The Greek orator Aelius Aristides, writing shortly after Hadrian had girded the entire Roman Empire with walls, credited Rome with a rather extraordinary achievement: the Empire, he declared, had brought an end to war. Accustomed only to peace, most Romans had come to doubt that wars had ever really happened. Reports of battle were dismissed as fairy tales. Civilians no longer worried that they might be called to arms. The entire population of the Empire had given up its weapons, entrusting its security to garrisons stationed on distant frontiers. Inside the walls, the Empire had become a sort of civilian paradise: the whole inhabited world, Aristides wrote, had turned to pleasures of every sort. Gymnasiums, fountains, temples, monumental arches, artists, and schools filled the cities. Absolute security, “universal and clear to all,” prevailed.
Aristides routinely tailored his opinions to please his audience—in this case, Hadrian’s successor, Antoninus Pius—but his glowing portrayal of the state of things in the mid-second century AD wasn’t entirely fiction. Most of the provinces had developed at least the rudiments of urban life prior to assimilation into the Empire, but only Rome, the improbable defender of civilization on three continents, had made such conditions universal: literacy, scholarship, monumental architecture, fine art, science—the accomplishments, in short, of a people who didn’t realize they were doomed. Rome temporarily freed the Western world from its fear of the warriors outside, and the result was a culture so prosperous that even those who most enjoyed it sometimes worried they had grown decadent.
The source of Rome’s security, and the key to its prosperity, was, to Aristides, obvious: walls, “unbreakable and indissoluble,” manned by countless ranks of soldiers, defended the state. The emperors had put up fortifications around “the entire world,” ranging from Ethiopia in the south to the Euphrates in the east and Britain in the north. Back in Italy, the capital city lay open because it had nothing to fear. Border walls—made of immense masonry blocks, according to Aristides—extended the same protection to all the cities of the Empire. Rome’s walls surrounded the Empire like a trench encircled an army camp.
Of course, we know that Aristides has gotten a few things wrong, and few of Rome’s frontiers were fortified by masonry walls, although perhaps the emperors preferred that their subjects believed they were. Most Romans never saw the vast array of towers, mounds, palisades, ditches, and forts that defended the frontiers, still less the soldiers who patrolled them. The borders were far away, and that distance added to the myth of invulnerability. Moreover, for those provincials who’d learned to accept Roman rule, the idea of enclosed borders wasn’t at all uncomfortable. Rome was too large to feel like a garrison state. If only it hadn’t all cost so much, if only there had been enough soldiers to man the walls, if only the walls could have held, Aristides’s walled paradise might have lasted indefinitely. As it was, Rome’s total security, “universal and clear,” didn’t even last until the end of Aristides’s life.
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In 2012, workers expanding a highway in Romania unexpectedly revealed the remains of a previously unknown Roman settlement, dating from the time of Aristides. Such discoveries, which can hold up projects for months, are a recognized construction hazard in Europe. They regularly frustrate contractors and developers, who can only hope the archaeologists will find little to extend the initial delay. The Romanian discovery, however, was extensive: a small town and its associated necropolis. All work was forced to a halt; bulldozers, graders, spreaders, and pavers were idled until archaeologists could excavate the site, officially dubbed Sibot-3.
From the start, the archaeologists had to work quickly, knowing that the road crew was anxious to resume work in good weather. In a perfect world, where archaeology is practiced only painstakingly and with infinite patience, the site deserved better. Sibot-3 was impressive in both its size and refinement. Here was one of those “border cities supplied with useful crafts and other adornments,” described by Aristides, the sort that flourished fearlessly in the shadow of the Empire’s fiercest enemies. Sibot-3 lay deep in Roman Dacia, a restive borderland that Hadrian’s aggressive predecessor, Trajan, had conquered. Yet even in this dangerous neighborhood, Roman life apparently prospered in the second century. Elegant buildings featured ornamental tiles. No fewer than seven workshops manufactured ceramics on a nearly industrial scale.
