• 1 Mosaics with texts : Becatti 1961, p. 64-85 ; CIL XIV suppl. 4549.
• 2 Finley 1985, p. 195-196

1The piazzale delle corporazioni requires little introduction. It is without doubt one of the best known and most visited monuments in Ostia; its mosaics are reproduced often on postcards and posters, and its shape is familiar from numerous publications. But although the piazzale is well known, it remains a somewhat enigmatic edifice, a situation that is paradoxical seeing how at a superficial glance its purpose seems obvious enough. Both in text and image its mosaics clearly point to use by shipmasters from overseas1. Seldom, in fact, does an ancient structure provide us with so much detailed information through its visual and epigraphic material alone. Overall, the evidence that the building somehow facilitated overseas trade and shipping is strong enough to have made even Moses Finley uncomfortable, although he dismissed the piazzale as « a building with an uncertain function, that was at most a commercial office building with cell-like rooms »2. But despite the richness of the evidence, it is not easy to give an answer to the question of what role the building played in facilitating trade and transport.

• 3 Terpstra 2013, p. 95-124. See also Terpstra forthcoming-a ; Terpstra forthcoming-b.

2I have analyzed the piazzale before as part of a more comprehensive model of Roman long-distance exchange3. In this chapter, I will briefly recap my arguments and offer some additional thoughts to put the piazzale in proper perspective. This discussion will encompass both the initial function of the building and its subsequent reuse and metamorphosis into the structure we see today. I will argue that, placed in its architectural context, the piazzale is not as extraordinary or unique as it might seem to us now. In its original form it closely resembled the roughly contemporary porticoes to the theaters of Pompey and Balbus in Rome; in its changed shape it fits the evidence from the quadriporticus in Pompeii, a space also used as a theater portico and subsequently employed for different purposes. Finally, I will argue that close scrutiny of Filippo Coarelli’s comparison between the piazzale and the crypta Balbi disqualifies the idea that the temple in the center of the piazzale served the cult of Vulcan. I will conclude that the imperial cult fits better both with the material and epigraphic evidence and with my interpretation of the building as a place where foreign traders and shipmasters arriving in Ostia connected with their respective ethnic networks.

• 4 Battistelli – Greco 2002, p. 395-405 ; Meiggs 1973, p. 283 ; Pohl 1978, p. 215-216 ; Calza 1915, p. (...)
• 5 Vitruvius 5.9.1. This strictly utilitarian description passes over the range of possibilities of th (...)
• 6 See Sear 2006, p. 27-29 ; Sear 1990 ; Small 1983. Sear remarks that the Ostian theater is a rare ex (...)
• 7 Coarelli 1997, p. 451. Augustus probably built a bigger theater than envisioned by Caesar (with who (...)
• 8 The theater of Pompey was dedicated in 55 BC, the theater of Balbus in 13 BC. An inscription (CIL X (...)

4In large part this is the result of its change in use: it was not always a place serving overseas trade and transport, nor was it originally constructed to be one. It is directly connected to Ostia’s theater, built in early Augustan times, and originally served as a theater portico4. A passage from Vitruvius explains why a theater should have such a portico behind the scaenae: during rain intermissions, spectators could take shelter under its roof and the building could also accommodate chorus rehearsals5. Apart from a number of Greek examples, the building Vitruvius identifies as a template for this design is the theater of Pompey. But although the Vitruvian theater plan was not universally adopted – a topic over which much ink has been spilled6 – the idea of constructing an adjoining portico seems to have appealed in Augustan Rome. The theater of Marcellus, for instance, was placed too close to the Tiber to allow of a portico worthy of the name; still, erecting one was attempted, no matter how cramped the result7. Disregarding the theater of Marcellus with its truncated, almost non-existent portico, the two buildings that are closest to the Ostian theater complex architecturally, chronologically, and geographically are the theater of Balbus with the crypta Balbi and the already mentioned theater of Pompey with the porticus Pompeiana (fig. 2)8.

