In 2001 the Department of Classics at the University of Texas at Austin received a five-year permit from the _Soprintendenza_ of Ostia Antica to study the ancient synagogue and its urban environment. Discovered in 1961, the synagogue was originally excavated by M. F. Squarciapino. Subsequent campaigns were undertaken in 1977-79 and 1983-85. These brought to light an area of baths and shops located on the other side of the ancient coastal highway, the _via Severiana_. To date, little has been published about these excavations. Architectural drawings were never completed for areas uncovered in the 1980s. No final authoritative report of the synagogue excavation exists. In 2001 the University of Texas created the Ostia Synagogue Masonry Analysis Project (OSMAP) with two goals. The first aims to supplement the material gathered during previous excavations with new data. Consequently, the OSMAP team devised a methodology for measuring, drawing, elevating, digitally mapping, and analyzing the masonry techniques used in the construction and repair of the synagogue. In subsequent seasons, OSMAP hopes to use these techniques to refine our understanding of the building’s phases. This topic is hotly debated among archaeologists, social historians, and scholars of ancient Mediterranean religion. The second goal aims to provide a definitive plan, architectural history, and digital reconstruction of the synagogue and its neighboring buildings. To begin, OSMAP established an official numbering system for this zone of Ostia Antica. Adopting the standard formula used throughout the site, this system designates: (1) the region of the city (“I-IV”) (2) the _insula_, or block; (3) the number of the building within that block; and (4) the rooms within the building. The OSMAP survey region along the _via Severiana_ to the east of the Porta Marina baths (IV.10.1-2) has, accordingly, now been designated Region IV, _insulae_ 14-17. The synagogue itself is designated as IV.17.1, with room numbers 1-18. The _edificio con ninfeo_ is designated as IV.17.2, with room numbers 1-10. The _edificio accanto alla via della Scafa_ is designated IV.17.3, with room numbers 1-4. The Baths of _Musiciolus_ are designated IV.15.2, with room numbers 1-35. The shops which adjoin the baths and face the _via Severiana_ are designated IV.15.1.1-6. In 2001 this system was approved by the _Soprintendenza per i beni archeologica di Ostia_ (Dtt.ssa A. Gallina Zevi) and the head of the Ostian archives (Dtt.ssa E. J. Shepherd). The OSMAP team then executed a GIS survey and architectural drawings of the synagogue and its neighboring structures, including for the first time the entire edificio con ninfeo. With the approval of the _Soprintendenza_, survey points were permanently marked in modern concrete throughout the area with a pin and aluminum tag (‘OSMAP 2001 UT’). These points were linked in by GIS with three survey points already marked by the Deutsches Archäologisches Institut during their campaigns at Ostia (DAI survey points 1013, 1015 and 1136). An additional, digital top-plan of the site was then drawn. The data points will form a valuable reference for future study and excavation.

In 2002 an OSAMP team comprising 14 student workers and 5 senior staff members returned to the area to conduct a masonry analysis of IV.17.1-3. Working in teams of two or three, the OSAMP staff assembled a detailed catalogue, including architectural drawings, of all wall segments at the synagogue (IV.17.1) and its adjacent structures (IV.17.2-3). This analysis included measurements and descriptions of the following: all wall lengths, heights, and widths (differentiations were made between ancient and modern sections of the extant walls); a selection of tufa blocks, clay bricks, and mortar beds from each wall; all visible quoining, framing, or bonding techniques which characterized individual wall sections, where appropriate; and all features, such as thresholds, windows, benches, etc., which formed part of the ancient phases of the building. A‘5+5 modulus’ (five courses of tufa or brick plus five courses of mortar, measured in 1 m increments) was also recorded, where evidence permitted. Once completed, each team then provided an assessment of the relative chronology of construction techniques used in their assigned rooms. This study has yielded the following preliminary results: A total of 10 masonry types and subtypes were employed in the construction and repair of the buildings in the synagogue complex (IV.17.1-3). Modulus measurements of the purported earliest type, _opus mixtum_ A, are consistent throughout the site; these measurements vary no more than ± 0.05 m. This data suggests that the superstructure of rooms 7, 9-10, and 14 was likely constructed at the same time. They may have even constituted the walls of an early structure. Today, these walls form the “shell” of the visible structure of building 1. No partition walls, however, have survived from any earlier phases. This fact suggests that the interior spaces of building 1 witnessed significant modifications over time. Building 2, on the other hand, the _edificio con ninfeo_, was constructed in _opus mixtum_ B although this technique was also identified in portions of building 1 (for example, in room 18, the southern wall). An absolute chronology for the phases of these construction techniques and repairs cannot as yet be determined from the available evidence for two reasons. First, techniques like _opus mixtum_ A (which use _latericium_ bedding courses at regular intervals) are now known to have been used at Ostia into the mid and late second century with some examples extending into the third (see van Dalen, below). Second, no stratigraphic data exists from the site’s earlier excavation, either in print or in the Ostian archives. Further data, acquired through more scientific excavation, will now be needed to refine the individual phases of all three buildings in the survey area.

