From the time of its mythical founding in the mid-eighth century B.C.E. and for the next 500 years, Rome expanded its living and working spaces across its hills and valleys and, with a seasonal rhythm, ventured beyond its protected position to confront and defeat other tribes throughout the Italian Peninsula. A large swath of real estate just to the north of Rome's walls remained, however, in its natural state, unconquered and untamed. While other low-lying portions of Rome were drained and built upon, the area between the Tiber and the Pincian and Quirinal Hills stayed a swampy, mosquito-infested clearing to which citizens came periodically to muster for military exercises, to be counted in the census and to vote, and, at the far southern end, to shop at a vegetable market. The natural and austere conditions of the marshland for that half millennium suited perfectly the needs of a growing military power that required a large unencumbered space in which to gather and train its troops. Religious and very practical social policies forbade armed soldiers to cross the sacred line or pomerium and to enter the urbis, except in the event of a military triumph. When awarded a parade for valor in battle, a consul would gather his troops in the northern field to march into the city with captives and booty. The populace could be counted in the plain while protected by the army, and the surrounding hills provided excellent observation points for all to be carefully watched. It mattered little that the marshland flooded in the winter or was infested in the summer, as the designated activities generally could be timed to avoid those issues.
Used for centuries as a location to prepare for battle and triumphal parades, the campus developed early associations with Rome's god of war, Mars. Horses raced across the plain in his honor in the spring and in the fall, while on the Ides of March, the deity's eponymous month, revelers raced to the area to celebrate the New Year. An altar to Mars was constructed there, and by the mid- to late first century B.C.E., writers were referring to that portion of the field west of the Via Flaminia as the Campus Martius. When the myths of Rome's founding by a son of Mars, Romulus, were developed in the early third century B.C.E., it was the northern flatland that was selected as the site of the ruler's apotheosis. The anniversary of this event was celebrated with running and shouting, mock battles, and dining in the campus. In another myth, the republic was said to have been founded upon the seizure of the last king's grain growing there. The stalks were tossed into the plain's watery western boundary, and when captured by the rocks at the southern end, the accumulated grasses helped create the Tiber Island.
As the myths linking the Campus Martius to Rome's foundation were emerging, the military imperative to maintain the real estate in its natural environment was diminishing. In the 100-year period from the mid-third to the mid-second centuries B.C.E., the era of the three Punic Wars, Rome began to send its troops far from the Italian mainland and for more than seasonal duty. With reduced use by the military, the field beckoned for development. At first only permanent structures deemed consistent with its mythical and martial past, namely victory monuments, were erected. Consuls in the heat of battle prayed to gods. Returning victoriously to Rome, they honored the solicited deity with a temple. Approximately half of all temples vowed during the century of Punic Wars were located in the Field of Mars. If the open plain north of the city was deemed sacred to Mars, such “sacredness” certainly did not hinder its development; if anything, it encouraged it.
Placed in three large nodes where they could be admired during the gatherings of the census or at the collection point for triumphal parades, these temples, ostentatiously endowed with statuary and other symbols of foreign conquest, brought honor to their patrons and to the city. Two of those areas, the Circus Flaminius and the Forum Holitorium, became better defined by the temples erected along the edges of each. During the same period, the Via Flaminia cut through the heart of the plain, establishing thereafter the campus's eastern line and facilitating both military and commercial travel from the city walls to the northern horizon. Porticoes employed as ceremonial walkways or embellishments to sacred precincts made their debut in Rome during this period, finding their first expression in the northern plain. As the space was beyond the pomerium, the Field of Mars was still an important location for soldiers to form up for triumphal parades, for foreign ambassadors to await the right to enter the city and for citizens to vote and to be counted in the census. There was still ample room for these activities, and the placement of temples and porticoes was clearly made with those continuing functions in mind.
