Spolia

ROMAN MARS: This is 99% Invisible. I’m Roman Mars. 

In South Liverpool, there’s a neighborhood called Granby. It used to be one of the most vibrant and diverse neighborhoods in the UK. It had a busy main street lined with shops and cafes. But by 2012, when an architect named Lewis Jones first visited, most of the houses were unoccupied. 

LEWIS JONES: So, you know, a couple of hundred houses, but only about 10 or 12 people still living there. The rest of the houses–all empty. 

DELANEY HALL: Granby had suffered through decades of unemployment, aggressive policing, and failed redevelopment schemes. And over time, the neighborhood had hollowed out. 

ROMAN MARS: That’s 99PI senior editor Delaney Hall. 

DELANEY HALL: The local government had forced residents to sell their homes and then boarded them up. But before the authorities sealed each house, they gutted it. 

LEWIS JONES: They’d strip everything out. They’d strip out the copper, the lead, everything that was seen to have an economic value, but also everything that would enable someone to live there, the toilets, the kind of infrastructure. And that was to prevent people from squatting in those houses after they’d been emptied out. 

DELANEY HALL: And after stripping the houses and boarding up the windows, the government would place a sign on the front, reading…

LEWIS JONES: “All items of value have been removed from this property.” And, you know, it’s quite a provocation when every single house on the street says on it, “No items of value in this house.” 

DELANEY HALL: Of course, the government meant materials like copper and lead. But there are other kinds of value embedded in a home. There’s the skill it took to build it and the years of life that happened inside of it and the community that grew up around it. And what happened next in Granby would prove the signs wrong. 

ROMAN MARS: A small group of residents basically refused to leave the neighborhood. Little by little, they began clearing trash from the empty lots, planting community gardens, and painting the boarded up houses in bright colors. 

DELANEY HALL: Eventually, this band of holdouts formed a community land trust, or a CLT. Their goal was to take ownership of the empty houses and bring people back to the neighborhood. They raised money through a patchwork of small grants, and then they realized it might be useful to have some folks on board who knew how to design and build stuff, which is how Lewis got involved. 

LEWIS JONES: They wanted to renovate those houses. They wanted to provide those as affordable housing. They wanted to invite people who previously had lived in that neighborhood but had to be moved away from it. They wanted to invite those people back in. 

DELANEY HALL: Lewis is a part of a design collective called Assemble. And with Assemble’s support, the CLT advocated to the local government to stop demolishing the remaining homes. Then, they worked together to renovate a handful of the old houses. 

ROMAN MARS: As they pulled out materials that were too damaged to save, they started experimenting with the debris. Eventually, they set up a little backyard workshop with a local artist. And together, they figured out how to make something that they called Granby Rock. 

LEWIS JONES: And it was basically a kind of rubble terrazzo that we’d take all of the broken bricks and bits of slates and other kind of debris coming out of the renovation process and we’d recast them as components for these new decorative fireplaces and mantelpieces that we then put back into each house. 

DELANEY HALL: Every chunk of Granby Rock was unique, swirled with color from the old bricks and flecked with pieces of broken slate. Then it was poured into molds and polished smooth. Granby Rock fireplaces and countertops went into each of the renovated houses. 

LEWIS JONES: It just felt important as part of kind of the process of reclaiming the narrative of these houses–of this neighborhood–that actually valuing everything that was there was important. 

ROMAN MARS: Over the next few years, dozens of properties in Granby were renovated and then offered as affordable housing. And slowly, people started moving in. 

DELANEY HALL: New families prepared dinner on the countertops made from salvaged brick. They sat near fireplaces that were cast from the rubble of the house next door. They were living in a very real way with materials from the neighborhood’s complicated past. 

ROMAN MARS: In the world of design, there’s a term that’s used for the practice of taking elements from older buildings and reusing them in new ones. It’s called “spolia.” And what Assemble did in Granby was a version of that. The designers looked at the materials from the old houses, and they saw an opportunity to make something new. 

DELANEY HALL: Reuse has always been an element of how humans build. We are endless recyclers, pulling nails out of old burned timbers and cleaning and restacking used bricks and hauling stone from one building to the next. 

ROMAN MARS: But with Spolia, this reuse isn’t just a matter of practicality. It also carries meaning. The old material has a history, and using it in a new building is a way of acknowledging that what came before still matters. And that might be why spolia shows up in some of the world’s most famous architecture, places like the Hagia Sophia, Notre Dame, and the Great Mosque of Córdoba all use repurposed stonework. 