As a member of the team that excavated Sibot-3, I vividly recall my first view of the site. When our crew initially learned of the discovery, we were still domiciled well over an hour away, and the unexpected assignment required a long trip to the work site. For the first of several such commutes made before our relocation, we rumbled to the excavation in a dangerously overcrowded minibus, unair-conditioned in the hundred-degree heat, with windows closed in accord with Romanian custom. Puttering along local roads dotted with horse manure, on our way to the highways, we entertained ourselves with chatter that at least occasionally diverted our thoughts from the likelihood that we would arrive at the site as a busload of suffocated corpses. When we reached Sibot-3, still alive except for some brain cells that had starved for lack of oxygen, we unpacked our legs, sucked in great gulps of fresh air, and scattered across the grounds for a first look. By then, a few preliminary test pits had already been dug, and in all of them a thick black line formed a distinct horizontal stratum. This was unmistakably a burn layer, ashes from the destruction of Sibot-3 during the Marcomannic Wars of Marcus Aurelius.
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Marcus Aurelius (r. 161–80) assumed the throne just a few years after Aristides delivered his rosy account of the Roman Empire. The new emperor is generally said to have embodied much of what is best in civilization. A model philosopher-king, his stoic Meditations are still admired today. But Marcus was not fated for a life of peaceful contemplation. He was dragged into war by enemies from beyond the walls, and in the end his celebrated philosophical and scholarly pursuits never provided more than a temporary escape from a duty that pressed down hard on him. In AD 166, the Empire was invaded by barbarian Langobardi and Obii. The campaigns that followed saw Marcus defeated by Marcomanni and Quadi. Costoboci swept into Marcus’s beloved Greece, homeland of the philosophers who so inspired him, and sacked the ancient shrine of Eleusis. Who were these dangerous, unknown peoples? It didn’t matter. After Marcus, there would be no more philosopher-kings. Virtually all his successors were soldiers.
An epidemic ravaged Marcus’s Rome. It arrived courtesy of that distant Chinese wall that had linked together the far-flung empires of Eurasia. As it turns out, Wu’s wall had enabled more than just trade to pass between China and Rome. Chinese documents record Roman visitors to the imperial court during the time of Marcus. By then, China had already suffered its initial outbreak of that mysterious epidemic known to classicists as the Antonine Plague. Traders had apparently carried the disease to Mesopotamia, where it was contracted by Roman soldiers. Within a few years, an estimated 5 million people had died of plague in the Roman Empire, including a disproportionate number of soldiers on the frontiers. Aristides had once boasted that there were so many soldiers on Rome’s border walls that an arrow couldn’t pass through their ranks, but the plague now turned hyperbole into lie. Marcus Aurelius died in AD 180, leaving the borders more vulnerable than they’d ever been. His last words concerned the plague.
Marcus’s reign marked a turning point in the history of the Empire; the Hadrianic frontiers, with their walls, palisades, and ditches, had at last been overwhelmed. Throughout the provinces, a crisis of confidence threatened the very foundations of civilization. Signs of destruction, defeat, and decline mark the archaeological remains of second-century Roman cities, and not just the frontier settlements, such as Sibot-3. Deep in the heartland of Aristides’s walled Eden can be found whole towns entirely abandoned after violent demolition. Others suffered brutal destruction but survived. In Roman Lyons, the heavily settled hill of Fourvière was deserted. At Orange, one of the busiest neighborhoods—crowded with houses since the first century BC and honored with a grand public building in the first century AD—was abandoned, too. A shrinking Paris withdrew from its most far-flung neighborhoods. Second-century Tours suffered a contraction so severe that only two streets survived from the original plan.
Art historians have observed the changed mood that resulted from this first great failure of the Roman walls. Rome was the natural heir to the serene beauty of classical Greek art, but in the late second century that aesthetic skipped town altogether. A grim, violent sensibility replaced it. Many a Roman aristocrat went to his eternal rest in a stone coffin embellished by twisting, crowded, graphic scenes of war. Even Marcus Aurelius—he of the lofty ideals and philosophic spirit—inspired a massive column featuring sculpted images of barbarians being speared and beheaded. In several scenes, women are stabbed or dragged away. The Roman soldiers on the column resemble grinning ghouls as they go about their murderous work. It was an art to turn the stomach and sicken the soul, but an artist can only reflect the age in which he lives, and in this age the border wars had taken precedence over all that was elegant or beautiful.