It does appear evident from the ancient sources that a certain level of architectural experimentation was undertaken in the republican structures erected in the Field of Mars. Captivated by the building design and decoration seen in their forays to the East, Rome's generals used the marshy soil of the Campus Martius as test plots to develop these architectural forms that then took root throughout the city. At first, Greek elements were grafted to the older Etruscan styles. Later, other eastern architectural elements found their initial expression in the northern plain with the first structure in the city made entirely of marble and the first victory monument in Rome to be fashioned in the form of a colonnade. A confluence of factors likely explains the choice of the Campus Martius for the exploitation of new architectural forms, but certainly the location of the space beyond the pomerial line may have afforded license to challenge the traditional forms in a way that was not possible within the city proper.
Topography played an indirect role in temple construction in the Campus Martius in the sense that the open flat plain was well suited for the periodic large public gatherings, and the builders of such structures would want to place them in close proximity to those sites. It did not appear to place great constraints, however, on the orientation and relationship of the temples as the wide plain allowed the three primary nodes to develop without clear reference to each other. The Circus Flaminius ran from the southeast to the northwest, roughly following the line of the Tiber at that point, and the temples around it were oriented toward the center of the space. The temples in the Largo Argentina faced due east in the direction of the morning sun and the nearby Villa Publica. The temples in the Forum Holitorium opened to the northeast, far to the south of the Largo Argentina. If they communicated at all, it was in the shared themes of military glory and as possible way stations on the triumphal parade route. The buildings themselves did little to alter the topography and did not likely disrupt the prior rhythm of popular use of the space. Rome's residents flocked to the Campus Martius for holidays and special events; the temples were embellishments and would not have changed the established activities that occurred in the field.
In the mid-first century B.C.E., topography played a more central role in the site determination of more grandiose buildings, and these, in turn, altered both the landscape and the uses of the Field of Mars. Until that time, theatrical performances were held in the campus near temples as part of religious festivals as well as in large temporary theaters. With respect to the latter venues, space within the city walls was at a premium in the middle to late republican period, and a wooden stage could be erected on a temporary basis in the Field of Mars without much effort and removed just as easily when its presence was deemed offensive to the public good. When objection to permanent theatrical structures waned in the late republic, the flat space of the Campus Martius was perfect for creating a new form of freestanding entertainment site. It was here that Pompey the Great erected Rome's first permanent stone theater. Engineered to withstand massive loads above marshy soil and employing materials impervious to rising floodwaters, the theater met and withstood the challenges of building in the Campus Martius. Constructed beyond the city walls, the theater did not require the demolition of existing structures, an issue that could provoke political backlash. It was also raised at a time and place that lessened the risk for criticism, although Pompey's effort still had its detractors.
The theater's construction in the plain was transformative. At about the same height as the Capitoline and more than half its area, Pompey's enormous stone structure was a “veritable mountain,” and with its appended quadriportico it dominated the Field of Mars like no previous building and like very few since.1 Its size, significance, and uses, as well as the authority of its builder, created its own gravity that soon drew other large structures in its direction and oriented them on an orthogonal grid. For the first time, the Field of Mars had an attraction that gave Rome's populace a reason to venture north of the pomerium. Now, the city's inhabitants came frequently and in large numbers for entertainment and relaxation in beautiful gardens. The Campus Martius was no longer simply a site at which to practice for war or honor victors or past victories. It was a magnet for quotidian pleasures.
Built as the republic was in its death throes and before the empire arose, the theater's construction in the plain was also transitional. Located close to one of the established republican temple nodes, the theater also carried on its shoulders a series of religious spaces, but its size and function presaged the many large utilitarian and secular spaces to be developed there by the emperors. Its chronological and physical positions in the development of the northern marshland as well as its architecture allowed Pompey's theater to serve as a bridge between the republican past and the imperial future of the Field of Mars.
