BMCR 1999.08.09

De Franceschini on Guidobaldi and Michaelides

Marina De Franceschini

I would like to reply to Frederico Guidobaldi (et al., Sectilia Pavimenta di Vila Adriana, 1994) and to D. Michaelides’ comments (inspired by Guidobaldi’s book, and published in Bulletin Aiema 1997, 390-393) about my book on Hadrian’s Villa near Tivoli: Marina De Franceschini, Villa Adriana, Mosaici, Pavimenti, Edifici (L’Erma di Bretschneider, Rome 1991). Prof. Michaelides wrote: “it is a pity … that a work of such length … is marred by fundamental mistakes … in the observation and the methodology applied”. I cannot agree and feel compelled to respond.


Archaeologists rely on various kinds of evidence in order to understand the function of ancient buildings: architecture, pavements, decoration, building techniques, instrumentum domesticum and so on. All these elements are like the tesserae of a mosaic: by focusing on just one of them, we cannot see the whole picture. A book like Guidobaldi’s, which studies marble pavements in isolation, without taking into consideration their architectural context, is old-fashioned and follows an outdated method with an antiquarian’s outlook. This is also noted by Packer in his review of both his and my books ( JRA 11, 1998, 592): “concentrating on the villa’s marble revetments and pavements … Guidobaldi et al … are forced to neglect the character and significance if its design … and cannot consider its relationship to the surrounding architecture and landscape.” Likewise, in his review of my book ( Archeo, Jan. 1993) Sabatino Moscati pointed out that: “it is not possible to study the pavements ignoring their architectural context”.

Guidobaldi was not the first to think about a data base on Hadrian’s Villa. My book, which was published in 1991 — three years before his — started from the very same idea. But my catalogue entries are much more detailed: they list pavement and wall decoration, function of every room, building techniques, measurements expressed in roman feet, finds, and other details such as the presence of water basins or fountains, heating systems, and so on. There are also files for the rooms of the “Academy” and “Roccabruna,” two buildings that are inexplicably not included in Guidobaldi’s book, although they had pavements in opus sectile. In my book, each building is illustrated by a plan showing its building techniques and its type of pavement; numbers on the plan coincide with those of the files so that it is easy to locate a pavement on the plan. In Guidobaldi’s book, the system of letters and numbers to identify each room is very similar to mine, but opus sectile pavements have another number of their own, which is not shown on plan, so that — as Michaelides notes — “one has to go through the whole ‘repertorio schematico’ (Catalogue of Patterns) to trace the sectile floor of a given building”.

Guidobaldi’s book, in fact, does not have a detailed index, just a five-page Index Locorum. A good index is extremely important. Since it is not always possible for readers to peruse hundreds of pages to find what they need, all information should be made easy to find, otherwise even the best book would be useless. This is why I tried to be “user friendly” with thirty pages of “Repertoires” (for mosaics, for opus sectile, for mosaics in museums, and so on) and forty pages of Indices (Index of Names, Detailed index of Buildings, Index of Authors). M. Rassart Deberg acknowledged the usefulness of this procedure in her review of my book ( Latomus 1994): “a series of Indexes gives easy access to such a vast information.” J. Balty also wrote ( Antiquité Classique 1995): “The Repertoires surely make easier to find references in this excellent working instrument”.

Hundreds of files and entries — for every room of all buildings — make an imposing database. But this is a useless work if the data are not summarized and analysed at the end. This is not done in Guidobaldi’s book, as Michaelides pointed out: “It is a pity that the analysis is not taken further, bringing into discussion more recent views on the matter” (p. 391). In my book the information is analysed in a series of chapters, one for each building.

By studying the type and distribution of the pavements and wall decoration, I was able to reach new and important conclusions about the function of each building. Pavements do in fact follow a very precise hierarchy, which recurs consistently throughout the Villa and can be summarised as follows. First, there were luxury pavements: opus sectile and polychrome mosaics, with wall decoration ranging from marble to mosaic, from stucco to frescoes. This kind of decoration appears only in the main, “state” apartments, where the Emperor lived. They were monumental, had a complex architecture, scenic gardens with water basins and fountains, terraces with panoramic view, heating systems, and single latrinae — such as the “Edificio con Peschiera” (Building with Fishpond). Second, there were simple black-and-white mosaics with geometric patterns or black border stripes. Together with frescoes, they occurred only in secondary buildings, which were not monumental, were in hidden positions, had multiple latrinae and no gardens, heating system or view — such as the Hospitalia, meant for high ranking personnel like the liberti. Third, there were rough pavements, with coarse mosaics, brick or opus spicatum flooring. These appear only in buildings located out of sight, often underground, and meant just for slaves — such as the “Caserma dei Vigili” (Guard Barracks) or the “Cento Camerelle” (Hundred Chambers). To me, studying mosaics and opus sectile was the key to understanding how Villa Hadriana functioned. Cf. Packer (p. 588): “For De Franceschini, the Villa’s pavements are useful guides to the original use of the structures in which they appear”. Again Moscati in Archeo wrote: “It became evident that there was a precise relationship between types of buildings and types of pavements.” And J. Balty: “All the subtle hierarchy of Roman society, from Emperor to slave, was translated into the architecture and decoration of the Villa.”


