“Every time I describe a city I am saying something about Venice,” Marco Polo says to Kublai Khan in Invisible Cities (1972), Italo Calvino’s reimagining of the Description of the World compiled by Polo and a Pisan storyteller he met in a Genoese prison in 1298. The original introduced Europeans to a world far to their east by leading them on a series of itineraries through the cities, lands, and islands that Polo claims to have encountered during the seventeen years he spent in service to the Great Khan of the Mongols, who was also by then emperor of China.

Calvino transforms this meandering travel guide into a tightly structured set of fifty-five prose poems, in which Polo reports to Kublai of imaginary and often impossible cities: one in which only the plumbing has been installed where houses should be, another divided between a fun fair and a district with “the bank, the factories, the palaces, the slaughterhouse” that packs up and leaves town for part of every year. These tales are organized into eleven different themes—cities and desire, cities and exchange, thin cities, continuous cities—interleaved according to a strict mathematical pattern and interspersed with conversations between Polo and the khan. Kublai wants most of all to hear about Venice, but Polo resists direct description of his hometown: “Memory’s images, once they are fixed in words, are erased.”

It’s hard to imagine that invisible cities could tell us anything about Venice, the most visible city of all. Close your eyes and you can see it, whether you’ve been there or not. And what you see is what I see, and it is what Canaletto saw in the eighteenth century when he painted the Grand Canal. Venice looks the same and it stays the same: the central islands have no ancient backstory before traders established a commercial city-state there in the early Middle Ages, and when Napoleon abolished the Venetian Republic in 1797 it had little effect on the view. Now the sea sometimes covers the streets, but even under water we’d recognize Venice—and so would Marco Polo, and probably Kublai Khan as well.

Compare Venice to an older city, seventy miles south down the Adriatic coast. If you close your eyes and think of Ravenna, what do you see? Most likely, if you’ve never been there, nothing at all. The name sounds promising, seductive even, and you think of mosaics, but they hover out of sight. Even if you’ve visited, you’ll see it differently from others who have been there. One friend describes the startling juxtaposition of ordinary city streets and ancient interiors; another remembers immense churches set apart, as well as a very long beach; and a third recalls the pizza, though it turns out that he was nine at the time. The mosaics themselves change too, with the passage of the sun: you never see the same one twice.

It is one of the many joys of Judith Herrin’s Ravenna that the form of the book captures this sense of fragmentation, in thirty-seven chapters broken down into brief sections. As Herrin traces the city’s glory days from 402 CE, when it became the capital of the Western Roman Empire, to 801, when Charlemagne was hauling off its treasures, different Ravennas crowd up against one another: barbarian cities, holy cities, women’s cities, cities ruled by Romans, Huns, Goths, Greeks, and bishops. Armenian eunuchs come into the story too, aggressive Persians, and a plague in the sixth century CE “carried by fleas clinging to rats that had travelled on ships from the Far East, bringing a deadly poison to all human life,” but the focus is firmly on the Roman world, and for the most part on Ravenna itself, linking the old Roman West with an empire now headquartered at Constantinople.

Ravenna was built on sandbanks and wooden piles in a river estuary in the second century BCE. Julius Caesar supplied it with a naval harbor three miles to the south at Classis (which means “fleet”). Over the following centuries it became a prosperous Roman trading post, crisscrossed by canals and bridges, and connecting the cities of the Po Valley with the riches of the eastern Mediterranean. But it was only as the Roman Empire fragmented that this little town came into its own.

The emperors had long since abandoned Rome itself. In the late third century Diocletian divided the Roman provinces between corulers in the East and West, the better to focus on threats from outside the empire, and he established new capitals nearer the borders at Nikomedia (in what is now Turkey) and Milan. In 330 Constantine moved the eastern capital to Byzantium on the Bosphorus and renamed it Constantinople, while a Gothic siege in 401 highlighted the weakness of Milan’s long walls. The following year the western emperor Honorius moved his administration down the river to Ravenna, an easily defended site set among marshes and lakes and surrounded by two branches of the Po that formed an effective moat.


Signs of Ravenna’s new importance survive in the mosaics that quickly became its trademark. Some of the earliest examples were commissioned by Honorius’s younger half-sister Galla Placidia, whose remarkable life embodies the turmoil of the era. Born in Constantinople, Placidia was taken hostage in Rome by Alaric’s Goths in 409, when she was in her teens, and she married their new king, Athaulf, in Gaul in 414. After he was assassinated and their baby son died, she was traded back to Ravenna in exchange for grain. She then married one of Honorius’s generals and bore him two children. After his death in 421, however, and amid rumors of an overly intimate relationship with Honorius himself, she was sent back to Constantinople, where her nephew Theodosius was emperor of the East. It was a brief visit: Honorius died without issue in 423, and Placidia returned to Ravenna with her son Valentinian, emperor of the West at six years old.

