Arch of Constantine (315): Rome's Last Great Triumphal Arch

The Arch of Constantine is a triple triumphal arch in Rome, standing between the Colosseum and the Palatine Hill. The Roman Senate dedicated it in AD 315 to honour the emperor Constantine’s victory over his rival Maxentius three years earlier. It is the largest surviving Roman triumphal arch and the last great one built in the city, and its mix of reused older sculpture and new reliefs makes it a key monument for understanding how Roman art and power changed at the start of the Christian era.

Background: a victory to celebrate

On 28 October 312 Constantine defeated Maxentius, who had ruled Rome since 306, at the Battle of the Milvian Bridge just north of the city. Maxentius drowned in the Tiber, and Constantine entered Rome the next day as its new master.

The Senate, eager to win favour with the victor, voted him honours. These included the arch, placed on the route followed by triumphal processions as they approached the Forum. It was dedicated in 315, during Constantine’s decennalia, the celebrations of his tenth year in power, when he visited Rome in the summer of that year.

Triumphal arches had long been built in Rome to mark victories, among them the Arch of Titus, celebrating the capture of Jerusalem, and the Arch of Septimius Severus in the Forum. Constantine’s arch followed the triple-bay design of the Severan arch but on a larger scale.

Design and dimensions

The arch is about 21 metres high, 25.9 metres wide and 7.4 metres deep. A large central passage is flanked by two lower side passages. Eight free-standing columns of yellow Numidian marble stand on tall bases on the two main faces, carrying statues above.

On top sits a tall attic storey bearing the dedicatory inscription on both faces. The arch stood close to two other landmarks of imperial Rome: the Colosseum and the Meta Sudans, a monumental fountain whose foundations can still be seen nearby.

Reused sculpture: the spolia

The arch is famous for its spolia, the term used for building materials and decoration taken from older monuments. A large part of its sculpture came from structures honouring three emperors of the second century:

• Trajan (ruled 98–117): Eight statues of captive Dacians, from the region of modern Romania, stand above the columns on the attic. Four panels of the “Great Trajanic Frieze”, showing battle scenes, were set into the central passage and the short ends of the attic.
• Hadrian (ruled 117–138): Eight round reliefs, or tondi, about 2.4 metres across, show hunting scenes and sacrifices to gods such as Apollo, Diana, Hercules and Silvanus.
• Marcus Aurelius (ruled 161–180): Eight rectangular panels on the attic show the emperor at war and in civic ceremonies, probably taken from a monument of the 170s.

In most of these reliefs the head of the original emperor was recut as a portrait of Constantine. In some of the hunting roundels a second figure was given the features of another ruler, often identified as Licinius, Constantine’s co-emperor at the time, or his father Constantius I.

The Constantinian frieze

Newly carved in 312–315 is a narrow frieze running around the arch above the side passages. It tells the story of the campaign of 312 in a series of scenes: Constantine’s army setting out from Milan, the siege of Verona, the battle at the Milvian Bridge with soldiers drowning in the Tiber, and the emperor’s entry into Rome.

On the north side, facing the city, two further scenes show Constantine addressing the people from the speaker’s platform in the Forum and distributing money to citizens. The figures are short and stocky, set in rigid rows, and the emperor is shown frontally at the centre, larger than those around him.

Other Constantinian decoration includes Victories and river gods in the spandrels above the arches, roundels of the Sun and the Moon on the short ends, and reliefs on the column bases showing Victories and captive barbarians.

The inscription

The inscription, repeated on both main faces of the attic, states in Latin that the Senate and the Roman people dedicated the arch to Constantine because, “by the inspiration of the divinity” (instinctu divinitatis) and by the greatness of his mind, he had avenged the state with his army on the tyrant and all his faction at a single stroke.

The phrase about divinity has attracted much attention. It names no particular god, so that traditionalist senators and Christians could each read it as they wished. Some scholars think the words were added or adjusted to suit Constantine’s new religious outlook, but this is uncertain.

Debate over its history and style

For centuries the arch was taken as evidence of artistic decline: the polished second-century reliefs look very different from the squat figures of the Constantinian frieze. The art historian Bernard Berenson published a book in 1954 subtitled “The Decline of Form”. Many scholars now see the newer style instead as a deliberate change towards clear, symbolic images that focus on the emperor, foreshadowing medieval art.

The reasons for the spolia are also debated. Reusing sculpture from Trajan, Hadrian and Marcus Aurelius linked Constantine with emperors remembered as good rulers. It may also reflect a shortage of skilled sculptors and the speed with which the monument was completed.

Excavations in the 1990s led some archaeologists to argue that parts of the structure date from an earlier arch, possibly of Hadrian’s time, which Constantine’s builders remodelled. Others reject this view, and most scholars still regard the arch as essentially a work of 312–315.

Later history

In the Middle Ages the arch was incorporated into the fortifications of the powerful Frangipani family, which helped protect it. Restorations followed from the Renaissance onwards; in the 1730s, under Pope Clement XII, several damaged figures were repaired and missing parts replaced.

The arch inspired later monuments, including the Arc de Triomphe du Carrousel in Paris and Marble Arch in London, both modelled on Roman triple arches. It was cleaned and restored in the late twentieth century, and in September 2024 a lightning strike during a storm damaged part of its attic, which was then repaired.

By the numbers

The figures show how much of the decoration was borrowed. Apart from the narrow frieze, the spandrel figures, the column bases and the roundels of Sun and Moon, most of the sculpture a visitor sees today was carved for earlier emperors, generations before Constantine was born.

Timeline

• 312, 28 October: Constantine defeats Maxentius at the Milvian Bridge.
• 312, 29 October: Constantine enters Rome.
• 312–315: The arch is built and decorated.
• 315, summer: The arch is dedicated during Constantine’s tenth anniversary celebrations.
• Middle Ages: The arch is incorporated into the Frangipani family’s fortress.
• 1730s: Pope Clement XII sponsors restoration.
• 1954: Bernard Berenson’s study of the arch’s style is published.
• 2024, September: Lightning damages part of the attic.

Why it matters

The Arch of Constantine is a monument of transition. It celebrates a victory that began Rome’s turn towards Christianity, yet it speaks the language of traditional Roman triumph. Its reused second-century masterpieces and new Constantinian reliefs show, side by side, how art, power and religion were changing as the ancient world gave way to late antiquity and, eventually, to the age of Constantinople.