Guidobaldi’ classification of opus sectile is not very clear. Michaelides writes: “motifs are given in code form a QqO*S8Q/R(B,Q,B)/Q which appears daunting.” I have proposed a simpler classification (pp. 682-684) with just three categories: 1) “Modulo Semplice” (Simple Module), for patterns using a single geometric figure, such as squares or triangles (even the “listellati” — striped patterns, which Guidobaldi inexplicably does not include among opus sectile pavements). 2) “Modulo Quadrato Reticolare” (Square Grid Module) (a term taken over by Guiobaldi), which employs squares, rectangles, and smaller squares. 3) “Modulo Misto” (Mixed Module), formed by two or more geometric figures, such as octagons and squares, or triangles with squares and hexagons. Their names make it easy to understand which was the pattern used: Modulo Semplice I, A1 rectangles, or Modulo Misto III, A1, squares and rectangles.


The use of measurements in Roman feet is of fundamental importance, especially when marble tiles are preserved. Guidobaldi complains about “uneven” measurements, which he rounded up to the next centimeter; he writes (pp. 68-69): “It would be illogical to give precise measurements to elements, since they vary from element to element” (sic!). If only he had used Roman feet instead of centimeters, he would have seen that opus sectile tiles correspond perfectly to dimensions in Roman feet: uneven 37.7 cm. are a round one and one-half Roman feet.

Guidobaldi devised a method for reconstructing opus sectile patterns when the tiles are missing and just their imprints in the mortar are preserved. Results seem wonderful, but Michaelides himself has some doubts: “It is sometimes difficult to see how the authors have arrived at the reconstruction of a pattern from the impressions left in the mortar — but one has to trust the keen eye … of a group of people … who has worked so much.” The best method would be photogrammetry together with computerized analysis of all preserved imprints. This none of us could do. When only impressions are left, and they are very weathered, as in the “Pretorio” or in the “Piazza d’Oro”, I preferred to write “opus sectile imprints,” instead of venturing in doubtful reconstructions. But Guidobaldi stated that I did this because I had no method, I never visited some buildings, and everything I did was “totally wrong.” I am afraid that his method of reconstruction is far too optimistic and does not rely on sound evidence. It is not enough to trace lines on high quality photographs taken with raking light: there is the risk of creating patterns that do not actually exist. A simple check applying measurements in Roman feet to the reconstructions would have easily brought out their faults, and in fact many of Guidobaldi’s drawings find no parallels in other known examples. What is worse is the fact that Guidobaldi published these reconstructions as if obtained through a proven and sound scientific method, without pointing out that they are purely hypothetical.


There are many articles and partial studies on Hadrian’s Villa, but just two complete books: one by H. Winnefeld (1895) and another by P. Gusman (1904); many pavements, especially those in opus sectile and simple black-and-white mosaics were previously unpublished. Therefore Moscati wrote of my book: “Since there was no complete work on the subject … the author catalogued all the Villa’s pavements, thus making the first systematic study “. And M. Rassart Debergh: “The great value of her work is that it studies all buildings and their decoration, in a complete and accurate monograph”. J. Balty commented: “Never before had Hadrian’s Villa been studied systematically, including all its buildings”. In the Italian newspaper Il Messaggero the (January 9th, 1992) Carandini wrote: “… this illustrious monument is studied scientifically for the first time”.

In my book, the first on the subject since 1904, I believe I have said something new, and my ideas rely on evidence that occurs consistently throughout the whole Villa. It is not obvious at all, as Guidobaldi claims, that “the distribution of pavements allows us to make some simple statements” about the function of the various buildings. Nobody had thought or written that before I did. But I was pleased to see that, three years later, my ideas about the function of the buildings were shared by Guidobaldi in his final chapter (which does not quote me even once). Again J. Balty wrote about my book: “it is an example of method, … it answers the main questions about the function of the Villa, with a synthetic analysis at all levels”.

I know well that my book may, and does, contain some mistakes; every time one goes to Villa Hadriana, one can see something new or have new ideas. But I cannot accept a second-hand unfavorable judgment, based on Guidobaldi’s assertions and not on a reading of my book. I hope that, after reading these remarks, Professor Michaelides will find time to check my work and perhaps to write a review of it.