Having analyzed the masonry of IV.17.1.1-3 and IV.15.1-2 during the previous season, the team returned to record other evidence for the uses of _opus mixtum_ A, B, and C at Ostia. The purpose of this season was to document techniques used in dated, or datable, contexts so as to suggest chronological parameters for the construction phases of the buildings at IV.17.1-2. The database of these measurements and the buildings from which they were taken is forthcoming. Members of the staff were also granted permission to clean, draw, and photograph previously excavated but unpublished trenches (= ‘T’) from the 1960s excavations, now designed T Alpha (α), Beta (β), and Gamma (γ). Tα is located in IV.17.1.12 (the room defined by the central columns). Tβ is located in the southeastern corner of IV.17.1.9. Tγ is the interior of the Torah niche, located in IV.17.1.13. Due to the presence of poured foundations, none of the balks of Tα (IV.17.1.12) preserves a stratigraphic profile. Tβ (IV.17.1.9) revealed two earlier features of the building never reported. The first is the remains of a threshold and doorway, both of which predate the extant mosaic floor in room 10. Adjacent to this earlier threshold was also discovered the foundation of a supporting pier, or wall spur, which originally projected c. 0.15 m into the room (room 9). Although the current evidence for the separation of rooms 9 and 10 does replicate this same spatial division, the removal of the pier, or wall spur, in a later phase suggests a slight remodeling of the earlier space. The absence of any stratified ceramic or numismatic evidence has cautioned against assigning an absolute date to these phases. Tγ revealed the following features: The mosaic pavement located outside the Torah nice (in IV.17.1.14) continues under the aedicula into Tγ. Within Tγ evidence for this mosaic extends 0.62 m to the south; it measures 0.55 m at its widest extent. On the south it abuts a tufa platform, 0.785 m high. This platform measures 1.53 m from north to south; it is 0.60 m wide. On its east side it abuts a _mixtum_ A reticulate wall, measuring 1.30 m, north to south. To the east of this wall is cocciopesto surface, located at the level of the _latericium_ bedding course in the _mixtum_ A wall. This surface (1.944 m ASL) is roughly at the same level of the foundation for the mosaic floor (2.002 m ASL) although the two are not contiguous. Finally, a field-walking survey of the site was conducted to plan future areas of research. The team noticed the damaged remains of a reticulate wall, never recorded on any plan of the buildings at IV.17.1, located at the southeast corner of IV.17.1.10, directly to the north of the modern highway ( _via della Scafa_ ). This wall appears to abut the exterior wall of IV.17.1.10, suggesting that it was constructed at a later time. Excavation is planned to investigate the relationship between this wall and the extant remains of the building.