DELANEY HALL: But to really understand spolia, you have to go back to the place where the practice first became widespread. It happened when a civilization was in the middle of an existential crisis. And it started pulling apart the old world in order to build a new one. That civilization was the Roman Empire. 

ROMAN MARS: That’s funny, I was just thinking about the Roman Empire. 

DELANEY HALL: At its peak, the Roman Empire controlled the entire Mediterranean world. It spanned Europe, North Africa, and Western Asia. The empire lasted for roughly five centuries, and nearly 2,000 years later, we are still arguing about its legacy. 

EMMA SOUTHON: So my name is Dr. Emma Southon. I am a Roman historian, I am an ex-academic, and now I write books about how horrible the Romans were. 

DELANEY HALL: Emma loves to hate the Romans. She has been obsessed ever since she first learned about them as a teenager. 

EMMA SOUTHON: The thing that I love the most about them, more than any other empire really, is the complete disconnect between their image of themselves as being the most rational, the most perfect, the peak of civilization, the best that humanity can be, combined with the actual reality of what their empire was, which was a horrifically violent machine that chewed up land, chewed up resources, and produced marble buildings and emperors. 

DELANEY HALL: The Romans projected power through architecture. Emperors built enormous monuments to prove that they were rich and legitimate. 

ROMAN MARS: Emperor Augustus famously claimed that he “found Rome a city of brick and left it a city of marble.” Hadrian built the pantheon. Trajan built his famous column. The Flavian emperors made the Colosseum. 

DELANEY HALL: In fact, pretty much all the Roman emperors that we’re familiar with today are the ones who left behind something monumental because that was the whole point of building the monuments in the first place. The Romans were always thinking about the future. They were always imagining us, 2,000 years down the road, marveling at what they created. 

EMMA SOUTHON: As soon as they can afford to build an expensive stone, they do build an expensive stone because they know it will last and they’re always producing for the generations in the future to make sure they will be remembered. 

DELANEY HALL: The most expensive, durable, monumental stone to build with was marble. And Romans quarried it from all over their empire. They got green marble from Greece and red porphyry from Egypt. These Roman quarries were state-owned, and they relied mostly on slave labor. They were located in hot, dry places. And they were all overseen by the army. It was terrible backbreaking work. 

ROMAN MARS: After mining the marble, the Romans shipped it across the Mediterranean and used it to build the kind of magnificent structures they became famous for. 

DELANEY HALL: And that’s how it went for many centuries. The Romans built monuments to show how awesome they were, using rare stone from far-flung places, and the message it conveyed was clear. Rome was eternal. Until it wasn’t. 

ROMAN MARS: Starting around the middle of the third century, the Roman Empire got hit by a series of overlapping catastrophes. Each one made the next one worse. This wasn’t exactly the fall of Rome, it was more like the stumble. 

DELANEY HALL: First, there was political chaos. 

EMMA SOUTHON: People keep murdering the emperor and then declaring themselves emperor far, far away from Rome. And it’s very chaotic, and there’s no stability at the top. 

ROMAN MARS: Meanwhile, the empire’s neighbors were watching this political instability, and they’re thinking, “Hey. There’s an opportunity here.”

EMMA SOUTHON: Everybody around the outside of the empire thinks this is a great time to try and have a go at taking some land for themselves. You start to get non-Roman peoples trying to get inside the empire. 

DELANEY HALL: Then a pandemic hit. It was called the Plague of the Cyprian and it was horrific. For almost 20 years it ripped through the empire. Some scholars now think it was a virus similar to Ebola.

EMMA SOUTHON: And it was killing thousands of people a day for 20 years in seasonal cycles. 

ROMAN MARS: And then the climate was also changing. The agricultural parts of the empire experienced terrible droughts. The Nile stopped flooding, crops failed, people starved. 

DELANEY HALL: Oh, and then there was hyperinflation on top of everything else. And these various crises went on and on for decades. 

ROMAN MARS: Needless to say, nobody was really looking after the Romans’ magnificent marble buildings during this absolute cluster [BLEEP] of a half century. There was a lot of deferred maintenance, while people dealt with hemorrhagic fevers and famine and invasion from all sides. 

EMMA SOUTHON: Nobody has been replacing broken tiles or polishing the tiled floors or putting the mosaics back together.

DELANEY HALL: The result was that, in Rome, there was a lot of beautiful, expensive marble just sitting there, slowly falling apart from neglect. 

