Any recent visitor to Rome would agree: a shared understanding of environmental hazards, deep insights into how to sustain a large urban population, and the availability of relevant technologies are insufficient prerequisites for keeping the city clean. And what is tragically true in 2019 was no less evident to Rome's denizens in earlier eras. Pamela O. Long demonstrates for the later sixteenth century that consensus was simple enough to reach concerning the importance of clean air and water, wide and paved streets, proud Christian(ized) monuments, and a pious, disciplined population. Yet serious obstacles stood in the way of realizing any of it: the humongous costs involved in creating, restoring, and policing infrastructures; conflicting political agendas among the religious and secular elites governing Rome; and the limited technical and logistical competence required to carry out grand urban projects, often exacerbated by corruption and professional rivalries. There were also some externally inflicted setbacks, not least among them the city's sack in 1527 and especially the Tiber's massive flooding in 1557, which claimed a thousand lives and signaled to Rome's dense and mostly low-lying population how vulnerable the Eternal City really was.

For a period and a city all too often celebrated for their intellectual, political, and material achievements, Long's injection of contingency is a breath of fresh air. It is easy to forget at what exorbitant cost (and popular outrage) some of the city's present-day monuments were erected, at what shocking inefficiency, and with what limited benefits to the population as a whole. As seen through Long's lens, the new Christian urbanism of the post-Tridentine era was a story of (at best) intermittent success, undermined by popes’ resolve to undo or outdo their predecessors’ legacies in a material sense and the lack of regular budgets and stable bureaucratic structures to run the city proactively. It is unclear, however, to what extent Long thinks that the latter situation was unique to Rome, perennially true, or an outcome of recent political and demographic events. After all, salaried infrastructure specialists such as roads officials (viarii) had been active in Rome and in numerous cities across the peninsula (whence many of the city's architects and engineers hailed) since at least the thirteenth century. And there is abundant evidence for their preventative and reactive efforts to keep cities decorous and clean during centuries in which urban populations and networks were rapidly growing.

Long's challenges to a popular view of late Renaissance Rome concentrate in chapters 1–4 and 7, which deal with programs to improve drainage, streets and aqueducts, and human and animal behaviors in these sites. Based on detailed archival records, narrative accounts, maps, prints, and archaeological data, she ably reconstructs the trials and errors of urban magistrates’ attempts to protect the urban environment and update its infrastructure using abandoned devices and sometimes by creating new ones. Although the humoral-Galenic paradigm informing preventative health programs had scarcely changed since late antiquity, the author convincingly shows how a new kind of curiosity about past structures, from a mathematical as well as aesthetic perspective, intensified and diversified their (re)integration into the city's fabric.

This new intellectual vigor, along with the tensions it summoned, is even more present in chapters 5, 6, and 8, which concern efforts to map and beautify Rome using its ancient material heritage as well as techniques said to derive from (and even improve on) Greek and Roman science. The tenor in these pages tends to be somewhat more celebratory than in other chapters and is richly illustrated by designs, themselves a product of new and sophisticated etching and printing techniques, for which Rome has become justly famous. Long rightly warns against seeing the ambitious men recruited by the papal court and communal government as modern-day professional engineers, architects, or urban planners. Indeed, it was precisely their lack of specialization (or what we may call interdisciplinarity) that led them to attempt (and sometimes fail) to rebuild Rome.

In sum, Engineering the Eternal City is a very readable account of three dynamic decades in Rome's material and intellectual history, which resists a teleological narrative of the city's urbanistic success, on the one hand, while illustrating the benefits of a multidisciplinary approach on the other.