BMCR 1998.11.41

The Baths of Caracalla: A study in the design, construction, and economics of large-scale building projects in imperial Rome


In the long tradition of studies on Roman construction, scholars have tended to focus on finished buildings and on cataloguing the details of finished buildings. Rarely has attention been paid to the preparatory stages involved in the creation of specific buildings. Questions about the organization of the work-force or the logistics necessary for large-scale construction either have been overlooked entirely or quickly dismissed. Considerations of the building industry based on epigraphic and literary sources have helped us understand the role of architects, contractors, and the collegia, but a substantial overview of the building industry along with a complete treatment of constructional problems in Roman architecture has been lacking. It was clearly a much “safer” scholarly business to stay away from theoretical issues and simply count (or taste) the tufa blocks.

Janet DeLaine’s publication of the Baths of Caracalla has now addressed these concerns — and not with some wild voyage into uncharted theoretical time and space. Her study of the Baths carefully builds on the work of earlier scholars (with notes that are impressively thorough), but at the same time she breaks completely new ground. Given the shrewd analytical and classificatory schemes DeLaine devised for the documentation of such a wide variety of evidence, we can easily understand why such a volume has been a long time in coming.

DeLaine has established an international reputation for her work on Roman baths even before the appearance of this new volume, in particular as editor of Balnearia, a newsletter of scholarly observations and reports from the world of Roman bathing. Originally, when DeLaine began to work on the Baths of Caracalla in 1981 for a doctoral dissertation at the University of Adelaide, she envisioned a study of large-scale construction in imperial Rome and of the Roman building industry. Her detailed quantitative analysis of construction problems in the Baths of Caracalla was in many ways quite incidental to her larger aims. She gives much credit to John Humphrey, editor of the Journal of Roman Archaeology, for encouraging her to publish her work largely “as it stood” for the benefit of us all. Her approach (site specific with broader implications) is so novel that we can be grateful she allowed herself to be convinced not to wait longer.

The book is divided into five sections: an introduction, a history of the Baths of Caracalla (Part I 1), details of DeLaine’s so-called “generating processes” that created the Baths (Part II 2-7), the social and economic implications of the Baths of Caracalla for Severan Rome (Part III 8-9), and a conclusion. There are five appendices: 1) documentation with tables of major dimensions for the rooms of the Baths; 2) brickstamps; 3) architectural orders; 4) sculpture; and 5) a table of “labor constants” including types of jobs, time involved, and whether skilled or unskilled workers were needed. The volume is attractively produced with an ample supply of generally excellent black-and-white photos for every aspect of the building and its decor.

DeLaine notes in her introduction (p. 10) that while the geographical sources of raw building materials for Rome and its surroundings have been carefully identified, the problems of the supply and organization of these same materials have only been studied where there is an existing epigraphic record (for bricks and marble, e.g.). Building materials such as lime and wood for scaffolding, both required in massive quantities in any major construction program, have been discussed only in the most general terms.

By starting (Part I 1) with a detailed survey and reconstruction of the building itself, DeLaine pursues two main objectives for her volume. The first, treated in Part II 2-7, is to reconstruct what she calls the three “generating processes” of the Baths of Caracalla (design, construction, and the supply of building materials) in order to understand better the choices faced by architects and builders in matters of design and decoration, methods of construction, and the selection of raw materials. Her second objective (Part III 8-9) is to place the Baths of Caracalla (and the act of large-scale imperial building in the heart of Rome) in a wider context. She investigates the numbers and types of workers (skilled and unskilled in various trades), general organization of labor, and the estimated cost of building the Baths in relation to other imperial spending. Some comment on her success is warranted.

DeLaine explains that she chose the Baths of Caracalla as her focus for several reasons. First, even though the original magnificence of its colorful decorations and lavish appointments has been long lost, the basic structure is in a fine state of preservation. Furthermore, the Baths of Caracalla are accepted as one of the major achievements of Roman architecture, and so should represent the most sophisticated building technology available at any single moment of Roman history. It appears, in fact, that the Baths of Caracalla were the first building of this type ( thermae) on this scale to be brought to successful completion for over a hundred years in the city (p.13). Finally, both the design and the construction of the Baths were not particularly innovative or eccentric. The decision to build in an area so far removed from the traditional center of the city (Regio XII south of the Aventine and west of the Via Appia outside the Porta Capena) provided a new cultural focus. It should also be noted that the Baths of Caracalla are the only building in Rome clearly associated with that emperor.

The building history of the Baths of Caracalla in DeLaine’s hands (Part I 1) is not merely descriptive. She provides a lucid and subtle account of the building’s date of construction, the aqueduct which served it, and the original plan and decoration. Discussion of the Baths in later antiquity (p. 37) and in the Middle Ages (p. 40), and the history of the excavations up to the very recent use of the Baths as the summer home for the Rome Opera company, are also included.