There was, however, one other general with the prestige and financial means to equal if not best Pompey in construction in the Campus Martius, and he had the plans to do so. Julius Caesar built a basin for the similacra of sea battles, cleared land for atheater, and proposed a new voting precinct, the Saepta. He even conceived the idea of shifting the Tiber west to add more land to the northern field. None of these projects save the naumachia, however, was ever brought to fruition by Caesar. Instead (ironically), he died in an annex to Pompey's own portico structure, and his dreams for the plain were not to be realized for at least another decade, when his heir Octavian, fresh from his victory over Mark Antony, turned his attention to the northern field.
Octavian, the future Augustus, tackled the Campus Martius from three different directions and, in a sense, in three different ways. On the northern narrow throat where all must pass along the important Via Flaminia, he built his mausoleum. It was as high as Pompey's theater and with its surrounding parks challenged it for dominance of the plain. As a burial site, its extrapomerial location was appropriate, and its massive structure countered the “gravity” of the Theater of Pompey. At the far southern end of the plain, the Augustan theater dedicated to Marcellus counterbalanced the mausoleum, and like Pompey's theater, it helped anchor traditional republican temple nodes, resting between and dominating the Circus Flaminius and Forum Holitorium. As the mausoleum provided a very visible demarcation to the northern edge of the Campus Martius, the Theater of Marcellus was similarly sited at the southern end. Indeed, Augustus became the gatekeeper with respect to triumphal parades moving south. No longer could such spectacles move through the Circus Flaminius to the city gates without first going through his family's theater. The emperor's improvements in that area did not stop with the theater, however. Temples were rebuilt and expanded with libraries and new porticoes added. Statues to the deified Augustus were erected there, as well as later an arch to the deceased Germanicus. The symbols of Augustan power were everywhere, and the individualized monuments to a republican past were transformed into a unified glorification of an imperial present.
It was in the central Campus Martius that Augustus left, perhaps, his most profound mark. Near where both the founder of Rome, Romulus, and Julius Caesar had died, he oversaw the draining of a swampland and the construction of marvels of engineering, the traces of which can be seen today in the streets leading north from the Largo Argentina. Entrusted to carry out the work, Augustus's comrade Marcus Agrippa built the Pantheon with statues honoring his emperor, the Saepta Julia with its extraordinary parallel porticoes, and the Diribitorium with the largest roof under a single beam, as well as Rome's first imperial-style public bathhouse. Basins, pools, and fountains were added. To provide the massive amount of fresh water needed for the space and for other development across the river, an aqueduct was constructed. To counter the Tiber's floodwater, the buildings were of brick and concrete and drainage pipes were added. Large spaces, confined within porticoes, were embellished with trees and adorned with statuary and were connected to each other by still other porticoes. Where citizens previously had come to walk quietly through open fields, now they strolled or jostled within a network of marbled colonnades. While still consolidating the reins of power, Octavian had encouraged those allied with him to build within the Campus Martius, and two other entertainment venues were constructed there, an amphitheater and another theater. With voting of lessening significance in the imperial age, the Saepta Julia was turned into another site for shows. In a few short decades the Campus Martius had gone from a spacious war memorial and periodic gathering place to a crowded entertainment district. Now sufficiently developed, the plain was included in Augustus's revampedregiones as Region IX, CircusFlaminius, subdivided into neighborhoods with elected magistrates. Still beyond the pomerium, it was beginning, nevertheless, to have the look and feel of an urban district.
The one part of the Field of Mars that maintained its openness, although now more manicured, was the area between the Aqua Virgo and the mausoleum. Augustus returned to this space late in life and erected symbols of Rome's past and imperial present. Between the area where Romulus ascended to heaven and where Augustus was to be buried, he erected an Egyptian obelisk that cast the sun's shadow on a bronze meridian inlaid in a travertine block pavement. Dedicated to the sun god Sol and proclaiming his defeat of Egypt decades earlier, as well as his recently achieved title as Pontifex Maximus, the horologium was built contemporaneously with an altar celebrating an era of Augustan peace. The Ara Pacis was covered with sculpted images of Rome's legendary founders, Romulus, Remus, and Aeneas or Numa as well as Augustus, Agrippa, and members of the emperor's family. Whether or not the gnomon's shadow pointed to the altar on the emperor's birthday, the horologium, altar, and mausoleum were clearly meant to imbue the northernmost portion of the plain with rich symbols linking the field's mythical past with the imperial present. In its totality, the Augustan Campus Martius must have been to citizens and visitors alike a marbled wonderland that allowed Strabo without hesitation to denigrate the rest of the city as “a mere accessory.”
