The study and publication of Trajan’s Column has mirrored the development of European academic studies from the 15th century to the present. Modern research may be pursued through examination of antiquarian sketches, published engravings, casts made of the reliefs at different times, published photographic coverages and, of course, study of the original monument.
Sketches and Engravings
Numerous artists and antiquarians sketched scenes from the reliefs of the Column from the later 15th century onwards, thereby circulating images which had a tremendous, widespread influence in many media (Agosti and Farinella 1988a; 1988b; Marin 1988). More systematic treatments included a set of 130 plates illustrating the Column’s frieze, published in 1576 with engravings by Francesco Villamena and text by Alfonso Chacón (Chacón 1576; Bastianetto 2001). It was dedicated to Trajan’s ‘compatriot’, the Spanish Hapsburg King, Philip II. Later editions appeared in 1585 and 1616. Pietro Santi Bartoli published the most influential set of engravings, with a commentary by Giovanni Pietro Bellori (based on Chacón’s work), in 1672. This was dedicated to King Louis XIV, “il Traiano della Francia”. Bellori’s version was also subsequently used as a basis for description (Fabretti 1683. Cf. Gori 1752).
Sketches and engravings, such as Santi Bartoli’s coverage of the Trajan’s Column frieze, or the 18th century views of the Column’s pedestal reliefs by Percier and Piranesi, inevitably incorporated some elements of contemporary artistic style, for they were not exercises in exact archaeological recording in the modern sense (Uginet 1985; Agosti and Farinella 1988b, 96-109; Wilton-Ely 1994, 743-66; Ficacci 2000). Indeed, Santi Bartoli represented the frieze horizontally rather than helically (at a diagonal across the page), and the details were given a Baroque makeover.
Despite their limitations and stylization, the Santi Bartoli engravings of the Column frieze continued to be reproduced, and to be redrawn in simplified form, even after the advent of photographic recording (e.g. Reinach 1909; Monti 1980, 69-83; Coarelli 1980, 118-27; Scheiper 1982, 158-81; Nardoni 1986, 137-74; Galinier 2007). A modern set of drawings was only published in the 21st century covering architectural structure and details, and sculptures on the pedestal and shaft. Unfortunately, due to the publisher’s inattention, only two sides of the pedestal was included in the folio (Martines 2001a, Pl. 70, 76, 87). Given the scope of such a recording project and the rarity of scaffolding access to the Column shaft, this long hiatus is perfectly understandable. The sculptures were traced on transparent film producing 1:1 drawings. Some of the latter were displayed as early as 1987 (pers. obs., exhibition The March of Rome. The Roman Soldier AD 50-150, Gloucester City Museum). The publication is invaluable for overall study, but the draughtspeople were not concerned primarily with sculptural detail, so recording of small Figure Type features was variable.
The casting of antique sculpture in plaster was a practice which took off during the Renaissance, flowered in the 17th century and continued through to the 19th century. Before the advent of photography it could provide a three-dimensional copy superior to contemporary illustrations.
Casting had the great advantage of disseminating the exact likeness widely at times when only small numbers of the interested public, rulers, aristocrats and artists, could travel freely around Europe and the Mediterranean countries. Major episodes of casting of elements of Trajan’s Column have always been patronized by French rulers. Kings François I in 1540 and Louis XIV in 1665-70 had partial cast sets made of the frieze and pedestal (Santi Bartoli was working for the latter monarch), and a complete cast of pedestal and shaft was created for Emperor Louis Napoléon III in 1861-62. All these monarchs had direct campaigning interests in Italy and Rome, and to an extent in the Rhineland, the French equivalent to the northern frontier between the Roman empire and barbaricum. Classicising rulership style and celebration of victory in war could all be inspired by the best preserved edifice honouring Rome’s optimus princeps. There had even been plans under Napoléon I for Trajan’s Column to physically join the other antique artworks looted from Napoli and Rome in Paris. Fortunately, this was never realized, the first French emperor contenting himself by having a number of monuments erected in France that were directly inspired by Trajan’s Column.
