Sactuary of Isis and Magna Mater

About

The Sanctuary of Isis and Magna Mater in Roman Mogontiacum was built in the 1st century CE and remained in use until late antiquity. Archaeological remains came to light in 1999 during construction work in downtown Mainz for what is now the “Römerpassage”, and were subsequently uncovered in a rescue excavation. Plans to demolish the ancient walls after the excavations were completed were abandoned following public protests; instead, a display room was set up at the site, where the most important architectural remains and selected artifacts are presented in a permanent exhibition. A comprehensive monograph detailing the results of the excavation has not yet been published.

In the late 1990s, the postwar buildings of the Lotharpassage in Mainz came into focus for urban redevelopment. For the planned shopping arcade, then still known as “Lothar’s Passage,” the existing buildings were demolished and a large excavation pit was opened. The project was accompanied by the Office of Historic Preservation of the State of Rhineland-Palatinate (Mainz Branch). Since the Roman road leading from the legionary fortress to the Rhine bridge passed through this area—sections of it were uncovered during the excavations—a typical provincial Roman row-house development in half-timbered construction with small workshops was to be expected.

However, in late 1999, two unexpected discoveries of considerable significance were made at a depth of about five meters: the remains of a Roman sanctuary, which could be attributed to Isis Panthea and Magna Mater based on inscribed blocks, and, beneath it, a burial site from the Hallstatt period that was about 700 years older. Over the following 17 months, the ancient building complex of the sanctuary and the Iron Age grave were carefully excavated and documented. For archaeobotanical and archaeozoological analyses, 15 tonnes of soil were removed; in addition, 49 m³ of recovered material was collected. The work was completed in early 2001. A monographic publication on the excavation results is still pending.

At first, it had been intended to remove the exposed remains after documentation and continue construction of the shopping mall as planned. A similar fate had already befallen a Mithraeum in Ballplatz square from the 1st or 2nd century in the 1970s: uncovered during construction work, it was only inadequately archaeologically recorded and was ultimately destroyed. This time, however, protest emerged. In Mainz, a public debate flared up, and the newly founded initiative Römisches Mainz e. V. campaigned for the preservation of the sanctuary and collected around 20,000 signatures—an unmistakable vote against its destruction.

Public pressure was not without consequence. The ancient ruins of the sanctuary where permanently secured and integrated into the new mall. The public pressure did not go unnoticed. At the initiative’s suggestion, the shopping arcade was named “Römerpassage”—a proposal that initially met with considerable resistance in the municipal committees but ultimately prevailed. To proceed with the planned construction of the shopping mall façade, the remains had to be relocated: in a complex operation, part of the structural remnants was carefully dismantled and moved several metres, while the remainder was destroyed by the construction equipment. The preservation and relocation of the recovered remains cost approximately 3.5 million euros and were financed by the city of Mainz and the state of Rhineland-Palatinate. Since its opening on 30 August 2003, when approximately 25,000 visitors streamed into the city centre, the sanctuary remains have been open to the public in a presentation room in the basement of the Römerpassage as the “Taberna archaeologica.”

A glass walkway now runs around the exposed walls, while projections bring Isis and Magna Mater to life among the ancient foundations. Films, audio stations, and interactive elements complement the display cases containing the original finds. A staged ritual scene illustrates the daily practice of the cult; in an audio sequence, a fictional contemporary witness speaks about religious life in Roman Mainz in the 1st century CE. The space is kept deliberately dark in order to create a mystical atmosphere; small lamps set into the ceiling simulate the night sky of 21 December 69 CE. Information panels, along with a plan of the ancient city and of the sanctuary, complete the compact exhibition. On the occasion of its 20th anniversary, the sanctuary was designated “Museum of the Month October 2023” by the Rhineland-Palatinate Ministry of Culture.

Although Tacitus casually reports toward the end of the 1st century that among the Suebi the externally introduced Isis was venerated—while at the same time stating that he did not know the reason for this—this passage was long regarded as a misunderstanding, and the introduction of the Isis cult in Germania superior was dated at the earliest to the mid-2nd century. Although plausible arguments for the historicity of Tacitus’ statement had already been made before the discovery of the Mainz double sanctuary, it was only the discovery of the sanctuary that provided conclusive evidence for the early arrival of the cult in Upper Germania.