In Part II 2 DeLaine uncovers the basic design of the Baths of Caracalla by thinking through the building in reverse order. DeLaine convinces us that the complexity of the central block of the Baths in both plan and elevation presupposes a detailed design process (p. 45). The symmetry of the design about the short axis provides the means of cross-checking any hypothesis about the design process and also exposes any major errors in the course of construction. The ground plan (presented in rough outline in Fig. 31) is analyzed in such a way that the scheme for completing the actual building unfolds before us. Among the series of fascinating details of the design process, including a discussion of designing the outer precinct, we learn (p. 53) that the general outline of the building has been achieved using only a single standard unit of 100 Roman feet, and that the remaining dimensions were derived from this geometrically. The remainder of section II 2 on design documents thoroughly wall thicknesses and their proportions, room heights, spacing between columnar screens, design rationale for the frigidarium, size of doors and niches, and the overall visual effect of the design of spaces. While DeLaine wisely acknowledges that she can not determine conclusively the architect’s “rules of thumb” for determining the depth of foundations and substructures in the Baths, she is able to hypothesize, not unreasonably, that simple patterns for such rules did exist. For example, she finds that the depth of the substructures is roughly 27 feet, which is also the distance between the bonding courses in the superstructure and serves as well as a module frequently used for door and window heights, as well as vault springings (p. 66).

Her revelation of such details may at first seem excessive, but they actually draw our attention once again to the connection between design and construction. DeLaine’s careful review of the Baths of Caracalla has confirmed, with very specific points of reference, the natural conservatism of ancient builders. Her analyses also focus our attention on the necessary communication between architect and builder. Architects and builders must have discussed both designs and the possible solutions to problems that occurred during construction. Mistakes must have required consultation and co-operation between architect and builder. As DeLaine points out (p. 67), since we are constrained to work only with projects which were realized, we must consider design always in the context of construction, which she herself does most effectively.

Part II 3, which details the decoration of the Baths of Caracalla, including structure and articulation, color and pattern, hierarchy and distribution, and theatrical effects, includes (pp. 77-78) a philological investigation into the meaning of the phrase, ” thermae magnificentissimae,” coined by the author of the life of Septimius Severus in the HA ( Sev. 21.11-12) to describe the Baths of Caracalla. DeLaine makes a good case here for its possible connection with the concept of magnificentia (cf. Vitruvius 6.8.9), great public architecture through which “the very stones speak.” For example, the porphyry columns leading to the natatio reinforce the image of the overseas conquest and empire also conjured up by the lavish use of imperial marbles on the floors and walls. The gilded bronze ceiling of the caldarium, also well suited to the concept of magnificentia, was an appropriate “crown” to the most important room in the bathing circuit (p. 78). In other words, while the iconographical program of sculptural decoration in the interior clearly manipulated the public’s response to the Baths, DeLaine also links the choice of materials and the nature of specific elements in the overall decorative design to the concept of magnificentia, so that all the decoration of the central block emerges as an essay in imperial power. Thus the ordinary mortal could experience, “however fleetingly … the life of the rich and powerful” (p. 84) merely by a single visit to the Baths.

The section dealing with building supplies (Part II 4) examines the question of the availability of particular materials used in the Baths: locally quarried materials, lime, brick, timber, baskets and rope, marble, metals, and modes of transport. The nature of the production processes, and the scale of the problem of supplying the project with its main building and decorative materials are dealt with in Part II 5. The small percentage of the building’s total volume that is comprised of brick may be a surprise for those who think of Roman imperial construction as being predominantly brick (p. 130). DeLaine shows that where demands of magnificentia come into play, economic arguments seem to be left behind. Her figures for iron and marble confirm this. Furthermore, in Part II 6, on the techniques and processes of construction, DeLaine demonstrates that while iron is used in highly sophisticated construction processes, much of it was not strictly necessary to the successful completion of the structure. Her close scrutiny of construction details (including preliminaries such as the access road and the aqueduct; foundations and substructures; the walls of the central block; the vaults of the central block; and the sequence of construction in the central block) offers new insights into the nature and function of common building techniques such as bonding courses and relieving arches.

DeLaine thus lays out the steps necessary to build the Baths from the initial organization of the site to the decentering of the great vaults, and all of this serves as groundwork for quantifying these actions in Part II 7: the manpower and logistics of the construction. She considers the manpower requirements for terracing, foundations, substructure, central block construction and decoration, marble floors, marble wall veneer, mosaic floors, wall and vault mosaics, wall and vault stuccos. She also explores options for the scheduling of the work, i.e., the order of work: terraces, foundations, cisterns, substructures, central block, finishing and decoration, equipment, maintenance, and administration. By way of complicated calculations, she concludes (p. 193) that the Baths of Caracalla could have supported an average minimum work-force, over the fours years of the main construction period, of 7,200 men directly involved in producing materials and construction, plus 1,800 men and an equal number of pairs of oxen for transport, with some variation upwards in peak periods. Her highest figure, which is for the year 213, is a work-force of 13,100 (p. 193). There are a few historical parallels from other periods, but all of this still implies an extraordinary power to control human resources.