On the family’s return to Ravenna, Herrin tells us, “Empress Galla Placidia was now determined to exercise her authority within the West,” writing and enforcing laws, engaging in diplomacy “and all the other tasks normally undertaken by emperors.” In truth there is little evidence for the extent of Placidia’s power, and the obstacles to her authority would have been considerable. Theodosius had prudently provided administrators from Constantinople, two “masters of soldiers” dealt with military affairs, and the child-emperor had a council of regents that did not include his mother. “Yet the empress mother maintained a marked influence,” Herrin suggests, surely correctly, even if the assertion a page later that “the empress ruled in the name of her son” is more speculative.

What is not in doubt is Placidia’s contribution to the architectural legacy of Ravenna or her rethinking of the purpose of sacred art. Her best-known building is the one now erroneously called her mausoleum; in fact it is a chapel of a larger church long gone. Its fame rests on the extraordinary mosaic decoration that covers the interior, from a starry sky picked out in gold against the deep blue of the dome, to baskets of impossibly tall flowers and fruit extending up under the arches, to a bucolic scene of Christ the Good Shepherd tending some surprisingly skeptical sheep.

More politically interesting is the church Placidia dedicated to Saint John the Evangelist in thanksgiving for her family’s salvation from a storm at sea as they returned to Ravenna. Her mosaics were replaced in the sixteenth century, and the church was bombed in 1944 by the Allies, but antiquarian accounts allow a confident reconstruction of the political portraits Placidia introduced into Christian space for the first time: Honorius and Theodosius in the apse; twelve of Placidia’s ancestors and relatives, including a number of Roman emperors, in roundels on the arch; and above them Placidia herself and her children on their alarming voyage. It is a work of maternal devotion that supports young Valentinian’s claim to his imperial throne by laying out his dynastic connection to multiple Roman emperors on the maternal side, including his predecessor in the West and his colleague in Constantinople.

Herrin is less impressed with Placidia’s parenting, blaming her “inadequacy as a mother” for her adult children’s mistakes, including her daughter Honoria’s ill-judged marriage proposal to Attila the Hun. Herrin also disapproves of Valentinian’s “disastrous decision” in 450 to move the imperial court back to Rome, which she blames for the fall of his dynasty and the collapse shortly thereafter of the Western Empire. Yet by the time Valentinian arrived in Rome the writing was on the wall: Iberia, Gaul, Britain, and North Africa were all under barbarian control, and the Eastern Roman Empire had long been recognized as the one that mattered.

And it lasted: despite a widespread modern differentiation between the Roman Empire proper and Byzantium, its Greek-speaking successor in the east, no such distinction existed in antiquity. Roman emperors continued to rule a Roman Empire of Roman citizens without interruption, however much its borders shifted and sometimes shrank, until the Ottomans took Constantinople in 1453. Even the Western Empire held out in a way until the eighth century: the Germanic commanders who took charge in the fifth century ruled without exception in the name of Rome, which is to say Constantinople.

The first of them was Odoacer, a Hun on his father’s side and a Scirian on his mother’s. He deposed the final western emperor in 476 and made his eastern colleague Zeno an offer he couldn’t refuse: that Odoacer would rule Italy as king under Zeno’s nominal authority. There was no need, Odoacer’s envoys argued, for more than one Roman emperor. Stability returned to Italy and security to Ravenna, where Odoacer ruled from Valentinian’s old palace. In 493 he was deposed by Theoderic, an eastern or Ostro-Goth who had grown up a hostage of the Roman court at Constantinople and had served as a Roman consul. Theoderic took Italy with the consent of the Roman emperor, as well as the practical support of the western or Visi-Goths who already ruled much of Iberia and Gaul, and he became Ravenna’s greatest ruler.


Barbarian Ravenna had two faces. Theoderic wore the purple Persian cloak that Diocletian had adopted as the Roman imperial costume two hundred years before, but he replaced Roman offices and institutions with Gothic ones where they worked better for him. Goths ran his palace, while eunuchs guarded the private quarters, as in Roman Constantinople. Theoderic also maintained a clear division among his subjects between the Gothic soldiers, who were permitted to carry arms, and the Roman taxpayers, who paid for them. And all the while the local town council continued doggedly to register land sales and appoint the nightwatchmen.