ROMAN MARS: At the same time that was happening, Rome’s quarries in Greece, Egypt, and North Africa were becoming really hard to access. Travel and trade was much more dangerous. That meant if you wanted to build something impressive–and the Romans always did–you couldn’t just order up some new marble. 

DELANEY HALL: The Romans were in a bind. Their colossal old monuments were falling down, and they couldn’t get the material to build new ones, until finally one guy connected the dots. He realized that you could use those old buildings as raw material to build new stuff. His name was Constantine. 

EMMA SOUTHON: By the time Constantine kind of comes and unites the Empire, everybody is very ready for a savior. 

ROMAN MARS: Constantine grew up a soldier, and he spent nearly 20 years fighting one civil war after another, until finally he controlled the entire empire. Then he proceeded to transform it. He legalized Christianity, for one thing, and, most relevant to our story, he launched an enormous wave of construction. And like every emperor before him, he understood the power of architecture. 

DELANEY HALL: And so did the people around him. Not long after his bloody ascent to power, the Roman Senate gave him a gift, a huge triumphal arch right next to the Colosseum. 

EMMA SOUTHON: I have Constantine’s Arch tattooed on me because it’s the quintessential arch. 

DELANEY HALL: The monument was officially a celebration of Constantine’s rule. But Emma says the Senate had its own more self-interested reasons for building the big, beautiful arch. 

EMMA SOUTHON: Which is the kind of thing you do when you have an emperor who kills a lot of people. You give him the biggest arch. You give him anything that will make him happy and hopefully not turn his really big successful army against you at any point. 

ROMAN MARS: The arch was covered in panels with sculpted scenes on them. But many of those panels weren’t originally made for Constantine. They were taken from monuments honoring emperors who’d lived around 200 years before. This was partly a matter of practicality because it was hard to get enough new marble to make the arch from scratch. But maybe more importantly, it was a symbolic move because, in a narcissistic twist, the images of the old emperors had been reworked to look like Constantine. 

EMMA SOUTHON: A sculptor has gone in and subtly reshaped the face because he’s got quite a distinctive head, Constantine. So they had made his big square head and put that onto the original. 

DELANEY HALL: This effectively made it look like Constantine, with his big square head, was doing all the stuff that past emperors had done, like riding a horse over the bodies of his enemies or addressing a crowd of troops or hunting a lion. The idea was to remind people of when Rome was great. 

EMMA SOUTHON: To evoke a memory of Rome at its healthiest, at its most prosperous. So it is a specific and deliberate choice to make that clear connection back to a kind of lost golden past. 

DELANEY HALL: Constantine’s Arch was a masterpiece of political messaging, and it was also a turning point in the history of architectural reuse. There has been some debate among scholars about whether the repurposing of the panels was artistic or just practical. But a lot of them think it wasn’t just recycling to cut costs. It was meant to communicate something about the new political moment. 

ROMAN MARS: A column pulled out of a pagan temple still has an aura of prestige. A carved panel from Rome’s Golden Age still carries a certain authority. Constantine understood that if you place those materials in a new context, all of that accumulated meaning could be deployed in new ways. It was reuse as propaganda. 

DELANEY HALL: Constantine’s reuse also set a new precedent. Once the emperor himself started pulling apart old monuments to build new ones, it gave permission to the rest of the empire. It became this interesting and legitimate thing to do. And soon this kind of reuse was spreading. People started salvaging old columns and decorative friezes and ornamental stonework. They would pull that material out of old buildings and use it in new construction. 

ROMAN MARS: And a lot of that new construction was churches. Constantine had legalized Christianity, and now the faith needed a lot of grand new buildings to match its status as a legitimate religion. Huge basilicas went up across the empire, and they needed marble. Thankfully, there were crumbling pagan temples everywhere, full of the kinds of stone that would make churches look amazing. 

EMMA SOUTHON: And it becomes about the power of the church on Earth to show that this is God’s Earth and we can decorate his house with all of the beautiful things. 

DELANEY HALL: The other thing that supercharged this new wave of architectural reuse was that Constantine had founded a new capital, named for himself, in Constantinople. And much of the new building in Constantinople involved materials salvaged from other places. 

EMMA SOUTHON: When he founds Constantinople, he sweeps around the empire, taking up cool stuff from other places, basically, in order to decorate his new city, much to the stress of everybody else. 

DELANEY HALL: A lot of people were not thrilled about the old marble temples being pulled apart. Especially in Rome, it sometimes felt like the city was being taken apart piece by piece. 