• 9 Aulus Gellius NA 10.1.7 ; Tertullian On Spectacles 10.5. See Sear 2006, p. 57-61 ; Holleran 2003, p (...)
• 10 The tholos temple (Temple « B ») seems roughly to have been the focal point for the complex’s axial (...)
• 11 Vitruvius 5.3.2 prescribes that theater auditoria should face away from the sun, but the evidence f (...)
• 12 Holleran 2003, p. 54 ; Coleman 2000, p. 222 ; Coarelli, p. 543-544. See also Hanson 1959, p. 43-55.

5Pompey’s theater was the first permanent one to be built in Rome, even if Pompey tried to maintain the fiction that it was in actuality a monumental staircase leading up to the temple of Venus Victrix9. A large portico connected the theater with the Republican victory temples in what is now Largo Argentina, enveloping and incorporating them into its enclosure. It would seem, in fact, that the orientation of these old sanctuaries dictated the orientation of the opera Pompeiana10. Theaters built both previously and subsequently, the ones at Ostia and Pompeii for instance but also the theater of Marcellus, show that caveae could have an entirely different orientation11, and it would seem that Pompey’s desire to incorporate the manubial temples into his edifice was the leading consideration behind its west-east axis. The old Republican sanctuaries faced east with Pompey’s portico and theater behind them, and were thus turned into a monumental facade to the whole complex, a step clearly intended to evoke a venerable tradition of constructing triumphal monuments12.

• 13 Sear 2006, p. 65-67 ; Manacorda LTUR, s.v. Crypta Balbi ; Gatti 1979.
• 14 Coarelli 1997, p. 222-223 ; Manacorda LTUR, s.v. Theatrum Balbi, and Crypta Balbi ; Manacorda 1990. (...)

6The slightly younger theater of Balbus follows the same orientation as that of Pompey, perhaps in direct imitation. From this theater as well a U-shaped colonnade, the crypta Balbi, projected east, a building closed to the outside with its three inner sides open to a central courtyard13. A badly mutilated fragment of the Severan Marble Plan shows it had a centrally placed building, the purpose of which remains debated. A temple of Vulcan is known to have stood in the Campus Martius, and Filippo Coarelli proposed interpreting the structure in the crypta Balbi as this sanctuary. However, Daniele Manacorda has suggested placing the temple of Vulcan outside the theater, west of the cavea, proposing the structure in the crypta Balbi was a different temple, or perhaps a fountain or honorary monument14. The matter need not be explored further here, but I will return to Coarelli’s suggestion at the end of this chapter.

• 15 Battistelli – Greco 2002, p. 396, fig. 3 and 4.

7Though the Roman structures and the piazzale vary in size, in all three cases we see the same layout of a cavea with an attached U-shaped colonnade. In all three cases we may also see the incorporation of sanctuaries, although this remains uncertain in the case of the crypta Balbi. But comparing the porticus Pompeiana to the piazzale, what seems remarkable is that the temple on the latter has an orientation that is turned 180 degrees relative to the manubial sanctuaries recruited as a facade for the former. The Largo Argentina temples have their back turned towards the theater of Pompey while the piazzale temple faces the Ostian theater. At first glance the orientation of the piazzale temple seems odd. The piazzale has a monumental entrance on its short northern end, consisting of twelve piers of tufa blocks; the temple in its center clearly disregards this entrance, turning its back towards it. At the same time, the temple’s orientation makes little sense viewed from the theater; from the seating area, it will have been obscured by the scaenae wall. The explanation for this orientation is that the monumental entrance was blocked off at some point in time, meaning access to the piazzale was restricted to narrow passageways in its southeast and southwest corners15. Only a visitor entering the building through these passageways would be greeted by the temple facade, just like the modern tourist is today.

• 16 Temple Domitianic in date, see Van der Meer 2009, p. 169 ; Meiggs 1973, p. 286. Battistelli – Greco (...)

