In 2002, Peter Cornelius Claussen, then professor at the Universität Zürich, launched an ambitious, valuable project to analyze Roman church interiors of the Middle Ages. Over time, most of the churches have been modified, rebuilt, or restructured in such a way that their original interiors — pavements, liturgical arrangements, sculpture, portals, and use of various materials — have disappeared. They are often difficult to comprehend in their present-day context. In other cases, the buildings have been torn down, and only scarce documentary evidence testifies of their existence. The multi-volume Die Kirchen der Stadt Rom im Mittelalter 1050–1300 (2020) aims to reconstruct these interiors virtually through textual descriptions. Led by Claussen until his retirement in 2010, professors Carola Jäggi (Universität Zürich) and Daniela Mondini (Università della Suizzera Italiana, Mendrisio) continued this scholarship with Claussen until 2015, then later with other colleagues.

Much of the modern research on early Christian and medieval church architecture in Rome remains indebted to the foundational work of Richard Krautheimer. His Corpus Basilicarum Christianarum Romae (The Early Christian Basilicas of Rome) (1937–1977) and Rome: Profile of a City, 312–1308 remain essential for any serious scholar (Krautheimer 1977; Krautheimer 1980). The Corpus offers monographic studies based on archaeological evidence to foreground analyses and interpretations on the history of the architecture, whereas the single volume (Krautheimer 1980) represents Krautheimer’s view on the history of the architecture of Rome from early Christianity to the high Middle Ages. That said, research has not stopped with Krautheimer and his colleagues. More recent studies, such as those of Sible De Blaauw (1994), Ingo Herklotz (2000), Claussen (2008), and others have changed the way we consider new research questions, utilizing new methods and approaches in architectural history, and demonstrating the need for more data in considering the broader historical context.

Fortunately, Die Kirchen der Stadt Rom im Mittelalter does not present yet another art history of the Roman Middle Ages with its various, supposed stages of development; rather, the book seeks to reconstruct the ‘interior topography’ of medieval churches in Rome, which have been largely destroyed since the 16th century. This concerns the interior design and the spatial organization as well as the material remains of liturgical furniture. Claussen desired to underscore Roman culture of the Middle Ages as being independent from developments elsewhere in Europe usually labeled as Romanesque or Gothic. At the same time, the project’s systematic examination of churches in separate chapters results in an important contribution to the history of the sacred topography of Rome in the Middle Ages. The influences of diverse social groups on the making and development of these churches go beyond the pope and curial forces. Indeed, every church building was positioned in a situation of conflict within the community: the local nobility, religious orders, and the highest-ranking religious authority in the Roman curia each had to represent its own interests. The small church of Santa Maria in Cappella, for instance, was built by two cardinal-bishops in the late 11th century, San Marco still represents the basilica built by pope Gregory IV in the 9th century, and Santa Maria in Iulia initially seems to have been a convent for women around 800, which later went to the Templars. In a society where the visibility of positions communicated history and tradition, the formal language of church architecture and interior ornament was important.

As in Krautheimer’s Corpus, these volumes treat the churches across essays of differing lengths; within the fourth volume, the contributions range from two pages, for the church of Santa Maria in Cambiatoribus for example, to 138 pages, for the church of Santa Maria in Cosmedin. Even for scholars well versed in the architectural history of Rome’s churches, volume four offers new material and insights, showcasing the richness of the architectural history of the Middle Ages in Rome. It is a wonderful result of the whole series thus far that it indeed brings to life so many fascinating parts of the history of the large number of churches in Rome during the Middle Ages. One example is the number of churches, many of which still exist but are not very well known. Another element is the materiality of the buildings, showing a variety of colored marbles and granites both in the architecture and in the liturgical furniture.

This fourth volume of the project treats 37 churches with initial letters M, N and O; excluded are the churches of Santa Maria in Aracoeli, Santa Maria Maggiore, and Santa Maria in Trastevere, which, due to their significance and rich history, are to be examined at greater length in the project’s fifth volume. The entries on the individual churches have been written by a team of authors, mostly in German, with a few essays in Italian. The reader is immediately impressed by the sheer enormity of the task undertaken and the authors’ full embrace of the project. Although the entries differ in length, and even in choice of language, they are written in a manner that makes them complementary while retaining enough freedom to do justice to all the individual histories of the churches. Each opens with a description of the history and construction of the church in question, after which separate paragraphs are dedicated to specific elements of the building. Based on archaeological findings, written and visual sources, and where possible, remaining material evidence, the authors reconstruct the original interiors, with an eye as much for details as for the larger picture. Each entry concludes with a list of specific reference literature, and where necessary, there are also appendices with specific written source material. Quite often the histories are so complicated, detailing the different phases of construction and the realization of interior elements, including pavements and liturgical furniture, that the concluding summaries are very helpful. Since the book focuses on the Middle Ages, older construction histories are mentioned but not discussed at length. For Santa Maria Rotonda, or the Pantheon, the initial construction history of the ancient period is referenced, but more attention is given to the rededication in the early 7th century of the then-empty building as the church of Santa Maria. Apparently, soon after becoming pope in 608, Boniface IV started the process to turn the Pantheon into a church. Upon the pope’s request, the Byzantine emperor Phokas gave rich donations to the church. Phokas died in 610, giving Boniface the opportunity to assume complete control over the project. The complex history of the Pantheon’s portico justifies the 14 pages the author dedicates to the subject before entering the church to discuss its interior decoration. Changes from the antique temple to Christian sacred space were made without architectural changes to the interior, where the large yellow marble columns still dominate the circular wall layout. A large niche opposite the entrance, flanked by two large columns, became the liturgical center of the building by housing the main altar. Of the medieval ciborium only fragments remain.

