Milan, Cologne, Istanbul - Surprising Seats of the Roman Empire

Ask the man on the street where the capital city of the Roman empire was and in almost all cases you will get one answer: Rome. Italy's capital is generally accepted as being the Roman empire's seat of power, and indeed it was for most of the empire's history and certainly during the republic. But in the middle of the third century AD, the empire was on the brink of disintegration as two break-away territories threatened to destabilise the status quo. It took 14 years to dominate the Gallic empire, and a little less to defeat Queen Zenobia of Palmyra, but it was clear that the empire's nether provinces needed close attention.

While Rome had gained power through its advantageous position and its ability to dominate other coastal areas in the western half of the Mediterranean, the empire's expansion meant that the capital was increasingly distant from its northern and eastern borders. It was the emperor Diocletian in 293 AD who saw the need to bring the empire's capital nearer to the problematic areas north of the Danube and around the Rhine. He did this by introducing a new system of governance: the Tetrarchy. Diocletian appointed Maximian as his co-emperor for the western half of the empire, while Diocletian himself continued to rule in the east from Nicomedia. Each augustus had a 'deputy', or caesar, who was subordinate to him. The western emperor's administrative base was now Mediolanum, present-day Milan.

Mediolanum

Mediolanum was declared the capital of the western Roman empire in 293 AD and it became the base of Maximian, co-emperor to Diocletian. Mediolanum provided easier access to the provinces of Hispania, Gaul and Britannia, as well as the north-eastern borders.  Its most instrumental political moment came in 313 AD when Constantine signed a guarantee of religious tolerance, which was intended to mark the end of Christian persecutions. This became known as the Edict of Milan.

When the city came under threat from the Visigoths in 402, Honorius moved his residence from Medioanum to Ravenna. Later that century the city was invaded by the Huns and it was eventually sacked by the Ostrogoths in 539 AD.

Ravenna

Even though Ravenna's peak as capital of the western Roman empire came late in the empire's lifetime it had nevertheless always been a town of some importance to the Romans. Previously a peripheral settlement on a water-logged marsh, in 89 BC it became part of the republic and it was then a military resting post for Julius Caesar before his troops historically crossed the Rubicon river, effectively declaring war on the Roman republic in 49 BC. Ravenna grew under the Romans and became the location of Augustus's military harbour, Classis, which purportedly had the capacity for 250 ships and 10,000 sailors and was the biggest such port in the eastern Mediterranean.

With the establishment of Classis, the urban centre of Ravenna began to take shape and town houses and public buildings shot up. During the reign of Trajan (98-117 AD), the first aqueduct was built at Ravenna, carrying water for 70km into the city. The town and port were fortified by city walls, which, along with the surrounding marshland, provided effective protection for Ravenna. It was mainly for this reason that Honorius moved his base there at the beginning of the fifth century.

One of the most interesting Roman remains in Ravenna is the mausoleum of Honorius's sister, Galla Placidia. This dates from around 450 AD with fine examples of Roman mosaics. Mosaics are something that the city is certainly not short of – other examples include those at the via D'Azeglio, an archaeological area where a Roman-era palace has been found with 14 rooms paved with colourful mosaics. The oldest surviving building in Ravenna is the Neonian baptistry, built at the end of the fourth or beginning of the fifth century – this is also duly decorated with mosaics. This can be entered from the church of Saint Euphemia. Many of the Roman structures at Ravenna are now Unesco World Heritage sites.

Colonia Agrippina

With the empire's expansion, there was also a need for administrative centres outside the Italian peninsular. Colonia Agrippina first sprang up as the Roman provincial centre of Germania Inferior but by 260 AD it became the first capital of the Gallic empire, right up until 271 AD when the capital was moved to Trier.

The origins of Colonia Agrippina – modern-day Cologne in Germany – go back to a Germanic tribe called the Ubii, who settled there in around 39 BC in agreement with Roman forces, who also had a military base there. In 50 AD it was given city status at the request of one of its most infamous children, Agrippina the Younger. The wife of Claudius and mother of Nero, this ambitious Julio-Claudian woman went on to achieve notoriety as the possible murderess of her husband, only to be murdered by her own son a few years later. Nevertheless, the city was named after the imperial couple as Colonia Claudia Ara Agrippinensium, later shortened to Colonia Agrippina.