8A difficulty here is that brick stamps from the temple suggest construction in Domitianic times while the blocking of the monumental northern entrance has tentatively been dated to the time of Hadrian. The construction sequence on this end of the piazzale is still not fully clear though16. In addition, here as everywhere we need to keep in mind that not all evidence survives archaeologically. The northern entrance may initially have been closed off by permanently locking a metal gate or wooden doors, to be blocked up with masonry only later. Supporting this idea is the fact that the division walls between the rooms in the colonnade seem to have changed from wood to stone.

• 17 But see Steuernagel 2004, p. 198-200 and Pohl 1978, who maintain that the piazzale always remained (...)
• 18 CIL XIV suppl. 4549, nrs. 17, 19, 43, 1.
• 19 See Meiggs 1973, p. 283-286 ; Terpstra 2013, p. 104-105.
• 20 The stone walls visible now are built on top of the mosaics, showing that they are a late addition. (...)

9With the blocking of the large northern entrance, the building ceased to be a public monument connected to the Ostian theater17. Because it had become an enclosed space with limited access, it will have acquired a rather intimate atmosphere, even if the destruction of the surrounding walls makes this difficult to appreciate today. Apart form the blocking of the large entrance, another important architectural change was made to the building: the colonnade was divided up into 61 small rooms, each about 4.20 meters wide and 4.50 meters deep. Floor mosaics in front of the rooms refer mostly to groups of foreign shipmasters such as the naviculari Gummitani (Africa) and the naviculari Turritani (Sardinia) although Ostian groups like the bargemen (the codicari) and the caulkers and the rope makers (the stuppatores and the restiones) are also represented18. The mosaics visible now, though probably laid incrementally over time and not attributable to a single event, seem to be fairly late in date. However, we know that at least one older series existed. Little survives of these older mosaics, but a certain continuity seems to be confirmed by the fact that the stuppatores and the restiones were represented also in the older series19. Whatever the exact date of the mosaics visible now, the modestly sized booths they identify were probably originally separated by wooden partitions, to be replaced by stone walls only during the building’s final phase20.

• 21 See Van der Meer 2009, p. 172-173 ; Terpstra 2013, p. 105.
• 22 Lanciani N.d.sc. 1881, p. 114. See also Riemer 2004, p. 246-247.
• 23 IGRR I, 421. See Terpstra 2013, p. 70-84.

10With these architectural changes, the building was probably frequented only by people who had specific business in the stalls around the portico. However, the shift from public to private use does not imply that the building became privately owned. Sixteen marble bases of honorary statues datable to the mid- to late second century AD were found on the piazzale, and nine of those show the abbreviated phrase L(ocus) D(atus) D(ecreto) D(ecurionum) P(ublice), demonstrating that the piazzale continued to be a public space controlled by the Ostian city-council21. Stamps on a lead pipe found in the central open area with the words coloniae colonor(um) ost(iensium) confirm the public nature of the building22. But all the same, it was groups of private individuals, mostly from cities overseas, who occupied the stalls around the central square and who probably came to dominate its day-to-day aspect. Perhaps these groups paid the Ostian treasury a certain sum in rent for the privilege of occupying a stall on the piazzale. A famous inscription from another important commercial harbor, Puteoli, shows how a group of Tyrians paid a monthly rent for the trading station they maintained there23.

• 24 The theory these ideas are based on comes from the fields of economics and anthropology, and the pr (...)

12However, as immigrants they remained an ethnically distinctive foreign entity. Because they consciously cultivated their distinctiveness and never blended in completely with their new environment, they could act as a liaison for itinerant merchants and shippers from their hometown. Such itinerant merchants and shippers could acquire trust and gain access to the business community in the city they sailed to by associating themselves with the group from their native city that had settled there24.

• 25 CIL XIV suppl. 4549, nrs. 40, 32, 18, 14.
• 26 See Kessler – Temin 2007, p. 329.