In 2004 the team began a study of all remains unearthed during the 1961-1963 excavations of IV.17.1-2. None of this material has been published or analyzed in any systematic way. Relevant entries in the Giornali di Scavo were consulted to shed light on the methods employed at the time of excavation. None of the 1961-1963 excavations used modern stratigraphic methods. As a result, it has been proven difficult to analyze the archaeological context of the material stored in the Ostian warehouse. Written records have provided only minimum supplementary data. Objects unearthed during excavation were stored in paper bags; handwritten labels document only general details of an object’s findspot (“ambiente col forno”). Other bags contain paper slips with similar notations. These labels have been most helpful when they record relative stratigraphic information (“object found under the mosaic” or “under the terra battuta floor on top of the mosaic”). The team began by separating all the material by type (ceramic, wall plaster, marble, glass, and so on) with the aim of identifying any datable remains (ceramic indicators or identifiable coins). The handwritten notes and notations in the Giornali were then consulted to determine any known, relative context. Preliminary results have raised questions about the sequence of phases traditionally assigned to the architectural remains of the synagogue. Analysis has brought to light evidence of a habitation phase not yet discussed in any secondary literature. The Giornali di Scavo (1961-1962, p. 18-19) records the discovery of a Roman coin of _Maxentius_ which was discovered underneath the mosaic foundation of the room with the oven (IV.17.1.10, “ambiente col forno”). This material provides a secure _terminus post quem_ for the extant mosaic floor. Prior to reaching the level of the mosaic, however, excavators had already identified and removed traces of a terra battuta, or beaten earth, floor at a higher elevation. This habitation layer was never studied as a distinct phase in the building’s history because ceramic material from it seemed to date between the second and fourth centuries C.E. These ceramics, preserved in the Ostian archives, now await a renewed study. At present, it is clear that coin beneath the mosaic and the presence of a floor level at a higher elevation demonstrate that there was not one but two Late Antique phases in this room. The first of these dates to the fourth century; the second calls for further investigation, perhaps in unexcavated areas of the site. The area surrounding the reticulate wall in IV.17.1.6 (see entry 2003) was explored as one possible area of undisturbed ancient stratigraphy. A small probe (T1) was also begun in IV.17.2.10. Its purpose was to investigate whether a small wall feature on the west side of IV.17.1.18 may have at one point in time extended into the corridor of IV.17.2.10. Preliminary investigation suggests that they do and that they are worth exploring again in the future.

OSMAP opened several strategic trenches (= ‘T’) in 2005 (T2-7). The goals were four-fold: (1) to reveal the extent of the ancient walls beneath the surface of the soil; (2) to document the masonry techniques used in the construction of these walls, where available; (3) to compare and contrast these techniques with the walls of the extent structure above; and (4) to expose the foundation levels of the walls. This work was undertaken in accordance with modern stratigraphic methods; and records were kept, including photographs, fields drawings, and elevations. Ceramic and numismatic finds were analyzed in 2006. T2 (IV.17.1.6) was located in the southeast corner of the site and was designed to explore the remains of a reticulate wall on the east external wall of room 10, never included in any earlier site plan. Excavation revealed that this wall was not bonded to the exterior wall of room 10 but that room 6 was a part of the building complex at one point in time. T6 revealed an area of ancient stratigraphy in three distinct phases. The most recent was a layer of collapsed roof tiles (approx. 2.055 m ASL). Underneath this collapse, the remains of a cocciopesto surface were discovered (approx. 1.875 m ASL), contiguous with the southern wall of room 6. Preliminary ceramic analysis suggests that the material between the collapse and the surface dates to fifth or sixth century C.E. The cocciopesto surface was left intact except for a probe executed in the southwest corner. It revealed the foundation stones of the south wall and the remains of a water basin at one time set against the east wall. T4 (IV.17.1.6), T5 (IV. 17.1.5), and T7 (IV.17.1.14), were excavated down to the foundations of the walls. T4-T5 were positioned in the eastern half of building 1 in rooms 5 and 6. T7 was positioned in the central hall of the synagogue (room 14). The results have provided new information about the construction of the present building. The poured concrete foundation of the wall in T4 extends to a depth of 0.023 m ASL whereas the concrete foundation of the wall in T7 extends to a depth of 0.46 m ASL. Distinctions in composition, inclusions, color, and profile suggest that the foundations of room 10 and room 14 may have been constructed at two different times. T6 was positioned to the west of building 1, directly north of building 2. It was designed to explore data gathered during a recent geophysical survey, conducted by the DAI-Rome in 2003-04, which had identified subsurface walls in this area. Excavation revealed that no subsurface walls exist. The only traces of a feature were located at the lowest levels of T6, where the remains of a compact surface were discovered (approx. 0.65 m ASL). This surface suggests some habitation or occupation here during the period antedating the construction of the _via Severiana_ and that ground level was raised significantly in this area (+ 1.793 m) prior to the construction of the road.