A fragment of a building inscription with an engraved tabula ansata attests to the construction of the sanctuary by the treasury administrator Primigenius, who was subordinate to a procurator of emperor Vespasian (AD 69–79). The unexpectedly large number of roof tiles discovered in the sanctuary that bear military stamps may likewise indicate a state-organized construction project, although the evidence remains inconclusive. In the inscription, the divine addressee is named only as [Mater] deum, by which Cybele is probably meant. Two related tabulae ansatae with nearly identical inscriptions, dedicated by an imperial freedwoman and an imperial slave or freedman under the priest Claudius Atticus, mention instead the Magna Mater and Isis Panthea. The two inscriptions can be dated to the late 1st century and are dedicated to the welfare of the emperor, the Senate and the people of Rome, as well as the army. The inclusion of the army is unusual and is likely due to a local context. On the basis of the aforementioned inscriptions, a direct connection between the earliest construction phase of the sanctuary and the imperial household has occasionally been postulated; however, the arguments advanced in support of this are not compelling.

The establishment of a double sanctuary for the Magna Mater and Isis under Vespasian has parallels in Italy. The inscriptions indicate that both dedications were performed by the same priest, suggesting a personal union of the priesthood. Archaeologically, several building phases can be distinguished. In the initial phase, there were small rectangular cult buildings within an enclosing wall, as well as several half-timbered structures with hearths. The latter presumably served as kitchens and assembly rooms for ritual banquets. In these cult dining facilities, the services were likely provided that ensured the economic sustainability of the sanctuary. In the 2nd century, the small cult buildings were replaced by a large, multi-part structure with a stone base, a half-timbered superstructure, and its own well chamber. The interior spaces were only sparsely decorated. The cult activities continued at least until the end of the 3rd century; in Late Antiquity, the structure was abandoned. Conclusions regarding the architectural development of the sanctuary can be drawn only to a limited extent, as the excavations did not expose the entire sacred precinct.

The precise position of the sanctuary of Isis and the Magna Mater within the sacred topography of Mainz cannot be determined with certainty, owing to the lack of other clearly localizable sanctuaries within the urban area. Nevertheless, the location of the sanctuary itself allows for some conclusions regarding the considerations that likely influenced its establishment. The sacred precinct was situated along a heavily frequented main road leading from the legionary camp to the Rhine bridge. It thus occupied an important traffic axis and held a highly visible position within the public space. The sanctuary was located within the civilian settlement, which was enclosed by a defensive wall after the mid-3rd century.

Despite its exposed location, however, central accessibility to major routes was probably not the decisive factor in the choice of site. Instead, there is much to suggest that the complex was deliberately established in close spatial proximity to significantly older burial mounds dating to the Hallstatt period, which were evidently still visible in the 1st century. Particularly revealing in this regard is the fact that the stone revetment of one such mound was not removed but rather incorporated into the new construction. Above the central grave, a masonry enclosure was created, which apparently served to receive burnt sacrificial offerings. It appears that when the sanctuary was built, there was a belief in the magical or sacred power of the site. For more information on this Hallstatt period grave, see below.

Access to the sanctuary was provided from the main road via a branching side path. Along this path stood small, simple buildings on both sides, constructed in timber-and-clay technique. Beyond this forecourt area lay the actual cult site, which was enclosed by a temenos wall and stood out clearly from the surrounding structures. Overall, the complex can thus be understood as consisting of two spatially and functionally distinct zones: a forecourt area with simple buildings and the actual walled sacred precinct.

The building history of the area proves to be extremely complex and confusing and is characterized by numerous alterations and extensions. The surviving architectural remains are overall comparatively modest and display a simple, at times even substandard, mode of construction, such as is otherwise only rarely attested in ancient Mainz. This is all the more surprising in that epigraphic evidence suggests a connection to the state administration. The numerous tiles bearing military stamps have likewise been interpreted as an indication of possible military involvement in the construction work; however, these apparently derive from secondary use and were employed, for example, to cover a larger burnt-offering complex. Consequently, they do not provide firm evidence for such a connection. It is possible that the architectural appearance preserved to us largely reflects a phase of the complex that was more privately oriented, whereas the original, more official part of the building has not survived.