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To students of Roman history, the third century is notorious: a numbing catalog of raids, border wars, and invasions that shocked and devastated the Empire. In AD 238, for example, barbarians destroyed the ancient Greek colony of Histria. Thirteen years later the Emperor Decius launched a campaign to halt Gothic raids across the Danube. Lured into swamps and annihilated, he was the first Roman emperor to fall in battle against a foreign enemy. Subsequently, the Goths acquired boats, sailed through the Bosporus into the Aegean, and raided the magnificent Greco-Roman cities on the coast of Asia Minor. They even destroyed the Temple of Artemis at Ephesus—a larger version of the original structure once deemed one of the Seven Wonders of the World.
Panic swept through Greece. The Peloponnesian Greeks attempted to insulate themselves from the horror by building a wall at the narrow isthmus that connected them to the mainland. They ransacked every public building within reach for stone. To their north, the Athenians, who had for so long put all their faith in Rome, repaired their city walls for the first time in over three hundred years. Their efforts came too late. Athens was sacked by the Goths, and even the buildings around the great central marketplace were burned and destroyed. Subsequently, the Athenians used blocks from the ruined Agora to build a protective wall around a small area north of the Acropolis. Broken segments of columns and sculptures were stacked unceremoniously in the new rampart. Glorious Athens, the home of tragedians, mathematicians, and philosophers, the city that had twice fought off the mighty Persian Empire, had lost its nerve. The city’s retreat into insignificance had begun.
To the barbarian invaders, all this frantic fortifying was unthinkable. Having been raised to esteem only those men who could achieve feats in arms, they watched with contempt as Romans hid behind walls. They taunted civilians whose hands had never held weapons and who wanted to avoid combat at all costs. The Romans, they declared, had more confidence in objects than in themselves. And in an insult that echoed the ancient letters of the doomed Bronze Age king Rib-Hadda, they ridiculed the Romans for living like birds in a cage.
Virtually no part of the Empire escaped destruction during this awful time. The Goths continued on to Italy. According to some of the more hyperbolic sources, they sacked five hundred cities along the way. Britain suffered heavily from barbarian raids. The provinces that sprawled from the Danube to the Balkans fared even worse. Three of the Empire’s most heavily defended regions were abandoned altogether, given up to barbarian occupiers. Gaul survived the turbulence of the third century, but just barely.
A forlorn practice testified to the sheer panic of civilized folk: in province after province, anxious civilians buried their money in pots under the ground, hoping to retrieve their fortunes in more secure times. Most never did. Countless such hoards remained exactly where they’d been buried, unretrieved and undisturbed, for nearly two thousand years until discovered by archaeologists or amateurs with metal detectors.
Rome itself wasn’t immune from the panic of the third century. The Eternal City hadn’t really, as Aristides claimed, eschewed ramparts, but it had theoretically been vulnerable since the fourth century BC, the last time it had updated its aging, inadequate defenses. Since then, the city had sprawled far beyond the circuit of its walls. In the early 270s, the Emperor Aurelian finally bowed to reality—reality, in this case, being the memory of a recent Alemannic invasion of Italy—and constructed new walls.
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As Rome went, so went the provinces. For nearly three hundred years, Roman cities had given little thought to protecting their citizens, relying, just as Aristides said, on faraway troops and eventually border walls to hold the frontier against the warlike peoples massed outside. Some cities, mostly the older ones, had outgrown their ancient walls. Others had never had any walls at all.
In the whole of world history, there had never been an experiment as grand as that of an empire composed mostly of unwalled cities. By leaving so many towns undefended, the Romans had adopted a comprehensive approach to local security—hundreds of miles of border walls and other barriers designed to create a massive, impenetrable shield over all Western civilization. In the aftermath of the third-century invasions, that all changed: the emperor Diocletian (r. 284–305) implemented a program to fortify the suddenly insecure cities of the western provinces. It was the last great construction boom of a city-building empire, and it was an act that repudiated every Roman belief in what a city should be.
With due deliberation, the wall builders dismantled those splendid, open cities that their fathers had created in earlier, more confident days. Buildings in the paths of the new walls were razed. Some were torn down simply to provide stone. In the rush to fortify the cities, the relentless chisels of the laborers broke apart tombs, temples, columns, baths, theaters, and amphitheaters. They tore friezes, relief sculptures, and capitals from their settings, using the bigger blocks for masonry and crushing the rest for rubble. Many an inscription, once intended to ensure immortal glory, was wrenched from its proper place to rest ingloriously among the bricks, masonry, and concrete of a rampart.
