David Karmon - Restoring the Ancient Water Supply System in Renaissance Rome

THE WATERS OF ROME, Occasional Papers, no. 3, JULY 2005

Aquae Urbis Romae: the Waters of the City of Rome

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® David Karmon


When the humanist Pier Paolo Vergerio recorded his first impressions of Rome in 1398, he described the legendary hills overlooking the Tiber as deserted, while the modern population clustered along the riverbank, erecting flimsy houses among the massive ancient remains.(1) Vergerio, familiar with the prosperous, orderly, mercantile towns of Padua and Florence, must have viewed the ramshackle sprawl of late-medieval Rome with fascination, and he made a pointed contrast between the imposing character of the archeological ruins and the insignificance of the modern constructions grafted onto them. He also observed the fundamental division between the abitato, the low-lying, densely-inhabited part of the city immediately adjacent to the Tiber, and the disabitato, the uninhabited, elevated regions beyond. This division would persist into the sixteenth century and was largely fixed by the range of the water-sellers, or acquarenari, who delivered water in barrels collected from the Tiber.(2) Because the higher land within the Aurelian Walls was beyond reach of the acquarenari and therefore without a steady water supply, it tended to be thinly populated. Vergerio’s observations, perhaps unintentionally, revealed the fundamental role played by water in shaping the post-classical city.

The only ancient aqueduct that continued to function in Renaissance Rome was the Acqua Vergine. It supplied water to the Trevi fountain at the foot of the Quirinal hill, and in turn the surrounding district remained populous, despite its relative distance from the Tiber.(3) Beginning in the fifteenth century, the Acqua Vergine became the object of new restoration efforts. The maintenance of the conduit was traditionally the prerogative of the civic administration on the Capitoline hill, but increasingly such work was also driven by the Popes, who used these public works to gain political advantages and reinforce their growing temporal authority. This article will investigate how the Renaissance repairs and maintenance of the Acqua Vergine were negotiated by these two poles of political power. Restoring the aqueducts allowed the city to flourish and expand, and perhaps more any other intervention epitomized the Renaissance revival of ancient Rome.

Ancient structure and design
In 19 BCE Agrippa completed the conduit of the new Aqua Virgo, the sixth aqueduct to be added to the network of aqueducts converging upon the capital.(4) According to legend, a maiden showed Agrippa’s soldiers to its underground spring at Salone, located about ten kilometers outside of Rome.(5) The Aqua Virgo, like most of the other conduits, originated on the eastern side of the Tiber valley, although its source was both slightly further north and closer to Rome than the others (Fig. 1). As the low elevation of the spring dictated the height of the system, the aqueduct could only reach the lower parts of Rome. The Virgo was thus perfectly suited to supply the new monuments projected by Agrippa for the low-lying Campus Martius, including the Baths of Agrippa, the artificial lake known as the Stagnum Agrippae, and the Euripus, a broad channel leading to the Tiber.(6)

The conduit traveled for most of its route below grade, following the Via Collatina and then the Via Praenestina, where the only sign of its presence was a short stretch of brick arcades across the occasional valley.(7) Before reaching Rome, the conduit turned abruptly north to circle the city before entering at its northern gate. This significant detour may have been imposed by property owners who refused to allow the construction of a more direct route, thus forcing the Virgo to travel through less populated districts.(8)

The conduit entered Rome below the western slope of the Pincian hill, under the present site of the Villa Medici. It traveled underground to the lower end of the present Via Gregoriana, where it emerged to continue its trajectory across the Campus Martius on elevated arcades.(9) Thus within the city walls the Aqua Virgo acquired a monumental presence: the conduit rode on top of more than one hundred arches, sometimes more than ten meters above the ground. These arcades, in contrast with the brick arcades outside the city walls, seem to have featured travertine construction.(10) Although the Aqua Virgo arcades ended near the present church of S Ignazio, excavations have revealed a distribution tank or castellum and lead piping that would have supplied water elsewhere in the Campus Martius.(11)