With the model established by Rome's first emperor, Augustus's successors did not hesitate to expend large sums on refurbishing older structures there and adding to an increasingly crowded landscape. Some of the work was necessitated by devastating firesthat ruined structures in a manner that periodic flooding could not. A few buildings such as the Pantheon were built on a grander scale after their destruction, others such as the Diribitorium were just left open to the sky when its roof collapsed, and still others such as the Amphitheater of Statilius Taurus were never rebuilt. The shrunken remaining space of the Villa Publica that had served as a republican gathering space for so many centuries was enclosed after the fire of 80 C.E. into the Divorum, a temple complex that possibly contained the altar to Mars that had sat alone in the field centuries earlier.
While there was sufficient clear space in the center of the plain in the mid-first century C.E. for the Neronian baths to be constructed but a few hundred meters from those of Agrippa, by the time that they were expanded a century and a half later by AlexanderSeverus, nearby buildings were demolished to make room. The Aqua Virgo that had met most of the freshwater needs of the Campus Martius was now insufficient. A second aqueduct had to be erected to supply Alexander's baths. Room was found for additional temples, and entertainment venues were also wedged into the space with Domitian adding a stadium for Greek games and the Odeum for musical performances and other spectacles.
Reinforcing the themes of imperial divinity and apotheosis that had been established by Augustus, Hadrian and his Antonine successors added a temple to Hadrian's mother-in-law, the Divine Matidia, and a temple to the Divine Hadrian built by AntoninusPius. Two memorial columns were erected. One displayed scenes along the shaft of Marcus Aurelius's battlefield victories. On the base of another, Antoninus Pius and his wife were shown rising heavenward while a personification of the Campus Martius held up the horologium gnomon. Monuments memorializing their ustrina are believed to have been in the same vicinity.
As the Campus Martius became more tightly integrated with the city proper to the south, the significance of the pomerial boundary became blurred. Claudius redrew the sacred lines that pushed the ceremonial limits into the central Campus Martius, and in the late third century C.E., the Aurelian Wall brought the entire Campus Martius within the physical embrace of the city. Apart from the monumental structures that nestled tightly together, remaining room existed in the spaces between colonnades, baths, and temples to be filled by more utilitarian edifices. Apartment buildings contributed to the density and verticality of the Field of Mars. Whatever distinctions relegated the city to “accessory” status at the time of Augustus, by the late third century C.E., the once-open field and the city proper were one and the same, with as many as a million people coursing through the tight arteries connecting the various portions of the urban space. A millennium had passed since the city's mythical founder rose in a cloud from the swampy field, and centuries had elapsed since troops mustered there for battles against northern tribes. Memorials to that storied past still remained and were likely admired by those not otherwise racing to a show, the baths, or their next meal. Over time, however, they too would fall, leaving only a palimpsest for the modern city to trace.
