The project aims to make use of the unique situation of the Constantinian Episcopal Church of Ostia: The architectural ensemble of basilica, atrium, presumed episcopium and later added baptistery will be archaeologically explored by stratigraphic excavations in its building typology and chronology, from its construction around 320 to its expansion in the late 4th and 5th centuries to its abandonment in the 8th century.

The Constantinian Episcopal Church at Ostia is a key monument for early Christian church building. Of all Constantine's church foundations, only the Ostian basilica was never reshaped by later buildings, so that it alone is available in its entirety for typological, architectural-historical and liturgical-historical questions. Moreover, it is the first example of a "standard" basilica that was built neither as an ex voto foundation nor as an architectural shrine around a venerated tomb or as a ceremonial church.

The Ostien Episcopal Church was discovered during an urbanistic research project with the help of geophysics and aerial photo analysis and subsequently verified by a few sondages, which is why it is only known in outline. Thereby the cathedral ensemble lies directly under the humus cover and can be investigated comprehensively. In the excerpted preliminary investigations, the unique potential became evident: abutting the Republican city wall and built over two older predecessor buildings, the original church ensemble also included a building south of the atrium, whose high-quality interior decoration suggests its function as an episcopium.

In the late 4th/early 5th century an independent baptistery was built, and from the later 5th century numerous burials were also placed in the atrium and church longhouse. From the 6th century on, the church was gradually abandoned and used for residential buildings, until the complex was finally abandoned in the 8th century. However, nothing is known about the integration of the complex into the existing street system, about the internal structure of the basilica, its architectural and liturgical decoration, the dynamics of building changes and their sequence. All these aspects can be clarified in stratigraphic excavation, whereby it is expected to answer not only fundamental questions about the building type and sequence, but also about the function as an episcopal, baptistery, and funeral church, about the conversion for residential use, and about the final abandonment.

These findings are a central piece of the puzzle for the (Christian) sacral topography of Ostia and processes of use and abandonment there, and are of exceptional importance for the understanding of Constantinian building policy and Late Antique Christian sacred architecture in general. In addition, the specific site situation promises new urbanistic insights into the long-term development of Ostia, from the late Republic to the early Middle Ages.

Duration: Since 2022

Promotion: Deutsche Forschungsgemeinschaft: DFG

Cooperations: Archäologisches Institut der Universität zu Köln (Prof. Dr. Michael Heinzelmann); Deutsches Archäologisches Institut Abteilung Rom (Dr. Norbert Zimmermann); Archäologischer Park Ostia Antica