Innovative Vaulting in the Architecture of the Roman Empire: 1st to 4th Centuries CE

Lancaster’s book is the first to deal with a variety of building techniques other than concrete used for vaulting in Roman times (first to fourth century C.E.). Her work approaches in a taxonomic way the most innovative vaults used by Roman builders, showing their evolution and distribution in different regions. In relation to her previous book (L. Lancaster, Concrete Vaulted Construction in Imperial Rome: Innovations in Context [Cambridge 2005]) the shift in focus is from Rome to the Roman provinces. The text is clear, and the intention to explain technical topics in simple and effective phrasing is successfully accomplished. She discusses structural principles, chemical processes, and construction details with equal concision. Her work is based both on published sources and personal analysis. An online catalogue contains colored figures and maps that give a visual understanding of the distribution of the vaults.

The book is not only a discussion of techniques in different periods and regions. It also investigates structural, economic, social, and aesthetic issues related to the use of a specific vaulting technique, with the purpose of understanding how and why an innovation was introduced to the building practice. Some of the topics of the book were discussed in the author’s earlier articles, but this publication draws together different aspects of vaulting techniques in a single text, thus offering a valuable reference tool to researchers (and to students).

The main focus of the book is on the different vaulting techniques: when and where they are first found, how they spread, and what variations can be traced through evidence. The result is remarkable, despite the challenges of sifting through the partial data currently available, the lack of technical information (building techniques that are undervalued or misunderstood by the excavators), or the impossibility of establishing a precise new chronology. The problematic issues are thoroughly tackled by the author in her presentation of many case studies, where she seeks to revise current interpretations and to analyze data offered in preliminary reports of other authors, as, for instance, for the great hall in Argos. One of the strengths of the book is the author’s capacity for visual observation of construction details, which are juxtaposed with available archaeological and historical data.

Lancaster's contribution to the study of Roman construction techniques is considerable, since this evidence-based study substantially increases the quality of interpretation of Roman construction in the provinces, where field archaeology has sometimes failed to understand fully the significance of regional building techniques, as in the case of pitched-brick vaulting, which can now be traced from the Near East to Greece and then to Asia Minor.

The book is organized in several sections. An introduction (ch. 1) and synthesis on Roman mortars (ch. 2, “Opus caementicium”) are offered before four different building techniques are discussed: solid brick vaults (chs. 3, 4), vaults with tubes (ch. 5), hollow voussoir vaults (ch. 6), and vaults with ribs of armchair terracotta voussoirs (ch. 7). The closing chapters are dedicated to the stability of abutments (ch. 8, “Vault Behavior and Structural Form”) and to the understanding of the relationship between the spread of a building technique and the context (ch. 9, “Vaulting Techniques in Context”).

A multitude of CAD drawings support the descriptions. They avoid superfluous graphic virtuosity and aim at a conciseness that is beneficial for the reader. The diagrams clarify the descriptions and interpretations given in the text.

It is not possible to comment here on individual chapters, but mention must be made of the main aspects relating to these innovative vaulting techniques. Solid brick vaults were typically adopted in the east, with a few interesting exceptions in imperial Rome (only marginally mentioned in the book). The author distinguishes brick barrel vaults (ch. 3) from other vault forms: squinch vaults, pavilion vaults, cross vaults, sail vaults, domes, and semidomes (ch. 4). The different forms of the vaults addressed distinct structural needs, as well as different aesthetic issues. The author analyzes the way bricks were laid, itself an important contribution to the terminology of methods of construction. She particularly underlines the importance of the introduction of brick vaulting to Asia Minor and vertical-brick vaulting in the province of Achaia in the second century C.E., since they reflect two crucial issues discussed in the book: the transfer of technology and the role of eastern elites in the spread of fired-brick construction.

The chapter dedicated to vaulting tubes (ch. 5) is based on previous scholarship but includes more recent discoveries, particularly early examples in Sicily and Catalonia (Cabrera de Mar), which are enlightening for the understanding of medium-sized vaults (ca. 5.5 m wide). Their use in thermal buildings (thus exposed to fire and moisture) leads the author to highlight the importance of baths as a driving force of new technologies.

Hollow voussoirs (ch. 6) were adopted primarily in Britannia and were used almost exclusively in thermal buildings. The analysis points to the fact that they were employed for heating purposes, but at a later stage they were adopted for structural purposes in very large vaults (as at Wroxeter, Canterbury, and Bath).

Vauting ribs of armchair voussoirs (ch. 7) were used in most of the western provinces. The text provides a synthesis of the techniques across many regions, based on published reports and observations. Closer examination of the early stages of vaulting ribs would have improved the discussion, but at present the material found in the baths of Caulonia and Fregellae is still awaiting a detailed technical study. This building technique developed in southern France and expanded to Iberia, Narbonensis, and Aquitania in the first century C.E. to suit the requirements for economic and rapid construction of vaults in small baths.

Lancaster has made yet another important contribution to scholarship with a book that will remain a fundamental source of information for future studies on Roman construction.

Paolo Vitti
Department of Architecture
Roma Tre University
vitti@tiscali.it