What is the Campus Martius?
The Campus Martius, or Field of Mars in English, is a specific region in the ancient city of Rome.
This district comprises a floodplain of about two square kilometers in area and spans from the traditional center of Rome to the banks of the River Tiber.
Since before recorded history, the Campus Martius has had religious and cultural significance for local peoples.
This is likely due to the presence of the Ara Martis, or Altar of Mars, that was there from at least the 8th century BC, but disappeared some time during Rome's Regal Period.
From the earliest days of Roman society, the Campus Martius was the location of religious rituals. The most well-known of these is the ritual Rome's soldiers would perform there before leaving to fight a campaign in foreign lands, but offerings to deities in hopes of a bountiful harvest were common as well.
When the last Roman king, Lucius Tarquinius Superbus, took control of the field, it was portrayed as part of the greater trend of Tarquinius’ tyranny and disregard for the Roman people and their traditions.
After the fall of Tarquinius and the establishment of the Roman Republic, the Campus Martius became owned by the government and held in public trust. Building permanent structures of any kind would be prohibited there for many centuries.
Romulus, Remus & The Founding of Rome
While the true story of Rome’s founding is shrouded behind the veil of history, the myth of the city's founding is well-known.
The twin brothers Romulus and Remus had a legitimate claim to the throne of Alba Longa, but King Amulius ordered them drowned in the River Tiber to protect his own claim. Years later, after the brothers returned and overthrew Amulius, Romulus founded the city of Rome, some time around 753 BC.
Romulus would serve as the city’s first king and establish the idea of the pomerium, an official boundary for the city of Rome that would go on to have profound religious significance for all Romans.
When it came time for Romulus to die, he ventured outside of Rome’s pomerium to a plain on the River Tiber, near the spot where he and his twin brother had been abandoned as infants so many years before.
According to legend, a storm cloud descended onto that plain to lift Romulus up to Olympus, where he became an important god in Rome's local pantheon. The spot where Romulus ascended became a highly important religious site for the early Roman people.
Due to frequent flooding from the Tiber and its location outside of Rome’s pomerium, no buildings were constructed nor agriculture performed in the area. Instead, citizens would gather there for religious ceremonies to hope for good harvests and success in battle.
After the fall of the last Roman king, Lucius Tarquinius Superbus, his lands - including this important floodplain - were put under the control of the new Roman Republic. This was when the field was dedicated to Mars, an important god in Roman society, and named the Campus Martius, or Field of Mars.
The newly empowered Roman senate decreed that the land would be held in public trust and remain undeveloped for continued use in these important religious ceremonies.
Despite this history, many historians believe that the origins of the Campus Martius’ religious significance, and the altar to Mars that was located there, are much older than the city of Rome. It is more likely that early Romans intentionally included a location that already had religious significance into the mythological tale of Rome’s legendary founding.
The Campus Martius During the Roman Republic
During the final years of Rome’s Regal Period and in the first century of the Early Republic, a number of religious temples were built on the Campus Martius. The temples mentioned in the historical record include temples to Diana, Apollo, Juno Regina, and the twins Castor and Pollux.
However, the locations and details of these temples have been completely lost and some historians wonder if some of them ever really existed at all. The ones that did were relatively crude wooden constructions.
In 435 BC, a 300 meter space was cleared on the Campus Martius for the purpose of gathering all of Rome’s citizens every five years for a census. This space, called the Villa Publica, would be used for centuries to come.
In the 3rd century BC, Rome would become embroiled in the Punic Wars, which would project Roman military power outside of the Italian peninsula for the first time. This led to a change for the Campus Martius in two important ways.
First, the presence of fighting men abroad lessened the frequency of military ceremonies there. Second, the wealth flowing into Rome from its conquests against Carthage in the Punic Wars increased the demand and the capacity for bolder building projects in and around Rome, including the Campus Martius.
During the Hellenistic period of Roman history that followed the Punic Wars, the longstanding tradition of avoiding large building projects on the Campus Martius began to erode.
Seven new architecturally-advanced temples built of stone and mortar were erected, including those to Bellona, Fortuna, and Hercules. These temples and other more minor monuments were constructed by generals and politicians who had prayed to these deities before being victorious in major battles.
To supplement these great works and the accompanying increase in activity on the Campus Martius, wooden markets and entertainment venues were also constructed in the area, although they were always meant to be temporary.
As Rome won more conquests and became increasingly militarized, the Campus Martius became a primary training ground for the Republic's legionaries, continuing the ancient military traditions of the floodplain.
Transformation During the Imperial Period
In the latter half of the 1st century BC, a series of tumultuous events, including the rise, fall, and eventual assassination of Julius Caesar, led to Rome’s transformation from a republic to a totalitarian empire. The first true emperor of Rome was Caesar Augustus, an adopted son of Julius Caesar, who ascended to the position in 27 BC.
Augustus made a huge range of reforms to the social, political, and economic systems in Roman society. The Campus Martius was caught up in this change as well when Augustus declared that it would officially become part of the city of Rome, ending the ancient boundaries defined by the city’s pomerium.
Augustus would go on to build massive and impressive engineering projects on the Campus Martius in an effort to show his magnanimity and solidify his prestige as a new ruler. These projects include the Saepta Julia, a building that was originally intended as a public voting place to prevent voter fraud.
As voting decreased severely in importance under Augustus, the building was used for other public uses, including gladiatorial combat. The Baths of Agrippa, the first of Rome’s great public bath houses, was also built on the Campus Martius during this time.
Although it would not be completed until much later, the foundations of the Roman Pantheon were laid down during Augustus’ reign. After the death of Augustus, a great monument called the Ara Pacis, or Altar of Peace in English, was constructed to honor the era of peace that began with his consolidation of power. Even Augustus’ mausoleum was built there. Following all of these huge public works, the Campus Martius was transformed forever.
Subsequent emperors would go on to follow this precedent set by Augustus. Caligula constructed a great temple to the goddess Isis there. Nero built his infamously opulent bath house there. Domitian built a stadium there that would go on to become the Piazza Navona. The area became a bustling nexus of activity of all kinds.
When Rome’s military dominance waned and local barbarian tribes became a threat to the city around 270 AD, the emperors Aurelian and Probus extended the city wall around the Campus Martius, formally making it a part of the city more or less similar to any other.
The Post-Roman Era
A series of disasters, including two sackings by hostile barbarians, destroyed much of the city’s infrastructure in the 5th century AD. As a result, the population greatly diminished, as it did in cities all across Europe.
The Campus Martius became one of the main places that people lived due to their increased reliance on being close to the River Tiber for daily needs. The road that entered the city through the Campus Martius also became the safest and most used route into Rome.
As time wore on and the Vatican became a source of great power and wealth, the area became the most densely populated part of the city, and stayed that way throughout the Middle Ages. As a result, some Popes took steps to improve the condition of the Campus Martius, including Leo X, who restored some of the ancient Roman aqueducts to functional condition in an effort to improve hygiene within the district.
Following the Italian Renaissance, few alterations were done until the modern state of Italy was founded at the end of the 19th century. The Italian government constructed many new apartment buildings in the Campus Martius, as well as earthworks to help prevent flooding from the nearby River Tiber.
