This excellent monograph is a history of the Forum Romanum from the late-third to the late-fifth centuries a.d. Drawing on evidence from archaeology, epigraphy and literary texts, K. reconstructs the changing physical appearance of the most important public space in the Later Roman Empire. The book is beautifully produced. More than 200 illustrations (including maps, photographs and digital reconstructions) enable readers to consider in detail the evidence on which K.'s conclusions are based. But this monograph contains much more than a lavishly illustrated catalogue raisonnée of late-antique structures in the Forum. K.'s primary concern is to recover the changing meaning of the construction and reconstruction works carried out on the site. The ways in which the monuments in the Forum were perceived never remained the same. Rather, with each new intervention in the urban fabric, older structures obtained a new significance: the Forum was ‘a text that was constantly under revision’ (p. 18). It is through his subtle exploration of the meaning of construction and restoration works in the Forum that K. makes his most significant contribution to scholarship.

K.'s book falls into two halves. The first maps the ways in which successive emperors inscribed their presence in Roman public space: Chapter 1 contains an analysis of the radical transformations of the Forum initiated by Diocletian and his co-rulers, Chapter 2 looks at the impact of Constantine and Chapter 3 traces the monumental footprint left by later fourth- and fifth-century rulers. The latter half of the book analyses the activities of Roman senators and Christian bishops in the Forum: Chapter 4 explores the transfer and restoration of statues by urban prefects, Chapter 5 deals with the preservation of pagan temples and their redefinition as symbols of classical culture, and Chapter 6 is a close reading of the meaning of several new administrative buildings which emerged around the senate-building in Late Antiquity.

There are many virtues to this book. An early highlight is K.'s clever reinterpretation of the two five-column monuments constructed by the Tetrarchs. These massive structures, more than 12 m high and topped by porphyry statues of Diocletian, his three co-rulers and their respective guardian deities, towered high above the late-antique Forum. K. subtly situates these constructions in the larger context of Tetrarchic ideology. He argues that they communicated a new concept of cyclical time, in which groups of legitimate rulers followed each other at regular and fixed intervals: ‘The two groupings of five figures elevated upon columns from the two facing Rostra at either end of the Forum depicted the alternation from one Tetrarchic college to another’ (p. 42).

The Constantinian redesign of the Forum is handled with similar skill. K. argues that the interventions in urban space by Constantine and his followers entailed a rejection of Tetrarchic ideas of time. By refurbishing buildings constructed by his followers with spolia, the emperor and his advisers staked out a claim that the new regime was more than merely a continuation of the past. Rather, his reign constituted an improvement of earlier reigns: ‘The connected ideas of restoring and reforming were communicated by Constantine's projects at the Forum, which revised attitudes toward the past while maintaining the city's heritage’ (p. 74). The same idea of the Constantinian regime as an amendment of the past was communicated by portrait statuary. The equestrian monuments of Constantine and his sons, situated in the Forum square, constituted a deliberate and provocative departure from the tall column-monuments set up by the Tetrarchs. In retrospect, the new statuary made Diocletian and his co-rulers looked threatening and aloof. But of course, in time, new structures would also give the monumental heritage of the Constantinian dynasty a new meaning. For example, the triple set of portrait statues set up for the emperors Valentinian II, Theodosius, Arcadius and their female ancestor Thermantia was carefully calculated to highlight the contrast with the nearby triple monument for Constantius II: ‘Viewers were invited to appreciate the Theodosians as closer to the people, less self-aggrandizing, and more attentive to their matriarch than was Constantius II’ (p. 89).

Another strength of the book is K.'s subtle treatment of the meaning of spolia. When emperors and their officials employed materials from old buildings for their construction and restoration works, this was never just a cost-cutting measure. Rather, spolia changed the meaning of the structures of which they formed part. I particularly liked K.'s interpretation of the restoration of the temple of the Dei Consentes by the famous pagan aristocrat Praetextatus. On the one hand, Praetextatus moved images of the twelve gods from the interior of the building (where the now prohibited sacrifices had once taken place) into the exterior (where they could be appreciated as artworks by pagans and Christians alike). On the other hand, he renovated the walls of the temple by using ‘purposefully mismatched columns and capitals’ from older buildings. By employing spolia for this purpose, Praetextatus sought not to conceal but to highlight the identity of the temple as a renovated structure: the ‘explicitly excerpted fragments indicate that Praetextatus revised temple architecture, its formats, and its meanings’ (p. 132). K. argues that this deliberate emphasis on the gap which separated the present from the past obtained particular significance in a period when traditional cult practices came under attack. It enabled Christians to see this building not as the religious structure as which it had once served, but as a civic amenity.

I have one disagreement. In Chapter 5, K. assembles a great deal of useful evidence on the refurbishment and transfer of statuary by urban prefects. He convincingly demonstrates the concern of the leading imperial officials in the city for the preservation of Rome's cultural heritage. K. claims that the restoration of statues was a subtle act of resistance against the emperors: ‘Senators moved statues to the facades of the Basilica Aemilia and the Basilica Julia to launch an implied critique of the imperial displays elsewhere in the Forum’ (p. 124). Here K. goes too far. Significantly, almost all these inscriptions carefully record that the restorations were carried out by the urban prefect, the senior imperial official in Rome. Most likely, they were financed by imperial tax-revenues. The fact that the senior imperial official in Rome invested public funds not only in political displays in the centre square but also in the restoration of artworks in basilicas can hardly have been taken by contemporary onlookers as a subtle criticism of the imperial monarch. Notably, emperors in their legislation repeatedly encouraged their officials to restore old monuments rather than construct new ones. Far from expressing a ‘critique’ of the imperial government, these displays symbolised the shared concern by the emperor and his top administrator in Rome for the maintenance of the city's monumental heritage.

This is not to claim that emperors and aristocrats always had the same ideological priorities. Open defiance towards the imperial government is advertised in a well-known inscription from the Campus Martius, which records the restoration of a mithraeum by an aristocrat named Tamesius Olympius after the removal of state funding for the traditional cults: sumptusque tuos nec, Roma, requirit (CIL VI 754). Significantly, however, Olympius came from a middling senatorial family and seems to have held no imperial office. He could afford to advertise his opposition to imperial policy. Urban prefects and other prominent members of the aristocracy (whose honour and wealth critically depended on maintaining cordial relations with the imperial court) could not.

But such differences in emphasis should not detract from the value of this book. By exposing the full complexity of restoration as a cultural practice, K. makes a significant contribution to our understanding of late-antique public space. This book should be read not only by specialists of the Forum but by all historians and archaeologists interested in the urban history of late-antique Rome.