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.

With the onset of winter in 169 b.c.e., Perseus, the King of Macedonia, was wary that the forces of Rome would attack his poorly defended kingdom. Earlier that year, envoys from Rome had traveled through the Peloponnese and Aetolia south of Macedonia, shoring up the support of allied cities. Now, Perseus expected the worst. Knowing that the Illyrians along the modern Dalmatian coast to his west had been wavering in their support for Macedonia and could provide Rome with a pathway to his kingdom, Perseus decided to take the offensive. Waiting until the winter solstice when the snows protected him from invasion across the western passes from Thessaly, Perseus invaded Illyricum, capturing a Roman garrison. With one success under his belt, Perseus continued to attack and overran eleven other Roman forts. A powerful Roman response was now assured.

With war against the Macedonians clearly on their minds, the Romans chose their two consuls and six praetors for the upcoming year. Lucius Aemilius Paullus was elected consul and directed to lead the forces against Macedonia. Gnaeus Octavius was chosen as a praetor and tasked with conducting Rome's naval operations. In April 168 b.c.e., shortly after the Latin Festival concluded, the fleet departed east. Octavius's warships traveled up the east coast of Greece to Heracleum, Meliboea, and the island of Samothrace. At these locations, Octavius would have seen extraordinary Hellenistic architecture, particularly at Samothrace with its remarkable sanctuary complex composed of altars, a circular theatrical area, banquet rooms, a monumental gate, and a colonnade. Approximately 104 meters long, the Samothrace colonnade was one of the largest in Greece. Two aisles were created by two rows of columns, one down the center of the enclosed space and the other along its eastern edge. The western length and the ends were enclosed. The colonnade sat next to a fountain crowned by the famous Nike of Samothrace, now in the Louvre. Situated on a hill, the marbled colonnade would have afforded Octavius with a panoramic view across the entire complex.

During or just after the reign of Rome's first emperor Augustus (r. 27 b.c.e.–14 c.e.), the Greek geographer Strabo penned his work Geographica and provided a valuable description of many of the peoples and places in the Greco-Roman world. When Strabo reported the “best accredited story of the founding of Rome,” he recounted the tale, “partly fabulous but partly closer to the truth,” of Rhea Silvia, a woman forced by her uncle Amulius to become a Vestal Virgin to assure she would remain childless, thereby preventing the birth of a potential political rival. Notwithstanding her sacred inviolability, Rhea Silvia was impregnated by the god Mars. She gave birth to Romulus and Remus, semidivine twin boys who grew into manhood, defeated Amulius and his sons, and established the foundations for the city of Rome.

Lacking natural defenses and usable arable land, the location for Rome's foundation was suitable “more as a matter of necessity than of choice.” For his part, Strabo forgave the early Romans for not beautifying their city, citing their understandable preoccupation with matters of government and war. The successors to Rome's mythical founders would eventually reduce its vulnerability by building protective circuit walls and defensive gates as early as the fourth century b.c.e. By the reign of Augustus, however, Strabo noted that circumstances had indeed changed. Rome's leaders of the late republic and the first imperial court had not neglected the city's infrastructure; rather they filled Rome with “many beautiful structures.”

If you were on the Capitoline facing north on a summer's day in 717 b.c.e., you would have witnessed, according to Plutarch, a large thundercloud drifting ever lower until it touched the swampy ground in the general area where the Pantheon now stands. That ominous mist was about to envelop and carry off Rome's sacred and mythical founder, Romulus. Livy described the fantastical scene occurring on the Nones of Quintilis (July 7), noting that,

On seeing Romulus's throne empty, the citizens unanimously recognized that their king had transformed into a deity; they quickly declared Romulus to be a god and the son of a god. This story is revealing in several respects: it suggests a popular recollection of the Campus Martius as a place to muster troops; it notes the early topography of the area as marshy; and, by describing Romulus's ascension, it creates the conditions for a sacred space. As discussed later in this chapter, many centuries after this mythical event, Romans were still making an annual pilgrimage to the Caprae Palus on a holiday called the Nonae Capratinae (Nones of the Goat), possibly to celebrate Romulus's apotheosis.

To Vergil, it was the majestic “Father Tiber”; to Statius, the “prince of rivers”; to Dionysius Periegetes, the “most kingly of rivers”; and to Martial, the “sacred Tiber.” Encapsulating these ancient assessments, a recent study describes the Tiber as the “center of traditional stories of the foundation of Rome in which it appeared as a benevolent collaborator.” The great river carried the basket bearing the twins Romulus and Remus as well as the sacred grain of Tarquinius Superbus that formed the Tiber Island. For Romans it was both source and receptacle of divine power. In Vergil's Aeneid, the river's associated god Tiberinus appeared to Aeneas and prophesized the future site of Rome along the river's banks. Sacred springs such as the Cati fons drained into the Tiber (by way of the Petronia Amnis and other rivulets), and Ovid wrote that nymphs and naiads haunted the river's shoreline.