Before another millennium had passed, the Campus Martius of the early common era was barely recognizable, but the standing structures and the detritus of a once great empire left a profound impression on those who wandered through the space. Writing in the twelfth or thirteenth century, a learned visitor to Rome from England, Magister Gregorius, marveled at those edifices in the Field of Mars whose antiquity was clear but whose names were not as certain.2 Gregorius admired statues collected from fallen temples in the area of the Pantheon and arranged in front of the rotunda, later to be recorded in drawings by other visitors to the city, some of whom even took the time to measure the impressive width of the building.3 Yet by this date, few of Rome's monumental imperial edifices remained intact. Looking down at the city from the heights of one of Rome's hills, Gregorius recorded that the grand structures of the ancient world had been replaced by a “forest of [medieval] towers.”4 Another visitor needed no sylvan metaphor to describe the urban disintegration. Now overgrown, parts of the city were “thick woods [with] wild beasts, hares, foxes, deer and even so it is said porcupines breed in the caves.”5 The level topography of the once marshy field that had been so dramatically altered by great marble-faced buildings was transformed further as newer structures were erected on the ruins of the old. In 1581, the great French essayist Michel Montaigne traveled to Rome and noted in his journal that “upon the very wrecks of the ancient buildings, as they fall to ruin, the builders set out casually the foundations of new houses, as if these fragments were great masses of rock, firm and trustworthy. It is evident that many of the old streets lie more than thirty feet below the level of those now in existence.”6
The destruction of the imperial Field of Mars, however, occurred slowly. To any one generation, change was almost imperceptible and certainly did not take place in a linear manner. For instance, in the fourth century C.E., while stones from the Theater ofMarcellus were being taken to repair the Pons Cestius and a glassmaking shop was set up in the portico adjacent to Balbus's theater, an enormous portico, the Porticus Maximae, was built from the Circus Flaminius to the Pons Aelius. Concurrently, a large temple and portico to Bonus Eventus was erected near Agrippa's baths, and the Theater of Pompey, still a site for popular entertainment, was repaired.7 The emperor had moved from Rome to Constantinople, but the show, as it were, went on. When the emperor Constantius II traveled to the former imperial capital in the mid-fourth century C.E., he visited the Theater of Pompey and the Stadium of Domitian and marveled at the Pantheon appearing “like a self-contained district under its high and lovely dome.”8 The year before his arrival, however, the pagan temples that had been financed by republican generals in thanks for battles won were closed. Buildings dedicated to the Christian prince of peace now began to occupy the space. Some temples became the supporting material for early Roman churches. S. Nicola in Carcere, built in the sixth century, sits over the Temple of Juno Sospita in the Forum Holitorium with the ruins of Spes and Janus hard up against it. Rather than being razed, the Pantheon became S. Maria ad Martyres in the early seventh century. In 663 its bronze roof tiles were removed, later to be replaced with lead, an act that Gregorius decried as the result of “excessive avarice and the ‘excessive greed for gold.’”9
Once protected by its walls and its military might, Rome was clearly susceptible to attack after its capital moved. It was burned and sacked twice in the fifth century, first for three days by the Visigoths in 410, and then for fourteen by the Vandals in 455. In 472, the city suffered a five-month siege. What structures invaders did not completely destroy were weakened or leveled by the forces of nature. Three powerful earthquakes racked the city between 408 and 508, and two major floods washed over the low-lying spaces in 398 and 411.10 The fallen marble facing and columns were often just tossed into kilns (calcaria) and burned into lime powder for reuse in mortar for newer buildings. Set up near the Baths of Agrippa, the kilns gave the district its nickname, calcarium, and were used into the Renaissance.11 In some respects the ancient Campus Martius did not simply fall down, it melted away.