Today some of the Roman remains in Cologne include the Roman Tower, part of the city fortifications from the first century AD, as well as the Weidener Grabkammer, a family mausoleum with an elaborately carved interior and sarcophagus dating from the second century AD. One of Cologne's bridges dates from 310 AD, during the reign of Constantine I, under whom much of Trier and almost all of Constantinople were built. In 2007 a first-century Roman boat was discovered in Cologne's wharf area. After the re-absorption of the Gallic empire into the Roman empire, Colonia Agrippina remained a provincial capital until it was occupied by Frankish forces in 459 AD. Today the Romano-Germanic museum in Cologne displays much of the city's Roman heritage.

Augusta Treverorum

Apart from some traces of neolithic habitation in the countryside surrounding Trier in present-day Germany, there was very little there until the arrival of the Romans. Having defeated the Celtic Treveri tribe some years previously, they then went on to build Trier in 16 BC and named it Augusta Treverorum in acknowledgement of the Celtic land they had conquered. Augustus instated the town as capital of the province of Belgica and it began to thrive.

It wasn't until the Roman empire's crisis of the third century that Trier came into its own: it became the capital of the Gallic empire from 271 to 275 AD. It was the seat of power for the Gallic emperor Tetricus I until he succumbed to Aurelian and the Gallic empire was reunited with the Roman empire. Despite its brief years of glory as centre of its own empire, Augusta Treverorum was sacked in 275 AD by the Alamanni tribe and much of it was destroyed.

However, the best years of the Roman town were yet to come – it was rebuilt following the sack of the Alamanni and 20 years later it became a residence for the emperor of the western Roman empire. When Constantine I came to power in 306, he invested in building in Augusta Treverorum. As well as fortifying the city walls, Constantine started to build a palace in the north east of the city, including a big audience hall, known today as Constantine's Basilica, and imperial bathing houses. Constantine's building projects at Trier were something of a dry-run for his reconstruction of Byzantium 20 years later.

Many of the monuments that can still be seen today date from Constantine's rule, for example he built public baths that were almost as big as the public baths of Caracalla in Rome at that time. They were 200m long by 100m across and had a capacity of several thousand baths. Other structures in Trier pre-date Constantine, such as the Porta Nigra, originally a gate in the old city walls. The Roman wall was built in around 180 AD but this particular part of it later became the residence of a hermit monk and the medieval building constructed over the gate became the two-layered church of St Simeon. Trier also has an amphitheatre dating from the first century AD. This is where Constantine I fed two Frankish kings, Ascaric and Merogaisus, to wild animals after he defeated their tribes in 307 AD.

Nicomedia

Now known as İzmit in Turkey, Nicomedia's origins date back to the eighth century BC when it was known as Olbia or Astacus. Nicomedes I rebuilt the city in the third century BC and it became the provincial capital of Bithynia during the Roman empire. When Diocletian introduced the Tetrarchy system of rule in 293 AD, he designated Nicomedia as the capital of the eastern Roman empire and it was the main residence of Licinius and then of Constantine I until his new capital Nova Roma was built in 330 AD. A double-catastrophe of an earthquake and a fire in 358 AD destroyed Nicomedia and although it was rebuilt, it never regained its former glory, even though it remained an important trade and military town in the Byzantine empire.

Constantinople

Namesake of its founder Constantine I, this new capital of the eastern Roman empire was at first known as Nova Roma, and was very much built with the empire's old capital in mind. Monuments were built on a scale to rival the huge basilicas and temples of the Roman Forum and many are now listed as Unesco World Heritage sites. Constantine's Great Palace, for example, is currently still being excavated and was built as a complex of pavilions covering almost two hectares of land. One of modern-day Istanbul's tourist attractions is a fourth century Roman monument made in imitation of one from the forum: the Milyonbar, which was meant to act as a distance marker for other cities to quote distance to Constantinople. A stone with exactly the same function is also found in the Roman Forum.

Constantinople's other Roman monuments include the hippodrome, the Column of Constantine and the Egyptian obelisk in Sultanahmet Square, which was placed there after the reign of Constantine I.

Despite the fact that Constantine I obviously preferred his new personalised capital, Rome retained its importance in the west by being the seat of key political figures who were influential in the empire's decision-making. However, the advent of these new capitals and administrative centres meant that Rome's star was slowly waning by the end of the third century AD.

Photos by Blai Server, Ilias Katsouras and Julian Kaesler.

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About The Author

Bija Knowles (follow me: e-mail or )

Last three pieces by this author:

300 Looted Antiquities Displayed in the Colosseum | Hoard of 52,500 Roman Coins Discovered Near Frome by Metal Detectorist | Roman Villa Discovered Near Tewkesbury

Bija Knowles is a freelance journalist based outside Rome, Italy. She graduated in Italian and English Literature from the University of Birmingham, UK, and her main areas of interest are art, travel and history in Italy.