Fieldwork in late 2012 and early 2013 saw a resumption of work on the Palazzo Imperiale for the first time since 2009. This is a 2 ha structure that is located upon an isthmus at the centre of the port, affording its occupants very clear views over the Trajanic and Claudian basins (Keay, Earl and Felici, 2011). This fifth season is the first of several in which attention will be focused upon the range of rooms that ran along the northern side of the complex, from the Castellum Aquae in the east, westwards. The fieldwork this year investigated a zone (Area K) that lies on the western side of the early twentieth-century path that cuts through the complex from north to south, as part of a joint strategy of excavation and restoration, the latter being coordinated by the Soprintendenza Speciale per i Beni Archeologici di Roma (Ostia Antica). It is a particularly challenging part of the site, since it involves excavation of a partially standing structure, with archaeological remains on two storeys. Results so far have allowed us to identify at least five periods of occupation that find ready association with other parts of the Palazzo Imperiale excavated in previous years.
This rectangular opus testaceum structure, initially uncovered in 2009, was situated on either side of the twentieth-century path that runs from north to south in the direction of the Trajanic basin. The 2012 excavations revealed the full eastward extent of its walls, which intersected with a north–south opus mixtum wall that represented the western limit of the building. They also confirmed that its interior was structured around a central peristyle and surrounding vaulted passageway, and that it had an opus spicatum floor that revealed many phases of patching and reuse. In one of these (period 4) a glass-making workshop was identified.
This label is given to a complex range of rooms on three storeys that continued the northern sector of the Palazzo Imperiale westwards. The rooms were arranged around what was essentially a central peristyle (first floor), but which consisted of a combined rectangular cistern and light-well (ground floor). Today, only the ground and parts of the first floor survive. It is noticeable, however, that while the southern edge of this range of rooms continued in a straight line westwards, the outer face of the northern range of rooms that overlooked the Claudian basin ran at a northwesterly angle. Available evidence suggests that these rooms were constructed initially during the reign of Trajan, with several subsequent periods of use and structural change.
In constructional terms, the first structure established in this part of the site was what appears to have been a substantial opus caementicium mole that ran in a northwesterly direction, defining the northern edge of Room 8.5 (see below). It is likely that this represents the westward continuation of the Trajanic mole identified in Area B (Keay, Earl and Felici, 2011), although this has to be confirmed. Moreover, visual inspection makes it clear that it defined the whole of the northern edge of the Palazzo Imperiale, thus determining its characteristic divergent northwestern alignment. It may have acted also as a solid framework against which to absorb the outward spreading of the walls of the rooms on the northern side of the peristyle (Room 8.9).
The northern wall of the Palazzo Imperiale was built on to the upper surface of the Trajanic mole and ran in a northeasterly direction from a short brick-faced concrete wall that intersected with the east–west wall of Building 3. A vaulted north–south corridor (Room 8.2/3) occupied the space defined by Building 3 to the east, the northern edge of the Palazzo Imperiale to the north, and a range of rooms (Rooms 8.1 and 8.5, for example) to the west. It was entered by a doorway that provided access eastwards into Building 3 and by an opening in the wall to the north; it also had a cocciopesto floor, the gradient of which rose quite steeply as it headed southwards. In the later second century AD, the corridor was subdivided into a northern and southern space (Rooms 8.2 and 8.3 respectively) by a wall that was perpendicular to the eastern wall. A staircase was added in Room 8.3, providing access to the first floor space above. The western side of the corridor was defined by the rear opus mixtum wall of two vaulted rectangular rooms (8.1 and 8.4) that was covered with plain white plaster. However, a narrow access opened off the northwestern corner of the corridor into a vaulted space. This ran along the inside of the northern wall of the Palazzo Imperiale, and led into a vaulted corridor (Room 8.5) that defined all four sides of the rectangular cistern and light-well that supported the first-floor peristyle. Rooms 8.1 and 8.4 opened onto the eastern arm of this corridor. The first of these had a cross vault and cocciopesto floor, and was approached by a small entrance on its western side. Surviving travertine offsets and an associated drain arranged against its northern wall clearly indicate that this was used as a latrine. Light into the room was provided by a window on each side of the door to the west, two windows below (but off-centre to) each vault in the wall immediately above the latrine, and another two in the east wall. The second room (Room 8.4), similarly approached by an entrance on its western side, had a clerestory window on its east wall.
The organization of these rooms mirrors that of those on the ground floor. Little remains of the room that would have been situated above the north–south corridor (Room 8.2/3), or above Room 8.4. However, although the vaulting for Room 8.1 has been robbed away, the first-floor north and south opus mixtum walls of overlying Room 8.8, and associated flooring offsets, do survive, and it seems to have been used as a latrine. Elements of the flooring of Room 8.7, which overlies Room 8.5, survive on its southern side, although these are currently difficult to interpret, owing to later additions and the truncation of its northern wall. However, the provision of drains against its southern and western sides suggests that this too was used as a latrine.
There are no surviving structural remains of this. However, material on the floor of the first-floor rooms discovered in excavations in early 2013 (large chunks of brick and concrete, together with cocciopesto flooring and associated vaulting fragments) hint at the existence of a second floor. This accords well with a surviving piece of second-floor flooring in situ in Building 3 to the east (Keay, Earl and Felici, 2011).
Late antique activity
During the late antique period, Building 8 underwent important structural changes that, when considered in the context of what is known elsewhere, make a significant contribution to our understanding of the Palazzo Imperiale as a whole. In the later fifth century AD, for example, a drain was cut from north to south along the western side of Room 8.3 and provided with a decorated drain cover. In the earlier sixth century, the opening in the northern wall of Room 8.2, which looked out over the Claudian basin, was blocked up, restricting natural light. In addition, the Trajanic drain was robbed out, presumably in an attempt to gain access to its lead pipe, and the space then backfilled with rubble. Last but not least, the later second-century AD steps were demolished and replaced with new ones, indicating that the first floor was still in use at this late stage in the life of the complex.
In an attempt to understand better the internal organization of the building tentatively identified as navalia (Building 5) (Keay et al., 2012), the whole complex was resurveyed with ground-penetrating radar in June 2012, but this time using finer, 0.25 m, spacing traverses. Analysis of the data is now largely complete and generally confirms earlier published interpretations of the layout of the building. In September, a ground-penetrating radar survey was conducted on the site of the Horrea-Terme structure (Keay et al., 2005: 102–5, figs 5.26, 5.27), with a view to understanding better its layout and relationship to adjacent Building 5. Analysis of the results has revealed additional structures that will help determine the function of the complex.
- Keay, S., Millett, M., Paroli, L. and Strutt, K. (2005) Portus. An Archaeological Survey of the Port of Imperial Rome (Archaeological Monographs of the British School at Rome 15). London, British School at Rome.
- Keay, S., Earl, G. and Felici, F. (2011) Excavations and survey at the Palazzo Imperiale 2007–9. In S. Keay and L. Paroli (eds), Portus and its Hinterland (Archaeological Monographs of the British School at Rome 18): 68–91. London, British School at Rome.
- Keay, S., Earl, G., Felici, F., Copeland, P., Cascino, R., Kay, S. and Triantafillou, C. (2012) Interim report on an enigmatic new Trajanic building at Portus. Journal of Roman Archaeology 25: 484–512.