OSMAP opened several strategic trenches (= ‘T’) in 2007 (T8-14). The goals of T10-11 and T13-14 reprised objectives from 2005. Other trenches explored questions about later habitation phases in the synagogue (T12); and investigated features no longer visible above ground (T8-9, T15). Ceramic and numismatic finds were analyzed in 2008. T8 and T15 were positioned west of building 1, directly north of building 2, to continue exploration of the area along the _via Severiana_ (see T6 in 2005). T8 revealed a marciapiede, or sidewalk, in two layers of poured concrete, located alongside the basalt paving stones of the road. The higher layer (approx. 2.608 m ASL) extended approximately 2.70 m south from the basalt stones. The lower layer (approx. 2.378 m ASL) extended 0.86 m north from the south balk of the trench. T15, positioned to the south and east of T8, revealed further traces of the lower layer, suggesting that the marciapiede extended from the road, beyond the exterior façade of building 1, and towards the facade of building 2. T9 was positioned on the exterior north wall of building 1 west of room 1. Its goal was to study subsurface architecture partially revealed during earlier campaigns. Excavation revealed three features: (a) one north-south wall in poor condition, constructed of reticulate on both sides; (b) an east-west wall with reticulate on its southern face and three courses of _opus vittatum_ on its northern one; and (c) the foundation of a second north-south wall. Together, these walls formed a chamber (now designated room 2), approximately 1.50 m square, on the exterior façade of building 1. The relative or absolute chronology of these walls and their relationship with the exterior wall of the synagogue or nearby surfaces is under consideration. T10-11 were positioned along the north and south sides of building 1, room 11. T10 revealed the following relative chronology: The east wall of what later became room 11 is earlier than the north wall of room 11 (= the exterior, _mixtum_ A wall of the synagogue) because (a) the poured foundation of the east wall differs by inclusions, color, and composition from the foundation of the north wall; and (b) the foundation of the north wall has been poured around (but does not touch) the foundations of the east wall. T11 revealed that the synagogue’s columns (room 12) were re-erected on modern concrete foundations. Although ancient foundations for the columns are visible beneath this concrete, they appear later than the poured foundation for the east and west walls of room 11, on which they are set. This data suggests the following relative chronology: (a) construction of an east wall in what later became room 11, followed by (b) construction of the _mixtum_ A wall along the north, and finally (c) installation of the columns in room 12. Ceramic analysis may be helpful in assigning an absolute chronology although, as noted, both trenches did reveal evidence of prior excavation.

