jean-Baptiste Rondelet in the 18th century, was critical for distributing weight and preventing overloading of stone architraves. While James E. Packer’s 1997 reconstruction proved structurally viable, it lacked convincing evidence for the roof structure. Engineering assessments confirm that the double-truss arrangement would have been both functional and innovative, suggesting its use in early Christian architecture was a continuity from Roman practice rather than an independent development.

Robison, E. C. (2021). The Basilica Ulpia, Early Christian Churches and the Roman Double Truss. Architectural History, 64, 187–222. https://doi.org/10.1017/arh.2021.9