• 1 This article stems from the Çukurbağ Archaeological Project, a large ongoing project conducted with (...)
• 2 Previous publications include Şare Ağtürk, 2015, 2017 and 2018.

1Ancient Nicomedia, once the capital of the eastern Roman Empire with its magnificent urban landscape, now lies just below the industrial city of İzmit in Turkey. This article offers the preliminary results of the initial polychromy research on a series of painted marble reliefs from a monumental Imperial complex recently discovered in Çukurbağ district, at the heart of modern İzmit1. The complex dates from late 3rd century and its reliefs form a frieze with an astonishing combination of imperial and mythological depictions2. The importance of this discovery is hard to overstate. The later Roman Empire in the east, more specifically, emperor Diocletian’s imperial seat in Nicomedia, has now a defining monument. The depictions on the Nicomedia frieze shed light on the socio-political circumstances and their reflection in later Roman state art. Furthermore, the reliefs, as the only surviving examples of Roman relief sculpture with extensively preserved paint, elucidate aspects of ancient sculptural polychromy in this period of increased color-coding and color-symbolism in imperial iconography. Below, a brief historical overview of ancient Nicomedia and the recent archaeological investigation in Çukurbağ will be followed by a discussion of our initial investigation of the polychromy of the frieze based on multispectral imaging, microscopy, and in situ p-XRF (portable X-ray fluorescence spectroscopy).

• 3 For early scholarship and earlier archaeological investigations, see Şare Ağtürk, 2018, p. 414-415.

2Strategically located between west and east, Nicomedia, along with its protected harbor in the Propontis, was a major naval, industrial, and trade center throughout Antiquity despite numerous devastating earthquakes. According to Strabo (Geographica 12.4.2), the city was founded in 264 B.C. by Nicomedes I and became the leading city of the Hellenistic kingdom of Bithynia. In 74 B.C., it was designated the capital of the Roman province of Bithynia, and, after the ascent of Diocletian to the imperial throne in 284 A.D., it became the capital of the eastern Roman empire. The city seems to have reached its peak from then until the transfer of the imperial capital to Constantinople in 330 A.D. The catastrophic earthquakes of 358 and 386 A.D. severely damaged the city and subsequent earthquakes, in the Medieval period, diminished its significance, but it maintained its role as a major regional urban center up till today. The large size and impressive structures of ancient Nicomedia, especially during the late 3rd and early 4th centuries, were described in many Roman literary sources. Lactantius, a resident of the city during Diocletian’s rule, refers to Diocletian’s exhaustive building activity as part of his attempt to transform Nicomedia into “a rival of Rome” (De mortibus persecutorum 7.8, 10). Also, Libanius in his lament to Nicomedia after the mid 4th century earthquakes offers a detailed account of how Nicomedia’s magnificent urban structures perished in the earthquakes (Oration 61.15-17). Because the ancient city lies directly underneath the modern town, Nicomedia has never been systematically excavated. Thus, the imperial complex and the painted frieze it once adorned form the most concrete archaeological data found about this celebrated ancient city3.

• 4 The result of this initial excavation is published by in Zeyrek, Özbay, 2006.

3The first reliefs and architectural elements from Çukurbağ were recovered during rescue excavations conducted by the Kocaeli Museum in 20014. Excavators salvaged parts of approximately 11 relief panels with notable amounts of color. In 2009, two months of expansive rescue excavations revealed a large area, measuring approximately 400 m², about 22 metres above the sea level, of a large building complex and a large corpus of reliefs with painting. The reliefs, many of which retained significant remains of color, were transferred to the Kocaeli Museum, while architectural finds were stacked on top of one another and left on site. Due to ongoing legal investigations into the smuggling of some reliefs during the 2009 salvage expedition, the relief sculptures were kept in boxes and were never properly studied until the start of Çukurbağ Archaeological Project.

• 5 For the thematic program of the frieze, see Şare Ağtürk (forthcoming).

4The new archaeological project started in 2013 and was funded in 2015 by TÜBİTAK. The main purpose of this project is to analyze the sculptural and architectural finds as a whole and to identify the complex to which they once belonged. As of now, the catalogued Çukurbağ finds include 66 large fragments of architectural relief panels, all made of medium to coarse-grained white marble with grey-blue banding, presumably from Proconnesos (fig. 1 to 7). At least 20 of these slabs are fully preserved, with an average height of 1.0 metre; other finds include 129 smaller fragments of relief panels, 62 fragments of freestanding statues (from colossal to smaller than life-sized), and dozens of architectural elements, including an opus sectile floor, columns, capitals, and cornice and architrave blocks. The sumptuous variety of marble is also worth noting. Based on archaeological study and macroscopic geological examination, this includes: three sizes of Corinthian capitals of Proconnesian marble, two sizes of Aeolian granite columns, cipollino columns from Euboea that are close in size to the smaller granite columns, small pavonazzetto columns from Docimium that perhaps originally supported small-scale Proconnesian pediments of the aedicules, and large cornice and architrave blocks of Proconnesian marble. The variety of marbles is also reflected in the opus sectile floor. A new excavation of the southern part of the building initiated in 2016 revealed monumental stairs leading to the complex which the sculpture and the architectural elements had belonged. The initial examination of the architectural elements indicates that the continuous frieze mostly decorated the entablature of an aediculated hall with at least two stories. The reliefs depict Roman military expeditions, imperial rulers and soldiers in battle with barbarians, processions and religious ceremonies, as well as mythological narratives, agonistic games, and theatrical performances. The combination of such themes in one monumental structure with an opus sectile floor suggests that what we have is a hall of imperial cult, part of a much larger imperial complex, which might have initially functioned to glorify the triumph of Diocletianic rule in Nicomedia5. The archaeological evidence shows that the complex came down all at once while still in use, perhaps with the major earthquake in 358. The well-preservation of the color on the late 3rd century frieze may in significant part be due to its short life of exposure in the hall.