By the ninth century new roads had been cut through the ancient porticoes, obscuring the orthogonal lines set during the late republic and early imperial era in the central Campus Martius.12 The massive stone theaters were converted from entertainment venues to strongholds and residences. Balbus's theater became known as the Castrum Aureum or “Golden Castle” and the Theater of Marcellus, which was in ruins by the eighth century, became a fortress in the twelfth century and was then transformed into apalazzo in the sixteenth. The great Theater of Pompey was restored and held performances as late as the sixth century, but it, too, was in ruins by the eighth century and then succumbed to the development needs of one of the wealthy Roman families. In the thirteenth century, the Orsini turned the cavea into a fortress.13
The population of Rome shrank in the early medieval period to just a few thousand residents, perhaps as low as 5,000. While it has been generally assumed that this handful of people was concentrated primarily in the Campus Martius, recent scholarship suggests that the plain was essentially deserted until the tenth century when clerics and nobles moved in, seizing large unoccupied areas for monasteries and palaces.14 A millennium after Augustus, a new generation of powerful men recognized the potential of the Campus Martius for development and erected imposing structures on the plain north of the Capitoline. Although the construction in the Field of Mars during the age of the emperors was dictated in large part by the space's mythical past, the medieval and Renaissance building projects were in spite of it. Over time, the rubble-filled plain developed mounds, or monti, now referenced in several street names and buildings, as the ground level rose above the foundations and walls of ancient structures. The Theater of Marcellus became the “Monte Savello,” and on a rise in the street behind the location of the Circus Flaminius is the Monte dei Cenci.15
Many visitors to Rome over the centuries have despaired over the loss of the antique. Gregorius lamented, “For although all of Rome lies in ruin, nothing intact can be compared to this.…I believe this ruin teaches us clearly that all temporal things will soon pass away, especially as Rome, the epitome of earthly glory, languishes and declines so much every day.”16 Some reached for metaphors to describe, perhaps wistfully, the ruins around them. In 1535, the humanist Alexander Steuco wrote, “Often…wandering through the ruins of the ancient city, I was not able to contain either my tears or sighs, partly commiserating over the miserable destruction of so great a city, partly deploring the instability of human things.…Everything is cadaverous, in ruins, just like the bones of a once beautiful body.”17 Four hundred years later Charles Dickens described the “battered pillars of old Pagan temples, dug up from the ground, and forced, like giant captives, to support the roof of Christian churches.”18 Slowly, over time, the ancient calcium “bones” were absorbed into the surrounding structures. By Dickens's day, the surviving scattered column drums, capitals, and other marble pieces, not otherwise scooped up to fill private collections or grace palazzi, could be seen protruding from stuccoed walls. As the English novelist observed, “It is strange to see, how every fragment, whenever it is possible, has been blended into some modern structure, and made to serve some modern purpose – a wall, a dwelling place, a granary, a stable – some use for which it never was designed, and associated with which it cannot otherwise than lamely assort.”19
Having been on the outskirts of Rome proper for so many centuries, the former Campus Martius today is the centro storico, the historic center. It is now mostly a baroque space punctuated throughout with Renaissance, medieval, and ancient structures. Preoccupation in the early twentieth century with the ancient past at the expense, perhaps, of its medieval successor resulted in the recovery of many ancient monuments that had been covered in part with the Tiber's deposits. Excavations around the Theater ofMarcellus and in the Largo Argentina were conducted under the watchful eye of a latter-day emperor, Benito Mussolini, who also cleared the space around the mausoleum of Augustus to showcase his own imperial style of architecture. After 2,000 years, the Campus Martius still had the power to attract grandiose schemes. But while some have decried the disappearance of the ancient city and occasionally, like Mussolini, have tried to bring it back to the surface, the fact of the matter is that it never totally disappeared. Despite a few “monti,” the field still opens as a wide plain below the surrounding hills, and its buildings preserve a profile not much different from that found at the height of the empire. Many of the ancient arterial routes can still be traced and the outlines of major monuments such as Pompey's theater and Domitian's stadium remain visible. But the real proof can be found in wandering the crowded streets of the centro storico during an early evening passagiata when the modern Romans, walking arm-in-arm, carry on the same conversations that animated their ancestors two millennia ago. The hawkers of street goods and food vendors continue to fill the travel paths. Selius can still be seen racing around looking for his next meal. Martial continues to complain about being dragged off to a passé establishment instead of a trendier one. The ancient Romans never left; they are all there. To those standing in the shadow of the Pantheon observing the birds circling above, lit by the setting sun, it is obvious today as it was to Strabo, the rest of the city is a “mere accessory.”