Elements of the partial casting campaign carried out for François I survive at the Palace of Fontainebleau, near Paris, and in Milan. They are now rather damaged and not very finely detailed. Some 76 cast pieces made for Louis XIV survive in the Villa Medici, Rome. Others were sent to Paris, Versailles (France) and Leiden (Netherlands), and others still were lost (Agosti and Farinella 1988a, 582-83, 591-94; 1988b, 49-53; Délivré 1988; Pinatel 1988; D’Amato 2001, 228-30). Early casts were also in circulation among artists for studio training and emulation. In the cast gallery of the Thorvaldsensmuseet in København (Denmark) there is a complete cast of Cichorius Scene LXXVIII (Victory and trophies), plus casts of one or more human heads (total 83), and some other details such as horses and military standards (pers. obs.).
Creation of a set of matrices for Napoléon III was a turning point in the study of the monument, partly because of the completeness of coverage, and vitally because of the date it was created (Froehner 1872-74, xix-xx; Agosti and Farinella 1988a, 595; D’Amato 2001, 230-33). The French dominated Rome through their backing of Pope Pius IX, restoring him to the city in 1849, and guaranteeing his independence until the French garrison departed due to the Franco-Prussian War of 1870. As soon as Rome was united with the rest of Italy it became the kingdom’s capital, at which point the sleepy papal town with its massive areas of disabitato became a major European seat of government (Caracciolo 1984; Hibbert 1985, 274-85; Petter 2000). The resultant influx of bureaucrats, rise in general population, and accompanying building boom, set the trend for increasing atmospheric pollution up to the present. Thus recording of the sculptures of Trajan’s Column through casting preserved much which has been subsequently degraded. One very finely carved feature of the helical frieze makes this abundantly clear. The zigzag chiselling on the armour of auxiliary figures is particularly vulnerable to surface erosion and comparison between casts and original Column frieze shown that 48% of the coverage disappeared between 1861-62 and March 1984 (pers. obs.). There is also noticeable deterioration by the time of the Napoléon III casts as compared with those of Louis XIV, but the rate of erosion since the early 1860s has been greatly accelerated.
The 1861-62 matrices have been used to produce various sets of casts which are extant today. One set which covers the entire frieze and one side of the pedestal went from the papal collections to the Museo della Civiltà Romana at EUR, Rome (Catalogo 1982, 594-605; D’Amato 2001, 234-36). This is displayed as separate cast sections mounted in helical progression running four times up and down the medial basement gallery which links the two wings of the museum. The casts have been cleaned and lighting improved in the gallery since the 1980s. Minute examination of the sculptures is facilitated, nose-to-nose. This is the set most used for Jon Coulston’s studies and raking torchlight was employed to check small details such as mail armour chiselling. However, all vertical and diagonal relationships between windings and Scenes are severed, and such a presentation predisposes the viewer to concentrate on ‘narrative’ progression, rather than other spatial features (just as in the main pictorial publications).
A second set which also included the whole pedestal (but not the capital block) was assembled as a column in two section in the Cast Court of the Victoria and Albert Museum (London) in 1874 (Hungerford Pollen 1874). This gives some idea of the scale of the original building, and has the three-dimensional relationships between helical windings and Scenes. Despite the fact that upper views may be taken from a balcony level, the assembled casts do not allow close examination of sculptural detail. Similar in presentation to the EUR display is the cast set in the National Museum, Bucaresti, except that pedestal has been entirely assembled as one object (Florescu 1969; D’Amato 2001, 236). The advantages and disadvantages are the same except that the oft-neglected pedestal sculptures can be fully appreciated. This was a diplomatic gift to the Romanian fascist regime from Mussolini, manufactured between 1939 and 1943, eventually moved to Bucaresti in 1967, and placed in its present gallery in 1968.
In France the casts were exhibited in 1864 in the Louvre. A section of the Column shaft was cast in bronze, covering the lowest five windings of the helix, and since 1886 it has been displayed in the fosse of the royal palace at St Germaine-en-Laye near Paris (now the Musée Nationale, see Reinach 1886). A similar section of several windings was made for the Museum für Antike Schiffahrt, Mainz (Germany) in order to display the Column’s depiction of Roman shipping (Scenes XXXII-V, LXXIX-LXXXVI mounted out of order).
Single cast sections are housed in the covered area of the Forum of Trajan libraries in Rome (CL-LV), and in the collection of the Romanian Academy, Rome (sections of LXXV, XCIII, CXIX). The basement of the Museum für Abgüsse Klassischer Kunstwerke, München (Germany), has wall-mounted casts of Scenes XXXIX, LXXII and CIV in the basement. Along with the Museo della Civiltà Romana, the V&A Cast Court and the Ashmolean Museum (Oxford, UK), this outstanding institution is one of the few research and teaching collections to survive the decline in fashion and consequent destruction of casts in the 20th century.