Numerous repairs were made to the Aqua Virgo in antiquity, as an essential source for the city water supply. It was restored under Tiberius, and then again under Claudius, after disruptions caused by Caligula’s building projects in the Campus Martius.(12) Further restorations to the aqueduct took place in the fourth century under Constantine.(13) As part of the Claudian rebuilding program, monumental arches were constructed to carry the aqueduct across principal roads in the Campus Martius. At least one such arch still stands today, at the Via del Nazareno, north of the present Trevi fountain, built with heavily rusticated travertine blocks (Fig. 2).(14)
A more elaborate triumphal arch carried the aqueduct across the Via Lata, the present Via del Corso, bearing inscriptions to commemorate the Roman conquest of Britain (Fig. 3).(15)

Above all, the longevity of the Aqua Virgo may be attributed to its submerged conduit, which made it less vulnerable to damage, and the renowned purity of its water supply. Nevertheless, the aqueduct still required regular maintenance; throughout its history, workers periodically descended into its channel or specus to repair damage and remove accumulated calcareous deposits to guarantee its continued operation.

Medieval history and repairs

The first major disruption to the Roman aqueduct system occurred during the attack of the Goths in 537 CE.(18) Evidently the damage was not catastrophic, for the system continued to function under the Byzantine administration. Significant restorations were again made in the eighth century under Hadrian I, providing enough water to satisfy “almost all of Rome.”(19) The peculiar advantages of the Aqua Virgo became apparent during this time of limited resources and political turbulence. The aqueduct was easier to maintain than any of the others, as it traveled only a short distance, and its submerged conduit was insulated from damage. Perhaps the most serious threat to its operation was the freeze-thaw cycle.

At the site where the Trevi now stands, the original channel turned abruptly west into the Campus Martius to avoid the Quirinal hill, forming an acute angle in the conduit.(20) This angle would be vulnerable to damage, and it is likely that the restorations of Hadrian I shortened the conduit to this point. The conduit beyond the Trevi fell into disuse, but its arcades long survived as a familiar landmark in the city; for example, the medieval Einsiedeln itinerary noted the fragmentary sections of the channel as “forma Virginis fracta.”(21) In the sixteenth century Andrea Fulvio noted many of the remains were still visible throughout the Campus Martius.(22)

The earliest records of the Capitoline administration that still survive expressed specific interest in the maintenance and care of the Aqua Virgo, or the Acqua Vergine as it was called in Italian, and the Trevi fountain.(23) Already in the new city statutes issued in 1363, six paragraphs were dedicated to the care and maintenance of the Acqua Vergine, to be administered by the marescalci curie capitolii, or the subordinate officials appointed by the Capitoline magistrates.(24) These officials were entrusted with supervising the conduit along its length from its entry point at the northern gate of Rome to the Trevi fountain.(25) They were also authorized to protect the conduit from secondary siphons and penalize all offenders.(26) The 1363 statutes expressly prohibited all unsanitary practices at the Trevi that might contaminate the water supply, such as bathing, washing animals, or laundry; the statutes further stipulated that all property owners who possessed spiragli or openings into the channel were responsible for sealing these openings to prevent their contamination by rainwater.(27) The extraordinary attention devoted to the care of the Acqua Vergine in the civic statutes emphasized its vital importance for the life of the medieval city.

Restoring the Acqua Vergine under Nicholas V in 1453

The 1414 map of Rome by Taddeo di Bartolo included the Trevi fountain among the city’s landmarks (Fig. 4).(28) The medieval fountain was evidently a simple rectangular structure, with three spouts pouring water into three basins. The fountain, aligned parallel to the route of the arcades behind it, faced west toward the Corso and the abitato. Although interventions by the civic administration ensured water continued to flow, the conduit became less efficient as it aged, and required constant patching and repairs.

The faltering aqueduct drew the attention of Nicholas V, who became the first Pope to sponsor the restoration of the system since the eighth century.(29) According to Giorgio Vasari, Leon Battista Alberti served as advisor for the papal intervention, which included not only repairs to the aqueduct channel, but which also transformed the appearance of the Trevi.(30) Whether Alberti willingly collaborated with Nicholas V on such large-scale projects redolent of papal absolutism is disputed.(31) Yet despite Alberti’s possible antipathy to the Pope’s political agenda, it seems quite likely that he would have been intrigued by these ambitious efforts to reshape the ancient capital. Further, he would have been uniquely qualified as a consultant for the work on the Acqua Vergine, given his research and knowledge of aqueducts as attested in the De re aedificatoria.(32)