13Applied to Ostia, this theory interprets the piazzale as the locus where the process of information-sharing and establishing inter-community trust took place. We see in the mosaics that the rooms there were assigned to groups from particular places like Alexandria, Narbo, Carthage, and Sabratha25. The concentration of various groups in a single location facilitated the circulation of information, both within and between groups26. An itinerant foreign trader arriving in Ostia could go to the specific booth on the piazzale maintained by his compatriots living in the city. He could prove his ethnic identity there, establish trust with the Ostian business community, and trade with Ostian merchants. However, if he failed to perform his contractual obligations, this would reflect badly on the group of settlers from his hometown. If the individual trader did not rectify any transgressions and modify his behavior, these settlers could respond by denying him access to their network. Expulsion would result in the individual trader being out of business in Ostia. Because the networks were based upon ethnicity, he could not join the people from a different town. No Ostian trader would have trusted him if he did not form part of the network of people from his native city, and he would therefore no longer be able to trade. The networks thus had a good deal of coercive power over their individual members, including the itinerant ones, a power dynamic that compensated for the lack of government enforcement of private contracts.

• 27 But see Manacorda LTUR, s.v. Crypta Balbi, p. 328 ; it is possible that reconstruction activity dat (...)

14By being divorced from the theater and partitioned up into small rooms the piazzale became an entirely different space from the entertainment structure it was initially built to be. Although the porticoes connected to the theaters of Pompey and Balbus seem never to have been altered in such a way27, there is another well-known structure in the Roman world where a comparable architectural process seems to have occurred, namely the quadriporticus (the « gladiators’ barracks ») in Pompeii. Unlike the crypta Balbi and the porticus Pompeiana we can still study and appreciate this building in its full dimensions.

• 28 Richardson 1988, p. 85 suggests an ante-quem date of the early first century BC based on the typolo (...)
• 29 On the date of the theater, see Mau 1906 ; Richardson 1988, p. 76-77 ; Parslow 2007, p. 212-213. Se (...)

15A firm date is not available for the Pompeian quadriporticus, but without question it predates the porticoes discussed so far by a considerable margin28. Unlike the Roman and Ostian structures it was probably not built contemporaneously with the theater it is adjacent to - Pompeii’s « large theater » - the first phase of which may be older by as much as a century29. But either way, looking at the quadriporticus and the large theater in plan, it is clear that the former was built in extension to the latter (fig. 3).

• 30 Poehler – Ellis 2012 ; Poehler – Ellis 2013, p. 12-13.
• 31 Although Richardson 1988, p. 83 tentatively prefers to see it as post- rather predating the quadrip (...)
• 32 Richardson 1988, p. 83 ; Coarelli 1997, p. 576-577. Richardson proposes that the Doric colonnade wa (...)

16It is worth noting in this respect that the area the quadriporticus came to occupy had always been a large open space, as revealed recently by ground penetrating radar30. The building seems to have architecturally codified a pre-existing situation, although a portico with columns in the Doric order, the northeast corner of which can still be seen, may have preceded it31. The relationship of the open area to the theater in the earlier period is unclear, but that the quadriporticus at some point in its history served as a theater colonnade is not in doubt32.

• 33 Garrucci 1853 first proposed this interpretation and coined the term ludus gladiatorius. He notes ( (...)
• 34 Richardson 1988, p. 85-86 ; Jacobelli 2003, p. 39-52.