There are also single sections of Trajan’s Column casts in various private collections around Europe. Most recently, 16 resin casts of scenes were made in Rome for exhibition in Damascus, Syria (Calcani 2001).
The casts are vitally important for their preservation of detail and the interactive study of BOTH original sculptures and casts is indispensable. However, the latter not only limit three-dimensional appreciation of the sculptures, but the moulding process necessarily produced a matrix which could be detached from the sculpted stone. It was fortunate that the sculpture of the helix is of such low relief, nevertheless there are many examples of open hands and heavy undercutting which had to be filled in to facilitate the detachment. A good case in point is the grip of the auxiliary attendant’s sword in the Scene depicting wounded Roman soldiers (XL.20). This is carved in the round. In extremis an object might by omitted, as was a citizen soldier’s sword which formed a bridge between hand and shield, and which still survives on the original carving (CXV.14). Casting was greatly facilitated by the sculptors’ reluctance to execute such undercutting regularly, but instead they preferred to insert metal elements, especially shafted weapons. The incidence of stone weapons, standards and tools (e.g. LXVII, XCVI), as compared with provision of insert objects, presumably cast in bronze, and compared again with hand gestures which required inserts, but which were carved in such low relief that insertion was impossible (eg. XXXII), is an important feature for the study of composition, execution and the use of materials. In contrast, on the Column of Marcus Aurelius (also Carrara marble), the later sculptors executed very deep carving with shafted-weapons and other hand-held items entirely rendered in stone. Due to this very different nature of the sculptures, which also contributed to the vulnerability of, and thus heavy damage sustained by, the Marcus Column frieze, very little of that monument has been cast. Sets are limited to three windings assembled as a section of shaft in the Museo della Civiltà Romana (Catalogo 1982, 689-92), and a few scenes in the Museum für Abgüsse in München.
Photographic coverage first burst on the academic world with the publication through phototypography, daguerreotype and photogravure of the 1861-62 casts (Froehner 1872-74. Cf. Reinach 1886). Definition was not very high but enough detail was visible for study. The situation was transformed by the monumental work of Conrad Cichorius. His work consisted of two volumes of commentary (the analytical first volume never appeared) and a folio of unbound plates. The scale of the latter, again reproducing the French casts, combined with the technology of reproduction, made this the largest, highest resolution publication ever achieved (Cichorius 1896-1900). Unfortunately, the folio is very rare and only held in Britain in university libraries at Birmingham, Liverpool, Oxford (Sackler Library), University College London, University of London Senate House Libraries (ULRLS), and the Victoria and Albert Museum National Art Library.
Subsequent publications of Cichorius’ magisterial plates or of other photographs of the casts have been variable. Lehmann-Hartleben’s plates were at a much smaller scale but very clearly reproduced, serving well to illustrate the best book ever written on Trajan’s Column (Lehmann-Hartleben 1926). On the other hand Lepper and Frere chose to have the plates themselves poorly reproduced (Lepper and Frere 1988), rather than employing original negatives, as was done very successfully for the republication of Richmond’s paper on the Column (Richmond 1982). It is unlikely that any modern publisher would consider going to the expense of producing a facsimile of Cichorius’ work, especially in Britain where the book ‘industry’ has so regressed in quality and capabilities in the 21st century. However, Florescu’s publication of the Bucaresti set of casts was moderately clear and forms an accessible and useful resource (Florescu 1969. See also Silverio 1989; Depeyrot 2008; Pogorzelski 2012).
Photographic coverage of the Column frieze have been attempted at a distance using telephoto lenses, as in the worst book ever published on the subject (Rossi 1971). However, the opportunities presented by scaffolding coverage in the 1980s combined with the Internet revolution transformed publication. The volume edited by Settis contained a coverage taken and reproduced in colour, printed on high chalk content paper (Settis 1988). The images were made of the frieze before it was cleaned so show the sooty pollution deposits very clearly. To create uniform conditions the photographs were taken at night with artificial light. This had the particular virtue of clearly revealing survival of the patina on the surface of the stone, a vital element for appreciation of acid rain erosion and preservation of small details and tool marks (see also Melucco Vaccaro 1985).