A detail of mosaic flooring depicting soldiers in the Fourth Crusade; from the Church of Saint John the Evangelist, Ravenna

DEA/A. Dagli Orti/De Agostini/Getty Images

A detail of mosaic flooring depicting soldiers in the Fourth Crusade; from the Church of Saint John the Evangelist, Ravenna, thirteenth century

Ravenna was a holy city under Theoderic, too, and, in the eyes of many, a heretical one. The missionaries who had converted the Goths to Christianity were followers of a fourth-century Alexandrian priest called Arius who took the superficially plausible view that the Son of God must have been born after his Father and could not therefore consist of exactly the same substance. The Catholic orthodoxy established at the Council of Nicaea in 325 maintained instead that God the Father, the Son, and the Holy Ghost were all made up of the same substance with the same origin. Each position smacked to its opponents of polytheism, an ever-present potential embarrassment for Christians with their unusual triple deity.

The Arian leanings of Theoderic’s Ravenna appear in a baptistery built during his reign where a mosaic of Christ’s baptism depicts him as an unbearded youth, unlike the mature, beatific figure found in the older baptistery built by Nicene Catholics. There is evidence of compromise as well: in the scenes from Christ’s life depicted in Theoderic’s new palace church, he is permitted to grow a beard by the time of the Last Supper. At the same time, twin mosaic “portraits” of Ravenna and Classis on either side of the nave pay homage to the city’s Roman tradition of sacro-political art. The former was dominated by the throne room of the royal palace, where Theoderic sat surrounded by his courtiers; in the latter his court stood in front of the harbor’s magnificent wall.

Unlike Rome, where heretical books were burned, or Vandal Africa, where Nicene bishops were exiled or sentenced to hard labor, Theoderic’s Ravenna was also distinguished by relatively civil cooperation between clerics of different creeds. As Herrin points out, tolerance toward the Nicene majority was only sensible since Arian Goths made up perhaps 14 percent of Theoderic’s subjects, but the king was not afraid of confrontation in defense of other groups: when the Jewish synagogues in Ravenna were burned down by locals, Theoderic required the Nicene bishop and the town council to rebuild them.

The city’s mixed population helped make Theoderic’s Ravenna a great center of translation and learning. Herrin describes how the court attracted Jewish doctors and Gothic geographers, and how the king supported Roman scholars like Boethius, who translated a few precious works by Aristotle into Latin before knowledge of the Greek language more or less disappeared in the West and Greek scholarship became a subfield of Arabic science. Theoderic’s daughter Amalasuintha was trilingual in Latin, Greek, and Gothic, well versed in classical literature, and something of a legal scholar as well.

When Theoderic died in 526 he was buried in a giant Roman bathtub made of purple marble in a mausoleum adorned with imitation Germanic metalwork just outside the city walls. His death left a power vacuum at a moment when an ambitious new emperor was making plans to restore direct Roman rule to the West. Justinian’s brilliant general Belisarius easily recovered North Africa from the Vandals in 533, but the reconquest of Italy proved more difficult, not least because Jews sided with the Goths, who had protected them. Ravenna was nonetheless in Roman hands by 540, along with Rome itself, and by 554 most of Italy. Justinian installed a governor at Ravenna to ensure the safe conduct of taxes back to Constantinople.

One way to measure the changes would be through the archaeological traces of shifting trade patterns: Ostrogothic Ravenna had found strong commercial partners overseas in Vandal Africa; now most of the city’s foreign imports came from the eastern Mediterranean. Herrin is understandably more interested in changing ideas.1 The octagonal church of San Vitale was originally commissioned by an Arian bishop under Theoderic, but by the time it was completed in 547 the altar was flanked by two large mosaic portraits of Justinian and his formidable wife, Theodora, an actress two decades his junior, both dressed sumptuously in Persian-style robes and surrounded by soldiers and courtiers.2 This was a concession to established local tradition: there are no such portraits of the ruling family in the churches of Constantinople. There were also concessions to local pride: Justinian follows behind Ravenna’s clergy. The mosaics nonetheless underline Ravenna’s diminished status: an imperial city again, but not an equal partner.