Unfortunately, the Trevi restoration was only visually documented almost a century and a half later, by Tempesta in the map of 1593 (Fig. 5).(33) However, Tempesta indicated that the overall rectangular form of the fountain was essentially unchanged from the time of Taddeo di Bartolo. A single large water trough had replaced the three individual basins, and on the wall above the spouts, heraldic shields commemorated the repairs.(34)

The Franzini guidebook of 1643 showed Nicholas V’s fountain just before its demolition by Bernini (Fig. 6).(35) Despite the altered proportions, its overall form was still a plain fortified block. Franzini’s view also depicted the large dedicatory inscription and heraldic shields in much greater detail; the inscription, in austere Roman letters, proclaimed the Nicholas V’s role in restoring splendor to the ancient monuments of Rome.(36) The papal tiara and crossed keys crowned the inscription were flanked by two lower shields, each emblazoned with the “SPQR” insignia.

Such symbols allowed multiple readings through their arrangement and form. Although at first they might suggest the supremacy of the papacy over the civic government, Nicholas V was the only Pope to use the crossed keys as his personal arms; thus the papal shield could have been interpreted also as a sign of personal munificence.(37) The reference to lions in the fountain design was equally ambiguous. The lion was the heraldic symbol of the medieval Capitoline government, and thus the use of lion-head waterspouts could suggest the subordination of the civic government to papal will, but also its continuing responsibility as curator of the Acqua Vergine.(38)

Surviving documents provide only limited information regarding the extent of Nicholas V’s repairs. A papal payment of 200 ducats was made on 18 June 1453 to Pietro di Giuliano da Cholona for repairing the forma.(39) This term could refer to a portion of the channel, or to the entire aqueduct, or even the form of the Trevi itself.(40) Considering the rapid completion of the repairs, the restoration probably only affected the section of conduit nearest to Rome, perhaps extending as far as the Via Salaria.(41)

The restorations by Nicholas V must be viewed in light of contemporary events, as the papal capital experienced severe political upheavals in the early 1450s.(42) Stefano Porcari’s outspoken resistance to papal power fanned these tensions, and when he returned to Rome in 1453, defying a papal ban, he was swiftly captured and executed.(43) The repairs to the Trevi and the Acqua Vergine also took place in 1453, the same year as Porcari’s execution, a coincidence that invites speculation regarding possible political motivations underlying this papal restoration.

Certainly under Nicholas V papal power expanded into spheres previously controlled exclusively by the Capitoline administration. For example, as noted earlier, the 1363 statutes delegated the care and maintenance of the Acqua Vergine to the civic magistrates and their staff, also known as the maestri di strade.(44) However, in 1452 Nicholas V authorized an extensive revision of the maestri statutes, which subtracted these figures from the authority of the civic administration.(45) Although the new statutes reaffirmed that the maestri were responsible for monitoring the aqueduct, they were now firmly subject to papal authority; as the introductory paragraph declared, the office was newly organized and approved by the Pope.(46) The papal shield inscribed upon the official registers further underlined the new allegiance of these officials to papal authority.(47) By extending papal control over the maestri, Nicholas V undermined the autonomy of the civic government and gained control over important elements of the civic infrastructure, including the Acqua Vergine.

Nicholas V’s repairs to the Acqua Vergine also may have been calculated to benefit his supporters during this time of popular insurrection, and in particular the powerful Colonna family.(48) The church of SS Apostoli, the Colonna church, was restored in 1453, contemporary with the restoration of the Trevi. This ostensibly papal-funded restoration was actually financed using income from the sale of a large house near the Trevi, confiscated from one of the executed Porcari conspirators, to a Colonna prince. As Burroughs has observed, this “purchase...can have hardly occurred as a simple transaction on the open market.”(49) The restoration of the Acqua Vergine caused local property to gain rapidly in value, and thus the Colonna stood to benefit significantly from papal interventions at the Trevi. Even the workman hired for the Trevi project, Pietro Giuliano da Cholona, was probably a Colonna retainer.(50) Thus although the repairs to the Acqua Vergine publicly advertised Nicholas V’s concern for the general good, by rewarding local allies they also satisfied private political aims.