17But at the time Mt Vesuvius erupted it had undergone repeated and substantial restructuring and was connected more with its surrounding urban fabric than with the theater. It has three access points from three different orientations: an exedra to the south, a staircase leading down from the Triangular Forum to the west and, hidden behind a screen wall of three Ionic columns, an opening to the east that led to the via Stabiana through an alleyway. The artifacts discovered during the excavations in the 1700s also point in a different direction than use as a Vitruvian portico avant la lettre. Gladiatorial equipment was found in some of the rooms of the southern colonnade, and the exedra displayed several graffiti mentioning gladiators. This evidence has given the building an undying place in the popular imagination as the barracks where Pompeii’s gladiators trained and slept, although this reading is open to doubt33. Lawrence Richardson, though tentatively accepting the interpretation, has pointed out that if the structure was indeed used as a training ground, one would expect to find baths attached to it somewhere. In addition, not all finds accord with the interpretation of barracks, like a storeroom apparently filled with household goods. It should also be noted that graffiti mentioning gladiators and gladiatorial games can be found in large numbers elsewhere in Pompeii, so their presence here might not be as significant as it seems34. Nonetheless, the combined evidence of finds and graffiti seems too strong to be dismissed out of hand, and some connection to gladiatorial combat should probably be assumed. There are alternative explanations to barracks, though, for example shops selling or repairing gear.

• 35 The quadriporticus is ca 64 m. long, 52 m. wide ; the piazzale is ca 102 m. long, 80 m. wide.
• 36 Dyer 1871, p. 146 counts 66 rooms on the quadriporticus, but the upper-story rooms are included in (...)
• 37 Poehler – Ellis 2012, p. 8 fig. 13 ; Poehler – Ellis 2013, p. 6 fig. 7. See also Richardson 1988, p (...)
• 38 Poehler – Ellis 2011, p. 8 ; Poehler – Ellis 2012, p. 9-10 ; Poehler – Ellis 2013, p. 12-13.
• 39 Note how the piazzale as well had large public sewers running underneath it ; Battistelli – Greco 2 (...)

18The quadriporticus and the piazzale show some interesting parallels. Although the quadriporticus is appreciably smaller than the piazzale35, the number of ground-level rooms it contains is comparably high: circa 43 for the quadriporticus against 61 for the piazzale36. Research on the architectural history of the quadriporticus has only recently been undertaken, but preliminary results show that there were no rooms in the colonnade in the building’s first phase37. We do not know whether the rooms that were eventually constructed were used for public or private purposes, but the building as such in all probability always was a space controlled by the city. Pompeii’s largest sewer (the « Altstadt » sewer) ran underneath the western portico, managing the waste from four public latrines and the surface drainage from the city-streets. In the quadriporticus, work was done on a section of this drain up until the last years before the eruption38. The fact that the building incorporated the infrastructure of public urban amenities suggests that it was, and always remained, publicly controlled, just like the piazzale39.

• 40 The « Pompeii Quadriporticus Project » ; see the references to the work by Poehler and Ellis in the (...)

19I am certainly not proposing that the two buildings were similarly used based on the parallels just outlined. The material evidence prevents that conclusion, and the different nature of Pompeii and Ostia also suggests otherwise; Pompeii must have had a river or marine port somewhere, but it was not a major commercial harbor like Ostia, visited by large numbers of foreign shippers. But what matters for my argument is that a portico that at one point served public entertainment was in the course of its history turned into an inward-looking space sectioned up into a large number of cell-like rooms. No floor mosaics like the ones on the piazzale were found in front of those rooms, and ultimately we may have to accept that determining their use is impossible. However, the quadriporticus, a sadly neglected Pompeian monument, is now the subject of an ongoing architectural study by Eric Poehler and Steven Ellis40. It will be interesting to see what conclusions this study ultimately reaches.

• 41 Coleman 2000, p. 219.

20As remarked above, there is no clear evidence to suggest that the crypta Balbi and the porticus Pompeiana were ever divided up into smaller compartments used for purposes unconnected to their respective theaters. As to the question of why this happened in Ostia and Pompeii and apparently not in Rome, we can only speculate. One reason might be that the Roman buildings formed part of victory monuments built by generals from Rome’s revered Republican past. One can see how turning such monuments into something other than what they were intended to be might not have been contemplated lightly. In addition, and in accordance with that line of thinking, theaters were a luxury and represented « conspicuous consumption » of urban space41. Fully functional only every so often, their large enclosures stood empty and unemployed for much of the time. Although their porticoes might have served as public gardens – the porticus Pompeiana certainly did – they too were used for their primary purpose as entertainment structures equally sporadically. Perhaps this element of « conspicuous consumption » was more highly prized – or more readily tolerated – by the imperial capital than by the more peripheral cities of Ostia and Pompeii.