EMMA SOUTHON: Everything that we know about what ordinary people saw about it is that they hated it. 

DELANEY HALL: People actually rioted. They were so fed up that their neighborhoods were starting to look ramshackle and just bad. 

EMMA SOUTHON: “That was a nice building that was in my neighborhood, and it had really nice columns on it. And now it doesn’t have any columns and the roof is falling down. And nobody’s going to do anything about that.”

DELANEY HALL: They needed the equivalent of a Roman HOA, some enforcer who might keep up the standards of the neighborhood. And eventually, about 50 years after Constantine basically invented this kind of reuse, later emperors were passing laws trying to stop it. If you were caught stealing stone from buildings, you could be fined. But the laws were pretty toothless, and it kept happening anyway. And this tension never really went away. There were the people who wanted to preserve the old buildings, and then there were the people who wanted to strip them for parts. 

ROMAN MARS: In fact, that tension eventually became embedded in the word that we use for the practice. The term “spolia” was coined during the Renaissance, when researchers of the time had rediscovered Classical Rome and fallen in love with it. And when they noticed that beautiful ancient Roman stonework had been salvaged and then wedged into medieval church walls, they were disgusted. It looked to them like the church had pillaged the ancient world. They coined the word “spolia” from the Latin for the “spoils of war.”

EMMA SOUTHON: To describe this process, to make it into a process of war, of almost attack on these old buildings… The use of “spolia” starts as a renaissance moral judgment on what has happened. 

DELANEY HALL: But over time, the term lost its moral sting. 

EMMA SOUTHON: And now, in academic writing, it is just used as a neutral descriptor. 

DELANEY HALL: Spolia outlived the empire that made it famous. Wherever the Romans built stuff, later civilizations found their materials and put them to new uses. Roman tiles showed up in medieval churches in England. Charlemagne installed Roman stonework in the chapel in his palace. And across the Islamic world, mosques were built with columns salvaged from Roman temples. But spolia is really just one expression of a much older and more universal human instinct to reuse. After the Second World War, for example, when European cities lay in ruins, people picked through the rubble and used what they found to rebuild. That wasn’t really spolia because it wasn’t about symbolism. It was just necessity. But still, the underlying logic was the same. For most of human history, reuse wasn’t some special thing. It was just how people built. 

ROMAN MARS: But it’s not how people build anymore. That’s when we come back. 

[AD BREAK]

ROMAN MARS: Today the vast majority of construction involves demolishing what’s already there and starting from scratch, with all new materials that are uniform and predictable, with no history and no variability. It’s often cheaper and more efficient than reusing the old stuff. 

DELANEY HALL: But now, a growing number of architects and researchers think that reuse is a practice we need to relearn because it turns out that making everything from scratch, with raw materials, is something the planet can’t sustain. 

KATE SIMONEN: As we look into the future, we’re not going to be in an extract and throw away world. 

DELANEY HALL: This is Kate Simonen, a professor of architecture at the University of Washington. 

KATE SIMONEN: I mean, by requirement, we’re going to need to reuse the things that we have made previously, otherwise ultimately we would run out. 

DELANEY HALL: The labor and fuel expended in creating even a single brick are enormous. And Kate says that it’s worth sitting with what it actually takes to make something new. 

KATE SIMONEN: So in order to make a brick, you have to excavate the clay material from the earth. And in doing that, you’re using an excavator that’s burning diesel. And so as you’re burning that diesel, emissions go up into the atmosphere. 

DELANEY HALL: So that’s step one, just digging the clay out of the ground. Then you have to shape it, and that’s often done with a machine. 

KATE SIMONEN: And that machine might be using electricity. Making that electricity has emissions. 

DELANEY HALL: Then the brick needs to be cured. And that usually means burning natural gas to fire the kiln. 

KATE SIMONEN: And that natural gas then releases emissions into the atmosphere. 

DELANEY HALL: And finally, you have to transport the brick to wherever it’s needed, which requires a truck or a train or an airplane. 

KATE SIMONEN: And that then is also, again, likely burning diesel, which releases emissions. 

DELANEY HALL: Now consider every brick, every steel beam, every panel of drywall, and every pane of glass in every building in the world. There’s just an enormous amount of materials and labor and what’s called embodied carbon in the built environment. 

ROMAN MARS: Which is why a growing number of architects and engineers argue that we basically need to practice spolia at scale. 

DELANEY HALL: And that sounds like a great idea, but it’s actually very hard to do. When you salvage something like an old steel beam, it’s hard to know exactly what you’ve got, like what it’s made of and what loads it can carry. There is no reliable supply chain for reclaimed materials, at least not at the scale we really need. 