Collaborative papal-Capitoline administration of the Acqua Vergine
Yet the design of the Trevi fountain, in addition to its undeniable reference to Nicholas V, also indicated the continued presence of the Capitoline administration in maintaining the public utility. What were the reasons for suggesting this restoration was a shared collaborative venture between the Pope and the civic magistrates?

Nicholas V clearly had political incentives to favor an alliance with the Capitoline magistrates. In this time of extreme tension between the Pope and the leading citizenry, the Capitoline government offered the papacy a vital means to negotiate with the diverse social classes in the city.(51) Although the Porcari rebellion would be the last significant attempt to prevent the establishment of papal hegemony over the city of Rome, the design of papal-sponsored enterprises continued to publicize the alliance between the Popes and the civic government through the sixteenth century and beyond, undoubtedly intended as a reassuring sign of reconciliation and continuity between the two administrations.(52)

But Nicholas V also had practical reasons to support the traditional role of the civic magistrates as the curators of the Acqua Vergine. By 1453, the Conservators, the official title of the civic magistrates convening in the Palazzo dei Conservatori, had over a century of experience in maintaining the aqueduct system. As the aqueducts required diligent and constant care, the collective experience of the Capitoline administration represented an invaluable resource in the papal effort to increase the water supply for the growing city. As we will see, later Popes relied upon the civic magistrates to keep the system operational until the major institutional reforms of Pius V in 1570. Thus the conscientious presentation of the Trevi as a joint restoration had specific relevance in the context of Renaissance Rome. While the prominent heraldry emphasized the providential intervention of the Pope, it also acknowledged the indispensable contribution of the civic officials in supporting this essential service.

Papal interventions at the Acqua Vergine, 1466-1513
Despite the political significance of Nicholas V’s intervention at the Acqua Vergine, the physical function of the aqueduct was not greatly improved, and it soon required additional repairs. Work resumed on both the fountain and the conduit in 1466 under Paul II.(53) In preparation for the Jubilee of 1475, Sixtus IV repaired the arcades carrying the conduit to the Trevi, and cleaned the water channel.(54) In 1472 an ancient arch, perhaps a relic from the unused section of the Acqua Vergine, was demolished to provide travertine to build new aqueduct arcades.(55) The famous fresco of 1475 by Melozzo da Forlì celebrating the inauguration of the Vatican Library also celebrated the restoration of the Acqua Vergine, where the papal librarian Platina pointed to an inscription that listed the aqueduct among the greatest accomplishments of Sixtus IV’s pontificate.(56) Francesco Albertini, writing in 1510, noted that Pope Julius II also incurred substantial expenses on behalf of the aqueduct.(57) Julius II, as Sixtus IV’s nephew, had other motivations beside purely pragmatic reasons to repair the aqueduct, for continuing the works of Sixtus IV offered a means to perpetuate the memory of the Della Rovere dynasty in Rome.

Humanist interest in the Acqua Vergine, 1500-1515
As a surviving fragment of antiquity, the Acqua Vergine also attracted the attention of humanists in early sixteenth-century Rome. Andrea Fulvio observed that the aqueduct traveled directly through the gardens of the noted humanist and antiquarian, Angelo Colocci, and mentioned a stone structure with an inscription, probably referring to the Claudian arch standing to the north of the Trevi.(58) Colocci had purchased the surrounding property when he moved to Rome in 1513, and he established a villa and garden there that provided a setting for Pomponio Leto’s Roman academy.(59) Nourished by water from the ancient aqueduct, the garden evidently made a strong impression upon visiting humanists and scholars, who praised it in their poems and epigrams.(60) Scholarly presence also stimulated archeological research, and Colocci himself was among the first to identify the original source of the aqueduct at Salone.(61)