In a volume of this size and breadth, there are innumerable decisions to be made in terms of the use of specific illustrations and the length and detail of given entries. Naturally, there are instances where the reader wishes for more material. A church like SS. Nereo ed Achilleo, for example, has such a complicated history of construction, rebuilding, and changes — all before its complete renovation in the 16th century — that the reader seeks more drawings than those that are included. For this fascinating church, the reader might be curious to know if any serious reconstruction has been attempted to show the galleries erected by Pope Leo III and how this structure compares to other contemporary gallery churches in Rome. Since the series of which this book is the fourth volume is aiming at the analysis and if possible the interpretation of the extant material in conjunction with written sources, not all contributions are steering towards a conclusion; the volume as a whole does not have a general conclusion either. The publication of the material is what matters here, and conclusions are left mostly to the readers.

Die Kirchen der Stadt Rom im Mittelalter’s ambitions highlight the rich interiors of Rome’s lost churches, with their opus sectile pavements, ciboria, ambo, Easter candlesticks, and mural paintings, which have largely disappeared over time. Recovering this important aspect of the history of churches in Rome in the Middle Ages is what is so valuable. The richness of the interiors, and the care that was taken to install the various liturgical arrangements and interior decorations in the different phases of medieval history, is staggering and underscores the importance of this publication project. In volume four alone, the reader digests fascinating material about a great body of spolia from Roman antiquity, pieces that were reused in the medieval church interiors. It shows how manifest the material history of Rome was in the Middle Ages, indeed leading to the development of a specific language of architecture and architectural interior decoration, which in medieval Rome remained quite distinct from developments elsewhere in Europe. A colorful variety of structural elements like marble and granite column shafts and wall revetments as well as pavements created the context in which the liturgical furnishing of many of these medieval churches was drawing the attention of the visitors. The most obvious exception in this cultural context of course lies in Santa Maria Sopra Minerva, which breaks away from the historical Roman context so often appropriated in other churches in medieval Rome. In Rome, the Gothic architecture of this church is an exception, which demands a thorough discussion of its history. Examining Santa Maria sopra Minerva, Almuth Klewin presents a clear overview of the construction history of this fascinating church, the architecture of which seems to have deliberately taken up non-Roman elements. In contrast to many other edifices, which used spolia to show connections with Roman history, there is no spolia in this church.

This fourth volume not only shows the abundance of Roman spolia that was reused in the Middle Ages but also explains the different reasons why such material was needed. The function of spolia played a distinct role in the minor pilgrim church of Santa Maria Annunziata (13th century), which stood along the route from the Abbey Tre Fontane to San Sebastiano. Probably the remains of an opus sectile-pavement of unknown origin were reused here and installed by workmen lacking expertise with such material. Likewise, Roman material remains conveyed a unique papal connection in Santa Maria in Cosmedin and underscored the legacy of Nicolas in San Nicola in Carcere. Several religious orders either directly or indirectly prompted the construction of a church like Santa Maria sopra Minerva or were closely connected to the building or the interior renovations, like Santa Maria del Popolo.

New in this volume is the section of color photographs, which prompts the question, why are there so few color illustrations? The bibliography at the end is very helpful, but the system is not that easy to understand. Each entry has its own bibliography of specific literature. Not all titles are included in the general bibliography, and there are also titles that appear only in footnotes. It is not easy to understand the rationale behind this system, and the present reviewer does not feel competent to explain it, but the persistent scholar will certainly find a rich body of valuable literature.

The 37 churches of Rome in the Middle Ages constitute a lot of fascinating material, and as part of the greater project, this 640-page volume demonstrates yet again how important it is to study the histories of construction, renovation, rebuilding, and restoration in conjunction with architectural interiors and liturgical arrangements. Even when nothing at all is known about the architecture of a given church, like Santa Maria in Cambiatoribus, it is valuable to devote a specific entry to the structure, if only to state that in written sources a ciborium is mentioned, which must have been part of a larger ensemble. The amount of work undertaken by authors and editors of this volume provide the readers with a wealth of information that will be very difficult to surpass. And the in-depth analysis of the buildings, with their construction and restoration histories, and of the remains, along with the documentation of the medieval interiors build the necessary tools for any historian of architecture, liturgy, and those interested in the life of so many spolia. This is not a book to read from cover to cover, but a volume to return to again and again.

Competing Interests

The author has no competing interests to declare.


Claussen, PC. 2008. Die Kirchen der Stadt Rom im Mittelalter 1050–1300. Band 2. S. Giovanni in Laterano. Stuttgart: Franz Steiner Verlag. DOI:

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