Subsequent to cleaning, a black and white photographic publication appeared in tandem with the same treatment of the Column of Marcus Aurelius (Coarelli 2000; 2008). An additional stream of available images has been provided by Internet publication, notably though the archive of the Deutches Archäologisches Institut in Rome, and the McMaster Trajan Project site (see ‘Links’). The latter is based on the photographic collection of the sculptor Peter Rockwell, and further information about his work and additional resources for studying the sculpting of Trajan’s Column are available with a mass of detailed images on the project website of Art of Making in Antiquity: Stoneworking in the Roman World. The detail available is extraordinary, for example the wounded citizen soldier in Scene XL clearly has an incised thumbnail (XL.13).
Unless otherwise credited, images presented in the Trajan’s Column Online Project were taken by Jon Coulston using a range of Agfa, Fuji, Perutz and Kodak colour slide films, and Ilford black and white print film, on Pentax MV SLR and Nikon Coolpix digital cameras.
The Original Monument
There is never any substitute for studying an original monument or artwork, where possible. However, the opportunities to ‘get close and personal’ with the helical frieze of Trajan’s Column are very rare. Scaffolding was erected for restoration and the various campaigns of casting, and a photograph taken in 1861 shows multi-level, hexagonal platforms around the shaft (Coarelli 2000, 267). Concerns about air-raids during the Second World War led to the fascist regime erecting protective coverings for some monuments on Rome, and the publication of photographic studies made at the time (Romanelli 1942).
At the beginning of the 1980s there was a positive move to protect and restore many of the most prominent sites, buildings and museums in Rome. The Via dei Fori Imperiali was scheduled for closure and excavation, partly as a political revision of this fascist monument, the erstwhile Via dell’Impero (Painter 2005, 22-5). There was even an experimental ban on motor traffic on Sundays to accustom Romans to the idea. Large sums of lire were earmarked and one of the highest identified priorities was the study and prevention of acid rain erosion on marble surfaces. Consequently, much to the frustration of tourists, but to the gratitude of scholars, the 1980s and early 1990s saw many of the ancient sculpted monuments covered in scaffolding with platforms and stairways (initially access up scaffolding poles using brackets), and enshrouded with signature green plastic netting (Colonne 1976; Whitehouse 1983; Nylander 1988). Scaffolding was up for years at a time, and could sometimes itself be observed being periodically ‘restored’. These monuments included the Temples of Castor, Hadrian, Mars Ultor, Saturn, and Vespasian and Titus; the Arches of the Argentarii, Constantine, Gallienus, Severus and Titus; the Columns of Marcus Aurelius, Phocas and Trajan. Bar the occasional insurance difficulty, the Soprintendenza Archeologica di Roma liberally granted access to scholars and students (notably those attending British School at Rome Summer Schools).
For Trajan’s Column, Jon Coulston was given free access and even a set of keys was loaned for the most intense period of work in 1984. This was entirely due to the kind offices of the then Soprintendente, Adriano La Regina, and the co-operation of Arch. Giangiacomo Martines. Many visits were made in the company of the latter scholar whose knowledge of Roman architectural planning and design is unrivalled. In 1992, once the scaffolding (and its deep shade) had been removed, it was possible to study the pedestal in detail. For this work Jon Coulston was given the use of a wheeled scaffolding tower, and the assistance of Gianni Panelli for its placement. At this time, and on subsequent fieldwork visits, kind assistance and detailed discussion on sculpting aspects was also offered by Cinzia Conti.
There are major advantages of studying the original reliefs (in close conjunction with the casts). Standing on the scaffolding around the shaft gives a physical perspective which is much closer to that of the sculptors than may be achieved in a casts gallery. Thus it is easier to appreciate the scale of the project. The viewer is also much more inclined to consider the helical frieze as a three-dimensional undertaking and to observe relationships between windings and Scenes. Many vertical and diagonal relationships are revealed thereby. The most obvious example would be the two appearances of armoured Sarmatian cavalry, occurring in just two scenes, and those one above the other (Scenes XXXI, XXXVII).