It seems Fra Giocondo may have found occasion to investigate the Acqua Vergine. It is quite possible that the famous Vitruvian scholar would have visited Colocci’s villa at the Acqua Vergine before his death in 1515, as Colocci expressed intense interest in his work, and a codex at the Vatican identified as Fra Giocondo’s is closely covered with Colocci’s notations.(62) Bartoli attributed a sheet of drawings with details from the Arch of Claudius to Fra Giocondo (Fig. 7).(63) The principal drawing, occupying the right-hand side of the sheet, documents the profile of the upper frieze and entablature of the arch, and its inscription.(64) Below, a small free-hand sketch depicts a portal flanked by two niches, set within a rusticated wall and crowned by the SPQR, and accompanied by a note indicating that this structure stood in the Colocci garden.(65) According to Bartoli, this small free-hand sketch represented an imaginary reconstruction of the Arch of Claudius.(66) However, the design, with its square openings and SPQR insignia, differs considerably from the design of the ancient aqueduct arch. Perhaps the sketch represented a gateway into Colocci’s garden? The caption implied that the garden was a familiar landmark, and it could well have featured a noteworthy entrance. Although the SPQR inscribed above the doorway could be a gratuitous antiquarian invention, it is equally plausible that it referred to Capitoline authority over the ancient aqueduct. The presence of such an inscription would be appropriate here, confirming the role of the Capitoline administration in supervising and maintaining the aqueduct system that supplied water to Colocci’s garden.

Capitoline supervision of the Acqua Vergine, 1513-1520
In 1513 Leo X issued a bull that authorized the Conservators to restore various civic structures, including the city’s aqueducts, using an allotted income derived from the tax on wine, the gabella studii. The income was to be used by the civic administration on behalf of improving the public appearance of Rome, including its walls, aqueducts, and bridges.(67) This tax had been used to subsidize civic services for almost a century, including repairs made by Sixtus IV to the Acqua Vergine.(68) Financing the repairs to the Acqua Vergine thus represented a collaborative process between the Pope and the civic magistrates, as funds dispensed by the Pope were then spent at the discretion of the Capitoline administration for the city’s public works.

Guaranteeing the supply of water to the Trevi fountain represented a significant challenge in the early sixteenth century, as the conduit was prey to siphoning by private property-owners. Andrea Fulvio noted that a network of unofficial feeder lines flourished along the conduit, diverting water to numerous adjacent houses and gardens.(69) The civic administration took steps to regulate and restrict such unauthorized use, as recorded in a document of June 1520, where the Conservators complained that water intended for the Trevi instead had been diverted to a garden belonging to Girolamo Gottifredi.(70) Apparently Gottifredi’s siphon reduced the fountain’s water level noticeably, and the Conservators decreed the channel should be immediately restored to its original condition. Although it is unclear whether this legislation was successfully enforced, the document suggests the Conservators continued to attempt to uphold their traditional role as curators of the civic water supply, and actively sought to control the amount of public water diverted to private use.

Paul III and restoring the Acqua Vergine to its original source, 1535
As demand for water from the ancient aqueduct continued to mount in the expanding papal capital, it became clear that a comprehensive restoration of the Acqua Vergine was necessary. While earlier restorations had focused only upon the section of the conduit nearest the city, by restoring the channel to its source at Salone the quantity and quality of the water supply could be greatly improved.

This major intervention seems to have received new impetus under Paul III.(71) During a session meeting in November 1535, when the civic magistrates were debating ways to spend an unusual surplus income, the Pope specifically encouraged them to use it for improvements to the Acqua Vergine.(72) Paul III’s interest may have been stimulated by a proposed renovation of the Acqua Vergine in an anonymous contemporary manuscript that has been attributed to the papal librarian, Agostino Steuco.(73) This text anticipated that the rehabilitated conduit would supply a splendid spectacle in the form of three new fountains along the Via del Corso (renamed the Via Paolina), celebrating the munificence of Paul III.(74) It has been observed that this particular proposal was not technically possible, for it envisioned a route over the Pincio that was beyond the capacity of the low-level Acqua Vergine system.(75) But such a proposal may have attracted the Pope’s attention, and encouraged him to consider such a restoration.