Occasionally, the Tiber overflowed its banks, and while Plutarch wrote that citizens regarded one of its highest floods, which occurred during the brief reign of Otho, as a “baleful sign,” this was not always so. Interpreting the Tiber's floodwaters in 27 b.c.e. as a positive omen, soothsayers prophesized that Augustus would “hold the whole city under his sway.” For much of the year, however, the river remained safely contained within its banks. Pliny the Elder described the Tiber as the “tranquillest purveyor of the produce of the whole globe.” Livy wrote that it carried on its placid surface the “fruit of inland places” and the “seaborne produce from abroad,” and as Juvenal recorded, the river brought the languages and customs of distant countries to the capital. In places the current flowed calmly enough to allow swimming. Cato the Elder taught his son to swim in the Tiber, and soldiers would take a dip following military exercises. Generally praised in the ancient sources, the Tiber nevertheless had its more dangerous side. The Tiber's heavy winter flows not only led to the often destructive flooding of low-lying areas of the city but also likely contributed to the presence in the late summer and fall of “tertian fever,” a malady known today as malaria.

A Second-Century Rivalry

Despite having been elected consul a few days earlier on February 18, 188 b.c.e., Marcus Aemilius Lepidus was very displeased. The day after his selection along with co-consul Gaius Flaminius, six praetors were chosen, and now the Senate would decide to which region of the expanding empire each would be sent. War was brewing with the Ligurians in the northern part of the Italian Peninsula, and the Senate decreed that the two consuls should proceed in that direction to keep the peace. Lepidus objected, arguing to the Senate that “it was improper that both consuls should be shut up in the valleys of the Ligurians while Marcus Fulvius [Nobilior] and Gnaeus Manlius for two years now [as consuls], the one in Europe, the other in Asia, were lording it as if they were the successors to Philip [of Macedon] and Antiochus [the Great].” Lepidus had a particular grudge against Fulvius, who had managed to thwart his efforts to become consul two years earlier. The sole activities of the former consuls, Lepidus claimed, were threatening tribes against whom no war had been declared and enriching themselves by “selling peace for a price.” Either send the newly elected consuls to Europe and Asia to replace Fulvius and Manlius, he pleaded to the Senate, or bring those soldiers home. Unfortunately for Lepidus, the Senate chose the latter course. With their term starting on the New Year on March 1, 187 b.c.e., Aemilius Lepidus and his co-consul Flaminius were ordered north to battle the Ligurians.

Having climbed the slope of the steps of a wooden amphitheater, Corydon, a creation of the poet Titus Calpurnius Siculus, vividly describes taking his seat in the upper level among the poor in their unbleached cloaks and near the benches where women were allowed to view the spectacle below. If the events set out in his eclogue took place in 57 c.e., as many scholars believe, then the poet Calpurnius had likely observed the Campus Martius from the recently completed structure built in less than a year under the orders of Emperor Nero. Employing a veritable forest of wood, including the largest larch tree ever brought to the capital, Calpurnius/Corydon tells us that the amphitheater rose on interwoven beams above the flat plain of the Campus Martius in two curved sections, creating an oval arena on the center floor.

From Corydon's words, we might imagine Calpurnius at the amphitheater surveying the crowd and incidents to include in his work. Before the show grabbed his attention, perhaps he looked out across the Field of Mars and saw in the distance the Capitoline Hill, appearing not much taller than the amphitheater itself. From his high perch atop the theater, the poet would also have seen a remarkable sight. Once a marshy military exercise ground, the plain was now the premier entertainment district within a bustling, urban landscape. Captured in Calpurnius's view from this impressive, albeit temporary entertainment site, would have been the even more extraordinary and permanent stone theaters and amphitheater constructed by great men during the waning days of the republic. These massive edifices significantly influenced the transformation of the topography of the Campus Martius. The Amphitheater of Statilius Taurus was then approaching its ninth decade of hosting gladiatorial and animal exhibitions. Constructed a century before Nero's temporary structure was raised, the curved walls of Rome's first and largest stone theater, the Theater of Pompey, would also have been visible. Indeed, it rose higher than the amphitheater where Calpurnius sat. About half a kilometer southeast of Pompey's theater, another theater sat close to the riverbank, this one built by Augustus to honor his deceased nephew Marcellus.