Secondly, it is important to observe the surface colours of the original sculptures. There is a faun coloured patina on the stone, as distinct from the hue of the marble itself. Where this patina survives the smallest details of tool-marks and Figure Type details are retained, especially mail zigzag chiselling; where it has been eroded away the details are largely lost. The layer does not actually preserve sculptural features, so much as draw the eye to where they are not compromised. For a long time controversy has continued over the nature of this patina: natural or man-made, and, if the latter, when applied? It was thought that the layer may be a ‘scialbatura’ applied to the surface during one of the Early Modern restorations, or a ‘shelter-coat’ original to the Trajanic project, designed to tone down the glare of the marble surface (to increase legibility), or to act as a textured undercoat for a polychrome paint treatment. Partly through scientific analysis, and partly arising from the observation of similar patinas on marble outcrops and on other ancient buildings around the Mediterranean, it is now considered by many scholars to be a natural development of calcium oxalates (Del Monte and Sabbioni 1987; Del Monte et al. 1987; Zanardi 1988, 289-94; Coulston 1990, 304-6; Conti 2000, 246-48).
The question of whether or not Trajan’s Column was originally painted is a vexed one. It reflects the waning and waxing of broader studies since the Renaissance, action and reaction following on between ‘monochrome’ and ‘polychrome’ views. The latter is in the ascendant at present, related as it is also to the study of coloured marbles (Schneider 1986; Coulston 1990, 303-4; Nuccio and Ungaro 2002; Brinkmann and Wünsch 2005). There have been many claims of paint identification on Trajan’s Column, some doubtless confused with the verdigris wash from the crowning bronze statuary, and with the hues of the patina. There has also been a number reconstructions of the frieze in a painted state (Froehner 1872-74, xviii; Agosti and Farinella 1988a, 596-97; 1988b, 39-40; Del Monte et al. 1998; Pogorzelski 2012). Recent conservation studies have failed to locate any convincing examples of remaining paint (Conti 2000, 246).
Agosti, G. and Farinella, V. 1988a: ‘Nuove ricerche sulla Colonna Traiana nel Rinascimento’, in Settis 1988, 549-97
Agosti, G. and Farinella, V. 1988b: ‘Il fregio della Colonna Traiana e i Francesi’, in Francesi 1988, 19-231
Bastianetto, B. 2001: ‘Le incisioni e i disegni della Historia utriusque belli Dacici di Muziano-Ciacconio: nuovi documenti’, in Festa Farina 2001, 216-20
Brinkmann, V. and Wünsch, R. (ed.) 2005: Bunte Götter. Die Farbigkeit antiker Skulptur, Basel
Calcani, G. 2001: ‘La Colonna Traiana per Damasco’, in Festa Farina et al. 2001, 269-80
Caracciolo, A. 1984: Roma Capitale, Roma
Catalogo 1982: Museo della Civiltà Romana. Catalogo, Roma
Chacón, A. 1576: Historia utriusque belli Dacici a Traiano Caesare gesti, ex simulachris quae in columna eiusdem Romae visuntur collecta, Roma
Cichorius, C. 1896-1900: Die Reliefs der Traianssäule, Berlin, II 1896, III 1900
Coarelli, F. 1980: Guida archeologica di Roma, Roma
Coarelli, F. (ed.) 2000a: The Column of Trajan, Roma
Coarelli, F. 2000b: ‘The Column of Trajan’, in Coarelli 2000a, 1-34
Coarelli, F. 2007: Rome and Environs. An Archaeological Guide, Berkeley
Coarelli, F. 2008: The Column of Marcus Aurelius, Roma
Colonne 1976: La Colonne Trajane, les dossiers de l’archéologie 17, July-August, Dijon
Coulston, J.C.N. 1990a: ‘Three new books on Trajan’s Column’, Journal of Roman Archaeology 3, 290-309
D’Amato, C. 2001: ‘La Colonna Traiana: da simbolo ideologico a modello materiale. Manufattura e diffusione dei calchi’, in Festa Farina et al. 2001, 227-45
Délivré, J. 1988: ‘Storia materiale dei calchi della Colonna Traiana appartementi all’Accademia di Francia’, in Francesi 1988, 261-73