Yet this restoration would be sidelined by the triumph of Charles V in 1536. Returning from his victory at Tunis, Charles V would enter Rome from the south, thus redirecting Paul III’s attention to the other side of the city, so that preparations for a triumphal route from the Porta di San Sebastiano into the Forum now dominated the papal agenda. The restoration of the Acqua Vergine thus would be postponed for another generation.(76)

Continued decline of the Acqua Vergine, 1548-1570
Toward the end of Paul III’s reign, the deferred maintenance of the aqueduct had reduced the water supply at the Trevi to a trickle. In his 1548 guidebook to Rome, Lucio Fauno described the Acqua Vergine as ruined and providing hardly any water.(77) The progressive deterioration of the conduit in these years must also in part be ascribed to the limited resources of the Capitoline administration. Without financial support from the Pope, the civic magistrates were unable to conduct necessary maintenance; however, they periodically continued to assess its condition. In a session of 1550, the Conservators observed that if no preventative measures were taken, the ruinous state of the channel and abusive feeder lines would reduce the water supply to nothing.(78) The reference to abusive feeder lines was probably a thinly-disguised criticism of Pope Julius III, who had just erected his new Villa Giulia, with convenient access to the Vergine conduit, outside the northern gate to the city.(79) The remarkable waterworks of the immense villa, including the fountain at its entrance (Fig. 8), must have strained the capacity of the halting Acqua Vergine to the limit. Yet this deprivation evidently was not important enough to attract papal interest, for it seems that restoration only began after water did in fact cease to flow into the Trevi in 1559.(80)

Pius IV authorized funding for the restoration of the ancient conduit to its original spring on 3 June 1561.(81) The project naturally received full support from the Conservators, but as the restoration advanced, disagreements emerged between the civic magistrates and the clerical authorities.(82) The Pope and the commission of cardinals appointed to supervise the water system often overruled the Conservators in the process of expanding the aqueduct network, despite the accumulated knowledge and experience of the civic magistrates.(83)

However, the reliance of the Conservators upon papal largesse meant their bargaining power was limited, as revealed by their discussion of a malaria epidemic in 1567 caused by stagnant water leaking from the Acqua Vergine. First the Conservators declared, since the care and conservation of public works was their fundamental duty, that a permanent custodian should be appointed to the Trevi to prevent any such future disasters. Then they observed that the salary of the custodian would be disbursed by the general treasurer of the Camera apostolica, as all such officials were paid.(84) Clearly, despite their vocal defense of public utilities, the Conservators needed papal revenues to maintain these systems, let alone conduct any major renovations.

By the time the Acqua Vergine conduit was completely restored to Salone in 1570, the authority of the civic magistrates over the aqueduct was swiftly evaporating.(85) Already in 1567 Pius V had created the new institution of the Congregazione cardinalizia to transfer the administration of the Acqua Vergine to ecclesiastical hands. Finally, in 1597, a clerical administration headed by a soprintendente dell’Acqua Vergine took over its operation.(86) The ancient privileges of the civic magistrates were annulled, and the Acqua Vergine was incorporated into the expanding papal water-supply network.(87) Yet if the Congregazione provided more efficient and centralized control over the city’s water supply, it also inherited a long-established tradition, assuming the time-honored role of the civic magistrates as the official advocate of the Roman aqueducts.

Pirro Ligorio’s study of the Acqua Vergine conduit, 1550-1565
The writings of the antiquarian Pirro Ligorio offer a useful source for the study of ancient Roman remains and their afterlife in the Renaissance.(88) Ligorio examined the history and construction of the Acqua Vergine in detail in the sixteenth volume of his encyclopedic dictionary, the Libri delle antichità, composed between 1550 and 1565.(89) In this volume, Ligorio described the different building construction techniques that marked the Acqua Vergine as it emerged from the source and traveled through underground conduits and across arcades in its path toward Rome.(90)

Ligorio’s careful archeological analysis permitted him to evaluate and criticize the quality of the aqueduct’s construction techniques. In particular, the sections of the aqueduct exposed above ground attracted his attention. Although the channel itself was of solid construction, he observed that the supporting arcaded structure was molto debilmente fabricata, or very poorly built. He further investigated these architectural weaknesses in a series of drawings, where he reconstructed its restoration history.