ROMAN MARS: And most buildings aren’t designed to be taken apart. It takes a lot of time and effort to deconstruct an old building piece by piece so that the parts can be used again. 

KATE SIMONEN: How we make buildings today has influence on how easy they will be to take apart in the future. And not that many building owners today are asking their design teams to make it easy to tear down my building in 60 to 80 years. That’s not really their top priority. 

ROMAN MARS: In other words, it’s hard to get out of that emperor mindset that buildings must last forever. 

DELANEY HALL: There are some traditions that better understand a building’s transience. For example, Japanese temples used to be built without nails or screws. Instead, they were supported by interlocking wooden joints so that they could be taken apart and reassembled. And there are modern examples too, like the Olympic Village during the 2024 Paris Games that was designed to be converted to housing after the competition. So there are buildings, here and there, being designed with their next life in mind. 

I asked Kate what she thought about the Roman connection, how they took their crumbling buildings and used them as raw materials for something new. 

KATE SIMONEN: I think those buildings actually had fallen apart. They were the debris of previous civilizations. And so, ultimately, our lives will be the debris for other civilizations. 

ROMAN MARS: There are a lot of ways to think about what makes building materials valuable. Kate thinks about it in terms of scarcity. The earth is finite. There’s not an endless amount of clay, sand, and stone. We have to be careful not to exhaust the materials we have. 

DELANEY HALL: The Roman emperors thought about value in terms of prestige. Placing old materials in new contexts allowed them to communicate something about continuity and power. 

ROMAN MARS: And the residents of Granby, in South Liverpool, measured value in a different way. They cared about the history of their neighborhood. And when they worked with Lewis Jones and the team at Assemble, they didn’t just see old and dilapidated houses. They saw the raw materials for something new. 

DELANEY HALL: Granby Rock, the product they made from the neighborhood’s debris, was a way of insisting that the community still had worth. 

LEWIS JONES: It was important to put these things into the houses that would express the love and care and attention that had gone into renovating them. 

ROMAN MARS: But since the early days of the Granby project, Lewis and his collaborators have started thinking much more about reuse in the context of climate change. The Granby workshop didn’t close when the renovation was finished. Instead, it grew into something bigger, a manufacturing studio in the neighborhood that’s still running today. It produces architectural tiles and ceramics out of recycled materials. They fire these tiles at lower temperatures to reduce their environmental footprint. And they use electric kilns. 

DELANEY HALL: So, what started as spolia in the oldest sense has evolved into something more like what Kate Simenon advocates for. The workshop now helps other projects turn their construction debris into new building materials. It’s reuse that involves symbolism, but it’s also a practical recognition that we can’t keep extracting raw materials forever. 

LEWIS JONES: Every project always starts with trying to understand what’s already there and how to be really resourceful. And so reuse is a big, big part of that. 

DELANEY HALL: I asked Lewis what Granby looks like today, more than a decade after Assemble joined with the Community Land Trust to renovate the first houses. 

LEWIS JONES: Granby today still very much has the same spirit, I think, it had when I first visited 15 odd years ago. There’s still a kind of sense of wildness there. There’s still, like, furniture on the street. There’s plants in the pavement. There’s the odd painting on the wall, whatever it is. But obviously, amongst that, there are a lot more people living there now. 

DELANEY HALL: Lewis described kids playing on the streets where, not too long ago, every house had one of those signs–the ones that said, “All items of value have been removed from this property.”

ROMAN MARS: Those signs were, of course, wrong. The materials of the past are never worthless. 

99% Invisible was produced this week by Delaney Hall and edited by Emmett FitzGerald. Mix by Martín Gonzalez. Music by Swan Real. Fact-checking by Sona Avakian. 

Kathy Tu is our executive producer. Kurt Kohlstedt is our digital director. The rest of the team includes Chris Berube, Jayson De Leon, Christopher Johnson, Vivian Le, Lasha Madan, Joe Rosenberg, Kelly Prime, Jeyca Medina-Gleason, Talon and Rain Stradley, and me, Roman Mars. The 99% Invisible logo was created by Stefan Lawrence. 

We are part of the SiriusXM Podcast Family, now headquartered six blocks north in the Pandora building… in beautiful… uptown… Oakland, California. 

You can find us on all the usual social media sites, as well as our Discord server. There’s a link to that, as well as every past episode of 99PI, at 99pi.org.