Three regions were studied: (1) the exterior north wall of building 1, outside rooms 7, 11, and 14; (2) the hall of the synagogue, IV.17.1.14; and (3) the area in and around room IV.17.1.18, including its adjacent corridor, IV.17.2.10. Two trenches were positioned on the exterior of the north wall: T18A and T18B. T18A revealed a set of brick steps ascending from the exterior into room 11. Several surfaces were also revealed beneath this feature. Stepped like a terrace as a result of previous excavations in the area, they ascended to north to the via Severiana. The OSMAP staff excavated all of these sealed loci and future excavations will hopefully clarify the relationships between the pavement levels, the building and the via Severiana. In T18B, positioned directly to the west of T18A, the same surfaces were found. One reddish-brown surface was identified as running beneath the exterior pier of the synagogue. It was a damaged cocciopesto surface. During its removal, a late fifth century AD coin was discovered beneath the pier. This find now provides a terminus post quem for the construction of the supporting pier. In room 14, two trenches were positioned to test the hypothesis that the building was constructed on top of a third-century ground-raising project. T16 was positioned in the northwest corner. T17 was positioned in the center of the room. Although the ancient floors were missing, and although there was modern backfill in both trenches, traces of sand, shell, and ceramic deposits were identified at roughly the same elevation. In T16, this material was located at 1.15 m ASL and contained ceramics datable between the first and third centuries (Olcese 1a, 3, and 4). In T17, this material was located at 1.12–18 m ASL and contained material from the mid second century (Tripolitana 1) and first through third centuries (Gauloise 4-5). Because the material from T16 was excavated next to the north wall foundations, it is likely that the standing architecture post-dates the mid second century, at the earliest. Finally, three trenches were positioned in IV.17.1.18 and IV.17.2.10 to explore features of earlier excavations that were photographed but never analyzed. T19 (on the east side of room 18) and T21 (on the west side of room 18) revealed the presence of a foundation wall, or perhaps a drain, with plaster facing beneath the floor of room 18. T20, located outside room 18 (IV.17.2.10) revealed a terra battuta surface (c. 1.60 m ASL). Ceramics from beneath this surface (c. 0.33–37 m ASL) suggest a date for it well in advance of the third or fourth century. This material seems to confirm the post-fourth-century phase of the building observed in 2004, in room IV.17.1.10.

In 2010, we continued with preparation for formal publication of materials from the 1960s excavations of the synagogue. We also completed the analysis of the ceramics and faunal remains from previous OSMAP excavation seasons. With these analyses complete, we revisited and dated the strata from trenches excavated in the 2005, 2007 and 2009 seasons. Daniela Williams produced a report on a group of coins discovered during excavations in 1962 and recorded by the Giornali di Scavo as having been found in “quadro 4B,” which corresponds to the northern half of Room 10 of IV.17.1. The assemblage, consisting of 51 base bronzes concreted together, was reportedly found between the mosaic floor and the cocciopesto surface below. Although the current location of the original specimens is unknown, each coin was recorded in a card catalogue, from which Williams was able to reconstruct and analyze the group as a purse or hoard. The group contained coins dating between 327 and 340/347 AD, suggesting AD 340 as a firm terminus post quem for the deposition of the coins and hence the construction of the mosaic floor of Room 10. Brent Nongbri produced a report bringing together the results of the analysis of the archival material completed in 2008. The report takes account of all known archival and published information on the 1961 and 1962 excavations and also includes a summary of the available evidence for excavations carried out in and around the synagogue in 1963, 1964, and 1977, for which no formal publications exist. The report details the methodology employed in Floriani Squarciapino’s campaigns and presents evidence for a number of finds that were informally recorded but never published. Synthesis of the data from the 2005, 2007, and 2009 OSMAP excavations yielded suggestive evidence about the uniform layer of sand beneath the entire area of the synagogue complex. The ceramic profile for the sand layer in all areas in which it was exposed shows a wide variety of sherds, but there is throughout a notable lack of African sigillata, which was ubiquitous at Ostia by the middle of the second century. This suggests a terminus ante quem for the sand layer.