In the earliest phase of construction, the sanctuary included a small temenos, which was later expanded. Within this walled enclosure stood two square structures measuring approximately 3.5 × 3.5 m and 4 × 4 m, as well as an adjacent shaft for receiving offerings. Given their similar size and shape, it is assumed that these two small buildings were each dedicated to one of the two deities worshipped there; the two tabulae ansatae were likely attached to them as well.

Later modifications significantly altered the appearance of the sanctuary. The original ensemble was abandoned, the temenos was redesigned and enlarged, and a larger building—which underwent frequent modifications over time—was attached to the older wall, ultimately taking on a symmetrical form measuring approximately 16 × 11 m. On one side, the structure was preceded by a well chamber, while on the opposite side several large wall blocks were situated. The interior comprised various rooms and functional areas, including two rooms of equal size surrounded by narrow corridors, as well as an access to the well along the central axis, which was later sealed. Very few decorative elements have survived. Remnants of wall plaster featuring simple panel paintings indicate a modest decorative style; figurative representations appear to have been limited to a few motifs. The only better-preserved image depicts Anubis holding a palm branch and a caduceus.

The floors of the sanctuary consisted solely of rammed earth; the roofs were mostly covered with tiles, though in some places they were covered only with wooden shingles. In the final building phase, a small rectangular structure was erected, with two large pedestals placed along its narrow side. This was apparently followed by a gradual decline of the complex; there is no evidence of violent destruction. Among the most recent settlement traces are several rows of postholes belonging to a building feature that has not yet been clearly interpreted and that cuts through all the earlier layers.

Within the temenos area enclosed by a perimeter wall, numerous features such as pits, ditches, fire spots, and accumulations of coal can be identified. These elements can be interpreted as material evidence of social activities and reflect both individual ritual acts and those performed collectively. The interpretation is not always clear-cut: for some individual findings, it remains unclear whether they represent intentional offerings or are part of layers of debris that accumulated during construction work or restructuring of the sanctuary.

Another problem arises from the fact that comparable findings also occur outside the enclosed area in the neighboring wood-and-mud structures, suggesting that similar practices were carried out beyond the cult precinct. Nevertheless, there are clear differences between the two areas, particularly in the range of finds. While cooking vessels dominate the outer area, eating and drinking vessels are less common, and the food remains differ both botanically and faunistically, with animal bones there predominantly found unburned. Together with the existing hearths, this suggests that the buildings in the outer area served primarily for the preparation and consumption of food, indicating use by communal dining groups. At the same time, however, traces of ritual activities can also be identified that go beyond purely secular use.

Some 300 lamps, often deposited in pairs on hearths used for burnt offerings, attest to the ritualized use of the sanctuary; larger oil lamps were probably part of its permanent furnishings. The central element of worship was the burnt-offering ritual, while permanent votive gifts played a secondary role. The composition and sequence of the sacrificial acts appear remarkably consistent across all phases of the sanctuary. The burnt offerings follow an almost standardized pattern: approximately 90 % of the animal bones derive from adult roosters, supplemented by songbirds, whereas other species are scarcely represented within the walled area. Complete dog skeletons as well as a detached dog skull were found in the pits and several cattle skulls were also recovered. Botanical remains show no single dominance, but pine nuts and cones, figs, dates, cereals, grapes, nuts, and legumes occur frequently. Oil lamps and coins are regularly found in the burnt debris, mostly without signs of fire. They were apparently deposited only after the burning; the lamps lying in the upper layers likely mark the ritual conclusion. The choice of type seems to have been irrelevant, whereas their integration into the ritual was essential. Variations in the size of the pits suggest differing numbers of participants, ranging from individuals to groups. Based on the material evidence, participants in the cult appear to have come from all social strata. For the beads made of rock crystal, other beads, and a fossilized ammonite found in the leveling layer, it remains unclear whether they are offerings from the Roman period or grave goods from the Hallstatt-period burials.

During the excavations, in addition to several votive stones and their fragments, a number of altars were also discovered. These epigraphic testimonies make it possible, on the one hand, to identify with certainty the deities to whom the sanctuary was dedicated, and on the other hand to draw conclusions about its dating. In contrast to the defixiones, the stone inscriptions have not yet been subjected to a comprehensive scholarly analysis of their texts and find contexts. Majuscule transcriptions of the building and dedication inscriptions, along with translations by Gerd Rupprecht and Géza Alföldy, can, however, be found in the exhibition catalogue Isis und Mater Magna ; moreover, they have been included in the Année Épigraphique.