• 6 Examples: Del Monte, Ausset, Lefevre, 1998; Rossini, 2009; Fine, Schertz, Heinrich, Sanders (forthc (...)
• 7 See F. Wickhoff’s pioneering and searching description of the Arch of Titus in such terms: 1910, 76 (...)

5The painting preserved on the marble reliefs from Nicomedia is unprecedented in the large corpus of Roman state relief sculpture. No other state monument preserves such extensive applied polychromy, including those from Rome itself, and other reported remains of color are vestigial6. The ancient practice of painting marble state relief has not been in doubt since the 19th century (unlike the extensive debates regarding the existence and extent of color on freestanding marble statuary), and the pictorial effects employed in the carving of such reliefs, such as drilled outline techniques, chiaroscuro carving methods, and “coloring by shadows” have long been integral to their study7. The exceptional color of the Nicomedia reliefs affords an opportunity to examine state relief in color and to reconstruct this coloration in context within a defined architectural environment. It is most fortuitous that this preserved polychromy heralds from a historical period when color was increasingly emphasized in imperial costume and imagery, and when particular colors, including purple, had heightened social, political and material associations.

• 8 On background color, most recently, informed: Liverani, 2018, p. 379-385; speculative: Pogorzelski, (...)
• 9 The Luxor Temple wall paintings, especially the apse with the figures of the Tetrarchs, is a key ov (...)

7It is notable that there is no evidence for the application of color to the background of the sculpted reliefs, although background colors, particularly blue, have often been postulated (based on limited evidence) for many Roman state monuments8. The absence of background color on Nicomedia reliefs highlights how the use of color and variations of color were central to the definition, legibility, and reception of the reliefs, as well as the visual hierarchy of the reliefs’ diverse subjects and themes. The approach at Nicomedia is notably different from the extensive use of contrasting background colors (including blue) to differentiate subjects and hierarchy in the contemporaneous Tetrarchic imperial wall paintings at Luxor Temple in Egypt9.

• 10 Recent detailed discussion, see Şare Ağtürk, 2018.

9The painting appears to have been applied directly on the marble surface and is large-scale, characterized by the efficient use of large brushes to cover significant areas of color. Extensive legible brush strokes remain in the painting, which often extends adjacent to and beyond the drilled outlines of the sculpted relief. The painting technique is consistent with reliefs that were not intended to be viewed intimately. Paint drip lines indicate that the painting was applied when the reliefs were vertically oriented, undoubtedly after they were securely positioned within their architectural surround. Such drip lines are especially prominent on reliefs with imperial subjects where the thickly applied and distinctive deep reddish paint of their purple garments (chlamydes and paludamenta) ran in drip lines over the front edge of the relief blocks, such as on the recently published adventus panel depicting the meeting of the diarchs Diocletian and Maximian10 (fig. 7, center bottom).

• 11 Hekster, 2015, p. 277-287.

15Some of the best-preserved painting is on a prominent narrative focus of the reliefs – the astonishing adventus scene of emperors embracing, representing the culminating moment of an imperial procession (fig. 1, 7, 8 a). Nikai, their sculpted blue-painted wings still preserved on the background relief, flank the central embracing emperors, both of whom appear to have been similarly awash in purple, composed in the manner previously described. Having both descended from their flanking purple chariots, for all of their similitudo, they are clearly and emphatically differentiated, not only in their standing height and the height of their flying Nikai, but also, conspicuously, in their hair color (fig. 8 a): the taller, elder greeting emperor at left (Diocletian) has a light gray brown color, while the emperor at right (Maximian) has a remarkably different red hue. In preliminary p-XRF, the hair on both portrait heads displays traces of iron, lead, and copper, but with significantly more iron in the hair at left and more lead at right. VIL imaging suggests how different these paint layers are in the very different use of Egyptian blue (fig. 8 b). While no Egyptian blue appears to be preserved from flesh tones in general, microscopic examination paired with examination in ultraviolet light may suggest the partial preservation of flesh tones in these areas (fig. 8 c). This relief with its remaining polychromy has much to add to our understanding of the much-discussed similitudo, fraternitas, and aequalitas of Tetrarchic imagery11.