Late Roman construction possessed none of the exuberant confidence of earlier Roman urbanization. In the new work, luxury made way for pragmatism and toughness. The fourth-century townspeople of Bordeaux would have watched workers shoring up the banks of the Devèze River with fragments of ancient architecture, marble capitals, and columns. This was no time for sentimentality. Strong men were burying Bordeaux’s last urban monuments in the muck.
In cities everywhere, townspeople did what had to be done, making choices that would have seemed unthinkable during the early imperial period. In Paris, for example, miners cleared a densely inhabited area near the forum and dug shafts there for the extraction of gravel. In Fréjus, citizens succumbed to the pressure for space by sacrificing their public baths; they tore down the marbles and mosaics and reused the remaining structure for rough habitations. At Arles, excavators have discovered the fire-gutted ruins of houses, shops, and baths outside the walls. That area was reborn to a cruder existence in the fourth century, but few chose to live there. Late-Roman Arles could scarcely contain the timid masses who preferred a squalid but secure life within the walls to the more sumptuous suburban living of days gone by. The circus was transformed into a sort of apartment complex, and in the fifth century, the portico of the forum was leveled to provide material and space for housing. Townsfolk moved into mausoleums in the once-prestigious cemetery outside the amphitheater, a building that must have seemed far less imposing surrounded as it now was by lean-tos.
The wallers rebuilt their cities with a remorseless sense of purpose. Sprawling cities full of open spaces and beautiful monuments were reduced pitifully in size. Metropolises withered and shriveled up. The transformation is stunning—and even more so when we consider how it must have affected individuals sacrificing lifestyle for security. In Clermont-Ferrand, for example, a third-century aristocrat constructed a huge and impressive town house. We don’t know how long his family occupied their new home. Yet when the town retreated five hundred meters up the hill to a more defensible location, the house was carefully cleaned out, vacated, and left in the hands of workers who destroyed it. Likewise, in southern France, one family after another quietly evacuated five grand houses in the periphery of Aix-en-Provence. One by one, the families resigned themselves to the decline of their city. The stubbornness of the last inhabitants broke down only slowly, until at last a single household remained, alone, surrounded by empty buildings, in a curmudgeonly refusal to concede a diminished future. Eventually, that family, too, gave up.
Late Roman cities quickly acquired the look of fortresses, typically high, invariably walled, often surrounded by water. There is a strange déjà vu in seeing so many of the rebuilt towns conform to the same plan and surface area as their Iron Age predecessors. It was as if the squat fortress-towns of the Gallic world had simply fallen asleep for a while, dreaming of baths and amphitheaters, only to awaken some three hundred years later looking much the same as they had in the days before Caesar.
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It seems incredible, perhaps, but the shrinking cities of Spain, Gaul, Greece, and Asia Minor were luckier than many. They had, at least, survived. In the region once known as the Agri Decumates, only ghost towns remained. According to one Roman author, the Germans who moved into the area after Rome’s withdrawal avoided the abandoned towns as if they were tombs. On occasion, the triumphant barbarians would settle in the vacant country home of a departed Roman squire, but as if to underscore the defeat of civilization, many preferred to occupy prehistoric hill forts instead.
Roman civilization was in full retreat: provinces abandoned, fields deserted, art, literature, and science put on hold. The once gorgeous towns with their gleaming triumphal arches had shrunk into toughened little nuts, but even these soon became targets of raids. In province after province, the barbarians found their way around the border walls, probing imperial defenses much in the way that water, spilled on a floor, flows to the lowest level and finds its way through cracks. Often, the Hadrianic defenses forced the barbarians to detour through unwalled provinces that had previously been considered safe. As early as Marcus Aurelius’s time, the establishment of barriers near the mouth of the Danube had redirected steppe raiders through the Carpathians, spelling doom for settlements such as Sibot-3. Later emperors paid greater attention to these detours. Walls begat more walls, but it was already too late.