Ligorio’s first drawing showed thirteen brick arches spanning a valley, near Portonaccio, at Maranella, where the Acqua Vergine turned away from its westbound course to travel north around the city (Fig. 9).(91) After a digression regarding the Arch of Claudius in the Campus Martius, Ligorio described the fragile condition of the ancient conduit, noting that the ancient Romans, in a misguided effort to stabilize the arcades, had filled them in with opus reticulatum. He concluded with the admonition that the history of this structure should persuade modern builders to build strong and durable works rather than fragile ones.(92)

Ligorio accompanied this discussion with two drawings of the restored aqueduct (Fig. 10). These drawings depicted the two phases of the restoration conducted by the ancient Romans. In the upper drawing, Ligorio how showed opus reticulatum was installed to shore up the supporting arches. Then, in the lower drawing, he showed the new buttresses built as a later restoration, adjoining the original brick piers in the attempt to reinforce the structure. In his commentary he noted the new buttresses were not integrated into the original piers, and thus allowed shrubs to take root in the gaps and causing even greater damage.(93)

Ligorio’s analysis is extremely valuable as an early effort to distinguish between different phases in a building’s history. He demonstrated a new archeological awareness of historical change and the impact of restoration interventions upon an existing structure. The Renaissance sensitivity to different building phases had been first clearly articulated in the Letter to Leo X, where Raphael judged the quality of the different components making up the Arch of Constantine.(94) However, where Raphael’s judgments were based upon style, Ligorio’s judgments were based on function. By differentiating between the individual interventions, Ligorio observed that badly-conceived restorations could have a deleterious effect. While the first restoration of the arcades had failed to accomplish its purpose, the second restoration imperiled the structural integrity of the entire aqueduct. Ligorio’s investigation revealed such close archeological examination offered essential guidance in conceiving and conducting repairs to historic structures.

The Arch of Claudius on the Via Lata

As noted above, Ligorio also discussed the Arch of Claudius in the Libri dell’antichità. His commentary regarding the sixteenth-century fate of this structure evokes the problems of monitoring archeological remains in sixteenth-century Rome.(95) Although the Arch of Claudius was demolished in late antiquity, substantial remains survived into the Renaissance.(96) Ligorio provided a reconstruction showing a richly decorated structure, with a high attic storey carrying a dedicatory inscription and the conduit behind (Fig. 3). In his commentary, he lamented that recently many of the surviving fragments had been excavated and sold for reuse; apparently here Ligorio was speaking from bitter personal experience.(97) Pius IV had evidently appointed him with the official responsibility of protecting the ancient remains; perhaps he may have served as a papal Commissioner of Antiquities.(98) However, in this case he was unable to enforce any protective restrictions, as both he and his associates apparently received death threats if they made any attempt to stop the illegal excavation and sale of archeological remains.(99)

Ligorio’s melodramatic brush with the underworld commerce in ancient remains underlines the fact that the illicit antiquities market had firmly taken root in sixteenth-century Rome. His discussion reveals with unusual clarity the daunting challenges confronting those who sought to impose protective measures. The concern for preserving archeological remains was limited to a small number of antiquarians, and this fact, compounded by the value of ancient remains on the international market, made protection exceedingly difficult. Thus Ligorio painted a gloomy picture for sixteenth-century conservation efforts. Even when papal policy overtly favored the protection of the enormous archeological patrimony of Rome, many fragments, such as the Arch of Claudius, still vanished in the burgeoning antiquarian trade.

Although the themes of spoliation and destruction dominate the history of ancient monuments in post-classical Rome, the history of the Acqua Vergine reminds us that some ancient structures not only survived, but were even actively restored during the Renaissance. Between 1453 and 1570, the derelict aqueduct channel experienced an extraordinary transformation, recreated as a modern water system to rival its condition in antiquity. Obviously, those ancient structures which provided vital services received first priority; while the part of the conduit remaining in use was the focus of numerous protective interventions, the abandoned section, including the Arch of Claudius, would almost entirely vanish by the end of the sixteenth century.

Perhaps the most remarkable aspect of the Acqua Vergine’s Renaissance history is the manner in which the care of the ancient monuments could be negotiated in this tumultuous time of demolition and change. As the foregoing argument has sought to demonstrate, important archeological remains survived through the combined efforts of both papal and civic institutions. These two powers were often rivals with very different political agendas and strategies, yet their competitive relationship actually contributed in a vital way to the preservation of the ancient past. Such patterns become apparent in the history of the Acqua Vergine, where the joint interventions of the Popes and the civic magistrates ensured that the water of ancient Rome’s one surviving aqueduct continued to flow.