• 42 Suetonius Nero 37.1. See Terpstra 2013, p. 78, 146.

21But in any case, the quadriporticus shows that transforming a theater portico architecturally and giving it a new purpose was not unique to Ostia, even if in the case of the Pompeian building we do not know exactly what that new purpose was. A Suetonius passage shows that conversion of pre-existing structures into meeting places for foreigners was also not unique to Ostia. The senator Salvidienus Orfitus rented out several rooms of his Roman house to foreign groups, although he ran afoul of the emperor Nero and ultimately paid dearly for this decision42. Such tantalizing parallels in the material and literary evidence should lead us to question if the piazzale was as exceptional in antiquity as it seems to us now.

• 43 But see Gialanella – Sampaolo 1980-1981, p. 150-152 who tentatively interpret a colonnaded structur (...)

22The inscription from Puteoli already alluded to earlier, providing evidence for a trading station of Tyrians, warrants mentioning again in this regard. From this inscription we know for a fact that a group of Tyrian merchants maintained a trading station in Puteoli, although no trace of this station has ever been found43. The inscription boasts about the building’s lavish embellishments, and it seems likely that at least some of these will have contained ethnic references to Tyre. If anything had survived we might have had a context for the piazzale. Unfortunately, loss of evidence has deprived us of that possibility, a point worth considering in more detail. Apart from being exceptionally well preserved, Ostia harbors a large amount of a particularly durable form of in situ evidence in the shape of floor mosaics. Alternative ways of signposting buildings had a far greater chance of disappearing. Sculpture was frequently reused as construction material or burned for lime in the post-classical period, while bronze ornaments were often melted down. Even if bronze entered the archaeological record, it slowly corroded away in the course of the centuries. Wall paintings do not preserve as well as mosaics, while decoration made from organic material like wood or cloth generally does not preserve at all. In short, the uniqueness of the piazzale in our available body of evidence may in large part be the result of Ostia’s fondness for floor decoration and its remarkable state of preservation, in combination with loss of evidence elsewhere.

• 44 Lanciani N.d.sc. 1881, p. 114 seems to have been the first to propose the cult of Ceres ; for the « (...)
• 45 Rieger 2004, p. 90-92, 243-249.
• 46 See Pensabene 2005, p. 502-503 ; Steuernagel 2004, p. 200.

24The suggestion of Ceres is pure conjecture based principally on the large number of references to the grain trade – ears of grain and grain measures – in the mosaics. But this explanation only fits part of the evidence, seeing how shippers transporting other commodities also demonstrably frequented the piazzale. The mosaic of one stall mentions the « wood shippers » (« naviculariorum lignariorum ») while others show depictions of amphorae, all indicating trade in something other than grain44. As for the suggestion of Pater Tiberinus, this rests on extremely thin and questionable evidence. A passage from Ovid’s Fasti mentioning Ostian atria Tiberina forms a major part of the argument45. However, the piazzale temple had not been constructed yet at the time Ovid wrote, and there is no evidence whatsoever that it was preceded by an earlier, Augustan sanctuary. It also seems rather unlikely that a temple to Pater Tiberinus would have been built with its rear end turned towards the Tiber46.

• 47 Coarelli 1997, p. 222-226. For the inscriptions, see Pellegrino 1986, nrs. 3 and 5.
• 48 It does not matter in that respect whether the central building was constructed with the rest of th (...)