Because each chapter takes on quite specific problems, which build upon each other, the reader is effectively drawn through DeLaine’s study with a gentle and helping hand. Her major contribution, surely a scholarly first in Roman architecture, is to treat problems of design, construction, and the supply of raw materials very thoroughly for a single structure, in order to explore the “wide social, economic, and political implications of large-scale public construction in the imperial capital” (p. 9) during the Severan period. The realization of this promise comes in Part III 8-9. In III 8 DeLaine attempts to come to terms with the building industry of Severan Rome. While she openly admits to having made a certain number of assumptions in order to move from quantities of materials to quantities of labor, the figures she has proposed are not mere guesswork. For one thing, they are far more detailed, given the hard data gleaned from the particulars of her quantitative analysis of the Baths, than any figures handed down in the literary or epigraphic sources. Similar data will now be extrapolated from other known building projects — in the reign of Caracalla and in other periods. This prospect is most promising. DeLaine suggests the existence of established procedures for both the design and the organization of construction in such a project. She argues that most of the labor for both construction and the production of materials was employed through the contract system. This, in turn, leads to a discussion of the new possibilities for extending patronage that such a building project would afford. For the highest levels of Roman society down through the lowest, the Baths also provided ample opportunity of reaping significant economic benefits (p. 205).

DeLaine attempts to establish in Part III 9, as far as she can, the overall cost of the Baths of Caracalla. Well aware of the serious problems of cost analysis applied to the Roman economy (p. 207), DeLaine nevertheless grapples with estimating the expenditures on the Baths, including materials, construction, finishing and decoration, and the road and aqueduct. Expressing costs in kastrenses modii (KM) of wheat, valued at 100 denarii per single KM in the Price Edict of Diocletian, her estimated total expense for the Baths is c. 12 million KM. She is not afraid to include many caveats (“the long, sometimes tortuous, and potentially unstable path we have had to follow” p. 224), but her end result does fit well with what little is known about imperial finances. Not only was the construction program a form of largesse on the same scale as imperial congiaria (p. 224), but the finished building was a permanent reminder of the power of the emperor to command resources. The Baths of Caracalla would have been a lucrative investment for the imperial court.

There is little with which to find fault. It is unfortunate, however, that he book lacks a List of Figures, a bibliography (always welcome despite the full citations in the notes), and especially an index. On the other hand, the volume is virtually free of typographical infelicities.

Without a doubt, DeLaine’s volume proves that study of the developmental stages of a specific building can shed much light on the quantitative and qualitative analysis of the remains. DeLaine’s book is altogether welcome. It is an up-to-date handbook and guide to one of Rome’s premier archaeological monuments, a scientific sourcebook for problem-solving techniques in ancient architecture, and it offers essential reading for anyone interested in the building industry and economics of ancient Rome.

Cf. M. E. Blake, Ancient Roman construction in Italy from the prehistoric period to Augustus (Washington 1947), Roman construction in Italy from Tiberius through the Flavians (Washington 1959), and Roman construction in Italy from Nerva through the Antonines (Philadelphia 1973); E. B. Van Deman, “Methods of determining the date of Roman concrete monuments,” AJA 16 (1912) 230-51 and 387-432; G. Lugli, La tecnica edilizia romana con particolare riguardo a Roma e Lazio (Rome 1957); and more recently, T. L. Heres, Paries. A proposal for a dating system of late-antique masonry structures in Roma and Ostia (Amsterdam 1983). Cf. F. Coarelli, “La riscoperta del sepolcro degli Haterii: una base con dedica a Silvano,” in Studies in classical art and archaeology: a tribute to P. H. von Blanckenhagen (New York 1997) 255-69; and S. D. Martin, The Roman jurists and the organisation of private building in the Late Republic: an attempt to date them from their materials ( MAAR III, 1924). Balnearia is the newsletter of the International Association for the Study of Ancient Baths. Cf. also J. DeLaine, “The ‘cella solearis’ of the Baths of Caracalla in Rome: a reappraisal,” PBSR 62 (1987) 147-156. For a new study of the brick industry, see M. Steinby, “L’organizzazione produttiva del laterizi: un modello interpretativo,” in W. V. Harris (ed.), The inscribed economy ( JRA Suppl. 6, 1993) 139-44. Marble is well treated by H. Dodge, “Ancient marble studies: recent research,” JRA 4 (1991) 28-50 and J. C. Fant, “Ideology, gift and trade: a distribution model for the Roman imperial marbles,” in The inscribed economy 145-70. We must turn all the way back to the Baths of Trajan to find the nearest forerunner of the Baths of Caracalla. Cf. DeLaine Part I 1, 13, note 2. Cf. DeLaine, Part I 1, 13, note 1 and RE II (1896) 2434-2453. As of the summer of 1997 the grand sculptures (Farnese collection) from the Baths of Caracalla which are in the Museo Archeologico Nazionale of Naples, had been newly cleaned and arranged with splendid descriptions and up-to-date discussion of their placement in their original settings. DeLaine (p. 194) compares the recorded figures for men working on the dome of St. Peter’s in Rome in 1588. A cottage industry of new studies, patterning themselves after DeLaine, has already started to emerge. Cf. most recently, Lynne Lancaster, “Building Trajan’s Markets,” AJA 102 (1998) 283-308.