Portraits of the city’s new overlords were not enough: soon the period of Gothic rule was literally obliterated, as Justinian ordered the transfer of all Arian properties to the Catholic community. Theoderic’s palace church was rededicated to the anti-Arian Saint Martin, and a new Nicene bishop removed Theoderic and his courtiers from the portraits of Ravenna and Classis. He replaced them in the former with empty, curtained spaces, and in the latter with a plain brick wall; the only remaining signs of the earlier era were a few stray hands and feet that overlapped with columns or the floor.

Roman power over much of Italy didn’t last long. In 568 a new group of long-bearded barbarians, the Lombards (langobardi), crossed the Alps, led by Alboin, a charismatic king who had made one of his enemy’s skulls into a pearl-encrusted drinking cup. They met little resistance from Constantinople in occupying much of the country: in the East the Persians were on the attack again and a new emperor, Justin II, was going mad. The Lombards left him Rome, Ravenna, a road corridor over the Apennines between them, and a few strategic ports.

This odd patchwork of territories clung on in awkward symbiosis with the Lombards for almost two centuries, but for Ravenna it was a difficult phase. Within the city the bishop, who was chosen by the local clergy and answered in theory to the pope in Rome, was often at loggerheads with the Roman governor. Disloyal bishops were arrested and tortured in Constantinople; ineffective governors were assassinated by locals. Then there was the increasing rivalry between Ravenna as the empire’s capital in Italy and Rome as ecclesiastical capital of the West. Furthermore, Ravenna was simply ignored for long periods by the authorities in Constantinople and Rome, as schism after schism erupted between the two, and the pope as bishop of Rome claimed with increasing belligerence to lead the Roman Church.

Fittingly for a scholar who has dedicated her career to the Eastern Roman Empire, Herrin is on Team Constantinople. Byzantium, we learn, combined the “ancient administrative, technical and legal capacities” of the Roman Empire with “the popular energies and theological claims of Christian faith, and the learning and culture of Greece,” giving it “an imperial system of exceptional self-belief, determination and inventiveness.” It was the eastern emperors who “provided the shield that excluded Islam from further advances into the west,” resisting Arab sieges in 667–669 and 717–718. One might doubt that the Arabs who within two generations conquered a continuous territory from Afghanistan to the Atlantic lacked much in inventiveness, determination, or self-belief, but that’s the problem: if Constantinople had fallen to the Arabs, they would also have taken Rome. It would be churlish to observe that Arabic scholarship might have saved the city from the Dark Ages; “without Byzantium,” Herrin explains, “there would have been no ‘western Europe.’”

The end came fast all the same, prompted by imperial demands on Italy for more taxes in the 720s and a bout of iconoclasm in Constantinople beginning in 730. Both Rome and Ravenna refused to go along with the destruction of holy images, and the barbarians seized their opportunity, finally and decisively severing Western Europe from the Roman Empire. In 751 Roman Ravenna fell to the Lombards without a battle; five years later it was taken from them by the Franks, the rising power of northwestern Europe, in the name of the pope.

Herrin neatly describes the way the political world shifted in the eighth century: in place of a fundamentally east–west dynamic in diplomacy, religion, and military affairs, north–south relationships took hold: tension between Constantinople and a new caliphate based in Baghdad alongside an alliance between the Franks and the bishop of Rome, in the guise of a new and “holy” Roman Empire led by Charles the Great, king of the Franks. It was Charlemagne who lowered the final curtain on Ravenna’s imperial history, enthusiastically removing marbles from the city for his new capital at Aachen, five hundred miles north. There he based his palace chapel on the church of San Vitale and installed beside it another of Ravenna’s treasures, an equestrian statue of Theoderic, a model for a powerful and learned barbarian king.

Ravenna was left to fester gently. As the port decayed and the channels of the Po silted up, the traders moved north, first to the island of Comacchio and then to Venice, whose merchants established themselves in Constantinople, Alexandria, and the Islamic ports of the Levant.

This is where Herrin’s story ends, and there’s not much more to say. Dante lived in Ravenna for several years before his death in 1321 and is buried there in an ancient Roman sarcophagus. The city was besieged by French forces in 1512, when cannon fire damaged Theoderic’s porphyry grave tub. By the eighteenth century most Grand Tourists passed Ravenna by, and those who made the trip spent more time describing the problems of the journey than the antiquities they found upon arrival. They barely mentioned the mosaics at all, although one traveler did note that the floor of Theoderic’s mausoleum was underwater.3 Now the city lies seven miles inland, the ancient canals have disappeared, and Ravenna is still hard to see.