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In AD 284, a Roman embassy arrived at the Chinese court. Ordinarily, transcontinental business was conducted by middlemen, and these ambassadors may have been the first Romans to pass through the old Han walls since the days of Marcus Aurelius. When the embassy returned home, it reported to a new emperor. We may never know if Diocletian was influenced by tales of the Chinese wonders, only that he apparently ordered yet another round of border walls.
New border walls soon crisscrossed the map of southeastern Europe. Viewed from a distance, it is almost as if one can see a giant hand at work, placing lines here and there to plug up holes in the old Hadrianic frontiers. In northwest Dacia, the Romans blocked gaps in the Carpathians with earthen and stone barriers. South of the Carpathians, they established vast earthworks—the so-called Devil’s Dykes—stretching well over four hundred miles. Taken in combination with another early-fourth-century earthwork, the nearly three-hundred-mile-long Brazda lui Novac, Roman barriers completely encircled the lower Carpathian Mountains.
Diocletian may have built more than he could defend, and as the fourth century progressed, his successors abandoned the long lines of southeastern Europe and concentrated on shorter lines closer to the two capitals. Constantinople was given protection by a new twenty-seven-mile wall that bisected the gateway of the steppe in a region of modern Bulgaria well south of the ruins of Tomis. Italy, meanwhile, was fortified by a system of walls blocking the various passes through the Julian Alps. All told, the latter fortifications totaled around forty miles of walls, guarded by soldiers occupying some seven hundred towers. These closed off key choke points in the routes through Slovenia, Croatia, Austria, and Italy.
In the Rhineland, which had never been walled owing to the defensive properties of the flowing river, the collapse of the frontier came so quickly that the Roman soldiers never had an opportunity to construct new walls, if any were ever contemplated. By one count, some forty Rhineland towns were ravaged by Germans during the reign of Constantius II (r. 337–61), even while steppe peoples overran the Danube. This was some two hundred years after the great projects of Hadrian. The wooden palisades that had once stretched for hundreds of miles had all rotted away.
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By the late fourth century, the great prosperity once celebrated by Aristides existed only in memory. Hadrian’s walls had failed. Civilization was under siege. Fear had returned, and with it came all the ugly transformations of a society placed perpetually on a war footing. The Empire devolved into little more than a totalitarian state. In earlier times, happier, brimming with humor, and vibrant with opportunity, Roman satirists had lampooned a lively capital filled with quack priests, queer foreigners, flamboyant fashionistas, and slaves-turned-millionaires. By contrast, the later Empire regulated religion, dictated which nationalities could intermarry, and required people to remain in the occupations held by their fathers. Imperial edicts forbade long hair and even specified the sort of clothes Romans could wear. Onerous taxes left citizens destitute. Some fled to the barbarians to escape collection. Those who remained were at the mercy of tax men who seized not just money but also women’s jewelry and even clothing, right down to the underwear.
What drove Rome to these extreme measures was the sheer cost of walling off its civilian population and defending it against the barbarians. It was a cost that threatened to destroy the economy of the Roman world. By the mid-third century, the cash-starved emperors had so debased the currency that Rome’s “silver” coin, the denarius, contained no more than 5 percent of the precious metal. Emperors complained that the army could no longer be fed or clothed. Taxpayers complained that the cost of the army was crushing them.
How do we assess the impact of Rome’s participation in the Great Age of Walls? It would be easy enough to manufacture a cost-benefit analysis slanted to prove whatever thesis we like. Hadrian’s walls do seem to have temporarily secured the Empire, making possible an age of productivity, creativity, and prosperity, during which civilians did not have to fear for their lives. But those same walls required tens of thousands of border guards, perhaps hundreds of thousands, necessitating that Rome rely heavily on foreign mercenaries, whose leaders would eventually turn against the Empire. And perhaps Rome would have required even more mercenaries if the emperors had never built any walls at all.
A thousand questions still beg to be answered: Did Rome’s walls deter barbarian aggression or provoke more of it? Would the Hadrianic fortifications have held out if only the Antonine Plague hadn’t denuded the walls of their defenders? Were the ancients correct in believing that warriors living behind walls eventually lost their edge? History has a maddening habit of raising more questions than can be answered. As the Great Age of Walls reached its climax in the West, the questions only multiply.