25The suggestion of Vulcan, put forward by Filippo Coarelli, is more sophisticated and merits a lengthier discussion. It is based on two inscriptions containing references to Vulcan found near the theater, and on a comparison with the crypta Balbi as a space similar in layout to the piazzale: a three-sided portico with a building in the central open area47. Coarelli argues that the crypta Balbi was the seat of the praefectura vigilum, whose members he sees venerating their patron god in the central building. This situation would then compare to the one in Ostia, where the barracks of the vigiles were located close to the piazzale. Hard evidence for placing the Campus Martius Vulcan temple in the crypta Balbi is lacking, and Coarelli’s suggestion is certainly not universally accepted. But more importantly, the comparison overlooks the fact that the central structure in the crypta Balbi probably formed part of the original plan48, while the temple in the piazzale is a later addition. Key here is its orientation facing away from the blocked-up entrance. This position suggests that it was constructed only when the portico around it had ceased to be a theater colonnade and had become an enclosed space visited by a restricted group of people. By implication, it almost certainly served only that restricted group: the people represented in the mosaics. The Ostian vigiles are not mentioned in any of those, and there is nothing to suggest that they had any business in the building; the proximity of their barracks does not change that fact.

• 49 Pensabene 1996, p. 213 ; Pensabene 2002, p. 205-207 ; Pensabene 2005, p. 502-504. An Ostian templum (...)

26The worshippers visiting the central temple should thus be sought inside, not outside the piazzale. But with so many groups of such varying nature present in this location – traders and shipmasters from Egypt, Sardinia, Gaul, and Africa, Ostian bargemen, craftsmen, and artisans – it seems hard to think of a god or goddess that would have appealed to them all. These groups simply seem too diverse for any single kind of religious expression. Only one exception comes to mind: the imperial cult. Patrizio Pensabene first suggested this idea, basing his argument on four inscribed statue bases from the piazzale mentioning flamines of the deified Vespasian, Titus, and Hadrian and on the structures flanking the temple, a feature said to be typical of templa Divorum in Hispania49.

• 50 Van der Meer 2009.
• 51 Note, though, how the last two arguments assume some connection between the piazzale temple and the (...)

27Bouke van der Meer elaborated on this idea in a recent article, adding several arguments to Pensabene’s: Suetonius mentions a collegium Flavialium, apparently a « guild » of priests instituted by Domitian; given the building activity of the emperor in Ostia and the Domitianic date of the piazzale temple, it could be that it was constructed as part of a larger push to promote the Flavian dynasty50. The elliptical text of a fragmentary inscription found in the temple cella could refer to the imperial cult, while fragments of over-life-sized marble statues found on and near the piazzale could have been representations of emperors. Two inscriptions commemorating the enlargement of a sanctuary by an ordo corporatorum might refer to the annexes flanking the piazzale temple; since no patron divinity of this ordo is known, it could be that its members venerated gods of common interest like deified emperors. An epitaph of a flamen of the deified Hadrian mentions how he had sponsored theatrical performances during his tenure; seeing how he undertook this initiative in his capacity as flamen, he could have been a priest connected to the piazzale temple. Finally, Van der Meer points to a theater in Leptis Magna with a trapezoidal portico behind the scaenae; in its center stands a temple that was for certain dedicated to emperors, providing a possible parallel to the Ostian structure51.

• 52 For the position of the emperor in imperial ideology and Roman religious life, see Ando 2000 p. 385 (...)

29The piazzale allowed foreign traders and shipmasters to identify themselves and show their group membership, facilitating the establishment of trust between the different trading groups. In this interpretation, a temple devoted to the imperial cult could help groups of diverse ethnic and religious background to communicate by providing them with a common point of reference and a shared way of religious and ideological expression52. The piazzale served as the physical point of connection between foreign individuals and their ethnic networks, and by extension between foreign individuals and the native Ostian business community. By having a temple of the imperial cult in the midst of the piazzale, foreign traders and shipmasters could simultaneously associate themselves with their cities of origin - through their labeled stalls - and with their Roman host city through participation in the imperial cult. If this view is correct, then the temple enhanced the functionality of the piazzale as a building that facilitated long-distance, inter-community trade.