The five trenches (= T) excavated in 2011 (T18b Extension, T22-T25) revealed a greater number of surfaces and more sealed loci than all other excavation seasons combined. T18b (2009) was located north of IV.17.1 facing the Via Severiana. In 2011, we reopened the western end of this trench and extended it to the north (T18bE) to explore the relationships among the synagogue building, the pavements from T18b, and the Via Severiana. T18bE in 2011 raised more questions than it answered. The individual layers of pavement, so clearly defined in the north balk of the 2009 trench, extended north a short distance before disappearing into a thicker matrix of pavement, the west side of which contained a circular pit cut with a round raised center (the whole resembling the impression of a car tire). It may have been a base for a mile marker for the Via Severiana or part of a later construction for a utilitarian use. T22 was placed at the NE corner of IV.17.2, adjacent to the entrance to the building to discern the relationship of the foundation of the western porch wall to the main building structure. We excavated several sealed surfaces and uncovered the remains of a reticulate wall built along the exterior of the western porch wall of Building 2. We also uncovered a pit dug along this reticulate wall, through all of the pavements, into which amphorae had been set. This could represent a late antique storage area. T23 was placed in IV.17.2, Room 10, in the southern area of the space between Building 1 and Building 2, in order to ascertain the relationship between these buildings. This area had been only partly excavated by Floriani Squarciapino. We uncovered the remains of a floor surface that had been partially disturbed by previous excavations (perhaps an impluvium), below which we found a drain that ran south before turning sharply west. This drain post-dates both the eastern wall of Building 2 and the southern wall of Room 10. Below the level of the eastern wall of Building 2 we uncovered an earlier foundation running at a different angle from the existing wall; it appears to be on the same line as the walls of the nymphaeum to the south. T24 is located within Rooms 15 and 16 of Building 1, in an area only partly excavated in the 1960s. We discovered 4 floor levels containing charred pottery and carbonized remains indicative of cooking. The lowest excavated level was a uniformly compacted dirt surface, which yielded a Vespasianic quadrans (67-77 CE), but ceramic evidence suggests a date of the second century CE or later. T25 was located immediately south of IV.17.2. This area had been disturbed and some ancient foundations destroyed by the construction of the fence along the modern highway. We found that the foundation of the southern wall of the nymphaeum was shuttered, not poured in to the sand. We also uncovered part of an east-west drain in the western portion of the trench.

The 2012 season marked our final large-scale excavations at the synagogue. Nine trenches (=T) were excavated in areas at least partially undisturbed by the 1960s campaigns in order both to better understand the stratigraphy of the present buildings and to explore evidence of earlier structures on this site. T27, located in Room 4 of IV.17.2, also extended 2.0 meters outside the west doorway. The soil outside the building was disturbed down to the level of ground water, but below topsoil in Room 4 was a mosaic floor (unexcavated, pending conservation). T29, located between IV.17.2 and IV.17.1, continued the examination of the western foundation uncovered in T23 (2011). Room 18 of IV.17.1 contained three trenches, each of which revealed a partially preserved cocciopesto surface below the topsoil. T32 was located in the SW corner. Its western wall was constructed on the cocciopesto floor, but the southern wall was deeply bedded. T31A was located in the middle of Room 18 extending from the northern wall. The foundation of the northern wall consists of a lower pour (an earlier building phase) and an upper pour (later). The upper foundation is integral with a N-S foundation, connected to another E-W foundation (possibly for low walls or for floor support). T31B extended from the west of T31A, revealing features associated architecturally with the lower level foundation of the northern walls, including a step and part of a reticulate wall. T34 was located in the southeast corner of Room 17 of IV.17.1. Two surfaces were uncovered: a cocciopesto surface below topsoil with a hole surrounding the opening of a decapitated Dressel 20 amphora. This surface rested on 0.75 meters of sand (into which the amphora was set), below which was a partially preserved cocciopesto floor. The trench exposed the foundations of the east wall which showed a clear seam, suggesting the mixtum A east wall is secondary. The lower cocciopesto floor was probably associated with an earlier structure represented by the lower foundation. In T30, located in Room 17 of IV.17.1, five distinct phases were identified. The lowest floor level (Phase 1) ran 0.60 meters below the latericium bedding course of the eastern wall, and the foundations were plastered. In the north, stairs were uncovered, ascending from the west in Phase 2 before the construction of the western wall. In the 3rd phase, two large amphorae were set into the floor (storage or latrine?). Phase 4 contained a latrine/drain construction in the space of the southern doorway (later covered by Phase 5, a floor covering all of Room 17). T33 was located in the open area east of IV.17.1. The predominant feature was a well-packed ground-raising fill containing numerous finds dating from 1st-2nd c. CE. T28, located to the north of the synagogue, revealed three layers of pavement spanning from the 3rd to the 6th cent. CE. T18BE (2011) was reopened to excavate beneath the robbed-out area of the Via Severiana. There were several preparation layers below the highway but no evidence of an earlier road.