The building and its context
The Basilica of Maxentius was begun by Emperor Maxentius (306–312 AD) and completed by his successor Constantine I after the Battle of the Milvian Bridge (312 AD). It stood along the north side of the Via Sacra, in the eastern area of the Roman Forum, between the Temple of Romulus and the Arch of Titus.
In the Roman world, a basilica was not a religious building but a large multi-functional civic hall — housing courts, commercial activities and imperial receptions. The Basilica of Maxentius was the largest basilica ever built in Rome: with a plan of approximately 80 × 100 metres, it far exceeded any previous example.
Structure and construction technique
The basilica was divided into three aisles:
The central nave (three bays of approximately 25 × 80 metres) was covered by groin vaults — the intersection at ninety degrees of two barrel vaults — reaching 35 metres in height. This height was exceptional in Roman architecture and remained unsurpassed for many centuries.
The side aisles (three bays per side) were lower, with barrel vaults oriented transversally to the central nave. Each lateral niche measured approximately 20 × 24 metres.
The construction technique was revolutionary: the vaults were in opus cementicium — Roman concrete — rather than stone. Roman concrete was composed of lime, pozzolana (volcanic ash) and aggregates. This mixture, once hardened, was more resistant than ordinary stone under compression and allowed enormous spans to be covered without permanent timber centering.
The eight large columns of Proconnesian marble that supported the entablature of the central nave were monolithic and 14.5 metres tall. The single surviving column was transported in 1613 to Piazza Santa Maria Maggiore, where it stands today.
Maxentius and Constantine: two histories in one building
Maxentius began the basilica as part of a grandiose Forum redevelopment programme. His design featured a monumental entrance on the southern side (Via Sacra) and an apse on the western end.
After Maxentius's defeat at the Battle of the Milvian Bridge (28 October 312 AD) and his death, Constantine took over the unfinished basilica and completed it according to a partially modified design. He added a monumental entrance on the eastern side (facing the Colosseum) and a new apse on the northern side, in which he placed a colossal statue of himself.
The two different entrances — south (Maxentius) and east (Constantine) — created a building with two superimposed axes of orientation, still visible today in the foundations.
The Colossus of Constantine
In 1487, fragments of a colossal statue of Constantine were discovered in the western niche of the basilica — one of the most sensational finds of Renaissance archaeology. The surviving fragments include:
- The head (height 2.6 m)
- The hands (larger than an adult human)
- The feet and calves
- Some parts of the brick torso
The original statue was composed of two materials: the flesh parts (head, arms, legs) were in white marble; the torso and drapery were probably in brick clad with bronze sheet or wood. The total height was approximately 12–13 metres.
The statue depicted a seated, frontally posed Constantine, in the typical iconography of the emperor in his divine aspect. The fragments are today preserved in the courtyard of the Capitoline Museum, where they can be seen.
Influence on European architecture
The Basilica of Maxentius had an extraordinary impact on post-classical European architecture.
Michelangelo studied it intensively when designing the new St Peter's Basilica (from 1546). The distribution of the vaulted bays of the Basilica of Maxentius provided the direct model for the plan of St Peter's crossing. Michelangelo explicitly stated he would replicate the same system "bigger, taller and higher" — and the dome of St Peter reflects this ambition.
The concrete groin vault construction system influenced:
- The great railway stations of the 19th century (Gare du Nord in Paris, St Pancras in London)
- The exhibition pavilions of the 19th century
- Neoclassical churches throughout Europe
The structural principle of the Basilica of Maxentius — enormous covered space with minimal wall supports — is one of the red threads of Western architecture from the 5th to the 20th century.
The three surviving arcades
Of the original three side bays of the north aisle, the three surviving arcades are probably why the basilica is still relatively recognisable. The central nave has been completely lost — partial collapse in 847 AD during an earthquake, progressive collapse in subsequent centuries.
The surviving arcades are approximately 20 metres high and 16 metres wide each. The structure visible today is essentially the external north wall with the vaulted niches of the north side of the lateral aisle.
The earthquake of 847 AD is considered primarily responsible for the collapse of the central nave vaults — a single seismic event that destroyed the most architecturally impressive element of the building.
How to visit it today
The Basilica of Maxentius is located within the Roman Forum area, accessible with the combined ticket.
- The three north arcades are visible from outside along the Via Sacra and are fully appreciable from this viewpoint
- The west apse (where the Colossus of Constantine was found) is partially preserved
- A digital reconstruction of the basilica is displayed on information panels at the site
- The surviving column stands in Piazza Santa Maria Maggiore (approximately 2 km north of the Forum)
To contextualise the structure: position yourself in front of the arcades and remember that these represent only the side aisles — the central nave was almost twice as high.
Visiting with a private driver
The Basilica of Maxentius is in the Roman Forum, included in the combined Colosseum–Forum–Palatine ticket.
Visit the Basilica of Maxentius and the Roman Forum with a private driver: reach the heart of Roman imperial architecture. Service from €49. → Book your driver at myromedriver.com
Frequently asked questions
Is the Basilica of Maxentius a church? No. In the Roman world, "basilica" referred to a large civic hall (courts, commerce, receptions). It was not a place of worship.
What remains today of the Basilica of Maxentius? The three arcades of the north side (side aisle), parts of the west apse and the remains of the central nave foundations. The central nave has completely collapsed.
Where is the colossal statue of Constantine? The fragments (head, hands, feet) are in the courtyard of the Palazzo dei Conservatori at the Capitoline Museums.
Why was Michelangelo interested in the Basilica of Maxentius? Michelangelo studied it as the model for the groin vaults of St Peter's in the Vatican. The structural system was revolutionary and remained the reference for large European roof structures for centuries.
When did the main collapse of the basilica occur? The earthquake of 847 AD is considered responsible for the collapse of the central nave vaults.
Article no. 45 — TIER S — MON-03 Roman Forum + Palatine Type: HISTORY Words: ~2,400