According to
Rome's foundation myth, prior to the founding of the city,
Rhea Silvia had her twin sons,
Romulus and
Remus, taken by the King of Alba Longa. The boys were later discarded in the swelling Tiber River, which would later run along the Campus' western boundary. Washing ashore further downriver, the brothers would return decades later to found a new city. Romulus, who became Rome's sole king (after killing his brother Remus), ruled for many years until sometime in the seventh century B.C. As he came to the end of his life, a storm cloud descended upon the center of the open field outside the city's
pomerium in order to lift the elderly king to the afterlife. This land, "between the city and the Tiber", became the property of Rome's last Etruscan king,
Tarquinius Superbus. After his defeat and exile, the plain was dedicated to the god
Mars. Roman men assembled every spring before heading off to fight the hostile tribes that surrounded Rome, and citizens gathered for important religious festivals. With the exception of a small altar to Mars near the center of the field, no visible changes were made to the field until the fifth century B.C. With the advent of the
Punic Wars in the mid-third century B.C., Roman military expansion moved out of the Italian peninsula, resulting in the reduction of seasonal musters on the field. The number of foreign wars, however, greatly increased the amount of wealth flowing into Rome. Generals who had sworn to various deities to build temples in their honor if victorious used the vast amounts of wealth to fund these construction projects. Besides temples and wooden markets, entertainment venues were built as well, though they were to be temporary. Starting in the time of
Sulla, building lots were sold or granted to influential Romans, and
insulae (apartment blocks) and villas encroached on the common land. It later became the place for
comitia centuriata, civic meetings with weapons, and for the city's militia. In 55 BC,
Pompey constructed a permanent theater, the
Theatrum Pompeium, the first stone theater in Rome. When the
Curia Hostilia burned down in 52 BC, the theater was sometimes used as a meeting place for the
Senate. The area was also used as the assembling ground for elections.
Julius Caesar planned for the
Saepta (enclosures used for elections) to be placed there; they were later completed by his heir
Augustus (Octavian). In 33 BC, Octavian dedicated the
Porticus Octaviae, built from spoils of the
Roman-Dalmatian War. During the Augustan period of the early Roman Empire, the area became officially part of the city: Rome was split into 14 regions, and the Campus Martius was divided into the VII Via Lata on the east and the IX Circus Flaminius nearer to the river. The Campus Martius also held the
Ara Pacis (Altar of Peace), built by the Senate to mark the establishment of peace by Augustus. It was intended to symbolize the successful completion of Augustus' efforts to stabilize the Empire.
Marcus Agrippa had the original swampy ground made into a pool and baths in a setting of parkland and temples, the
Laconicum Sudatorium or
Baths of Agrippa. Also, he built the
Porticus Argonautarum and the
Pantheon, which was later rebuilt by
Hadrian as it still stands today. In 19 BC, he also completed the
Aqua Virgo, to supply water to these new baths and fountains. In the non-populated northern area was the huge
Mausoleum of Augustus. Other buildings that were made were the
Theatre of Marcellus, the
Temple for Isis (from around the time of Caligula), the baths and bridge by Nero, and Pompey's theatre, where Julius Caesar was murdered by Marcus Brutus and his allies. After the
great fire of 64 A.D. Domitian rebuilt the burnt monuments plus a stadium (eventually to become today's
Piazza Navona) and an
Odeion (a small performance hall). In 119 A.D, reinforcing the themes of imperial divinity and apotheosis established by Augustus, Hadrian and the succeeding Antonines added a temple to Hadrian's mother-in-law, the Divine Matidia, and a temple to the Divine Hadrian himself built by
Antoninus Pius. As was the case with the first two Flavian and Antonine emperors, the Severans did not commit many resources to construction projects in an already crowded Campus Martius. Their interests lay elsewhere in repairs and commissioning new structures in other regions of the capital. The Campus did not see another major architectural change until the reign of
Aurelian. The citizens of Rome took great pride in knowing that Rome required no fortifications because of the stability brought by the
Pax Romana under the protection of the Roman Army. In 270 A.D., however, barbarian tribes flooded across the Germanic frontier and reached northern Italy as the
Roman army struggled to stop them. To alleviate the city's vulnerability, the emperor ordered the construction of a 19-kilometer-long, 6 to 8-meter-high brick wall, fortified with defensive turrets, named the
Aurelian Walls. Aurelian did not live to see his work completed under his successor
Probus, in 276 A.D. With the completion of the walls, the Campus Martius was finally incorporated into the rest of the city. By the mid-fourth century, when emperor
Constantius II visited Rome, now the former capital, many of the pagan temples were closed. Buildings dedicated to Christianity began to occupy their spaces. Some were reduced to supporting material, some were razed, and some were given new roles, such as the Pantheon. In 663 A.D. its bronze roof tiles were removed and replaced with lead, an act that
Gregorius said was the result of "excessive avarice and the 'excessive greed for gold.'" In the fifth century, Rome was burned and sacked twice: by the
Visigoths in 410 A.D. and by the
Vandals in 455 A.D. Three earthquakes racked the city between 408 and 508 A.D, and two floods washed over low-lying spaces in 398 and 411 A.D. Many marble facings and columns were tossed into kilns to be burned into lime powder for reuse. Writing in the twelfth or thirteenth century,
Magister Gregorius, marveled at those edifices in the Field of Mars whose antiquity was clear but whose names were not as certain. Looking down from the heights of one of Rome's hills, he recorded that the great structures had been replaced by a "forest of [medieval] towers". In 1581, French essayist Michel de Montaigne traveled to Rome and noted 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." ==Geography==