Del Monte, M. and Sabbioni, C. 1987: ‘A study of the patina called ‘scialbatura’ on imperial Roman marbles’, Studies in Conservation 32.3, 114-21
Del Monte, M., Sabbioni, C. and Zappia, G. 1987: ‘The origin of calcium oxalates on historical buildings, monuments and natural outcrops’, The Science of Total Environment 67, 17-39
Del Monte, M., Ausset, P. & Lefevre, R.A. 1998: ‘Traces of the colours on Trajan’s Column’, Archaeometry 40, 403-12
Depeyrot, G. 2008: Légions romaines en campagne. La colonne Trajane, Paris
Fabretti, R. 1683: De columna Traiani syntagma, Roma
Festa Farina, F., Calcani, G., Meucci, C., Conforto, M.L. and Al Azm, A.N. (ed.) 2001: Tra Damasco e Roma. L’Architettura di Apollodoro nella Cultura Classica, Roma
Ficacci, L. 2000: Giovanni Battista Piranesi. The Complete Etchings, Köln
Florescu, F.B. 1969: Die Trajanssäule, Bucaresti and Bonn
Francesi 1988: La Colonna Traiana e gli artisti francesi da Luigi XIV a Napoleone I, Roma
Froehner, W. 1872-74: La Colonne Trajane, Paris
Galinier, M. 2007: La colonne Trajane et les Forums impériaux, Collection de l’École française de Rome 382, Roma
Gori, A.F. 1752: Columna Trajana exhibens historiam utriusque Belli Dacici a Trajano Caesare Augusto gesti ab Andrea Morello adcurate delineata et in aere incisa, nova descriptione et observationibus illustrata, Amsterdam
Hibbert, C. 1985: Rome. The Biography of a City, Harmondsworth
Hungerford Pollen, J. 1874: A Description of the Trajan Column, London (reprint Boston, 2001)
Lehmann-Hartleben, K. 1926: Die Trajanssäule. Ein römisches Kunstwerk zu Beginn der Spätantike, Berlin
Lepper, F. and Frere, S. 1988: Trajan’s Column. A New Edition of the Cichorius Plates, Gloucester
Marin, L. 1988: ‘Leggibilità e visibilità della storia’, in Francesi 1988, 234-43
Melucco Vaccaro, A. (ed.), 1985: La Colonna Traiana, Archeo Dossier, Novara
Monti, P.M. 1980: La Colonna Traiana, Rome
Nardoni, D. 1986: La Colonna Ulpia Traiana, Roma
Nuccio, M. de & Ungaro, L. (ed.) 2002: I Marmi Colorati della Roma Imperiale, Venezia
Nylander, C. 1988: ‘S.O.S. for ancient monuments’, Archaeology, July/August, 54-7, 74-5
Petter, H. 2000: ‘Back to the future: archaeology and innovation in the building of Roma Capitale’, in Coulston, J. and Dodge, H. (ed.), Ancient Rome. The Archaeology of the Eternal City, Oxford, 332-53
Pinatel, C. 1988: ‘Les moulages de la Colonne Trajane à Versailles, provenant de l’Ecole des Beaux-Arts de Paris et antérieurs à 1800’, in Francesi 1988, 274-80
Pogorzelski, R. 2012: Die Traianssäule in Rom. Dokumentation eines Krieges in Farbe, Mainz
Reinach, S. 1886: La Colonne Trajane au Musée de Saint-Germain, Paris
Reinach, S. 1909: Répertoire de Reliefs Grecs et Romains I. Les Ensembles, Paris
Richmond, I.A. 1982: Trajan’s Army on Trajan’s Column, London
Romanelli, P. 1942: La Colonna Traiana: rilievi fotografici esequiti in occasionie dei lavori di protezione antiaerea, Roma
Rossi, L. 1971a: Trajan’s Column and the Dacian Wars, London
Santi Bartoli, P. 1672: Colonna Traiana, eretta dal Senato e Popolo Romano all’imperatore Traiano Augusto nel suo foro in Roma, Roma
Schneider, R.M. 1986: Bunte Barbaren. Orientalenstatuen aus farbigen Marmor in der römischen Repräsentationskunst, Worms
Scheiper, R. 1982: Bildpropaganda der römischen Kaiserzeit unter besonderer Berücksichtigung der Trajanssäule in Rom und Korrespondierender Münzen, Bonn
Settis, S. (ed.) 1988: La Colonna Traiana, Torino
Silverio, F. 1989: La Colonna Traiana, Roma
Uginet, F.C. 1985: Roma Antiqua. Envois des architectes français (1788-1924), Paris
Whitehouse, D. 1983: ‘The future of ancient Rome’, Antiquity 57, 38-44
Wilton-Ely, J. 1994: Giovanni Battista Piranesi. The Complete Etchings, II, San Francisco
Zanardi, L. 1988: ‘Evoluzione del deperimento della Colonna Traiana. Dal tempo dei calchi di Luigi XIV e Napoleone III allo stato attuale’, in Francesi 1988, 281-98