hey were expert engineers, way ahead of the curve on underfloor heating, aqueducts and the use of concrete as a building material. Now it turns out that the Romans were also masters at recycling their rubbish. Researchers at Pompeii, the city buried under a thick carpet of volcanic ash when Vesuvius erupted in 79 AD, have found that huge mounds of refuse apparently dumped outside the city walls were in fact “staging grounds for cycles of use and reuse”. Professor Allison Emmerson, an American academic who is part of a large team working at Pompeii, said rubbish was piled up along almost the entire external wall on the city’s northern side, among other sites. Some of the mounds were several metres high and included bits of ceramic and plaster, which could be repurposed as construction materials. These mounds were previously thought to have been formed when an earthquake struck the city about 17 years before the volcano erupted, Emmerson said. Most were cleared in the mid-20th century, but some are still being discovered. Scientific analysis has now traced some of the refuse from city sites to suburban deposits equivalent to modern landfills, and back to the city, where the material was incorporated into buildings, such as earth floors. With fellow archaeologists Steven Ellis and Kevin Dicus, who worked on the University of Cincinnati’s excavations, Emmerson has studied how the ancient city was constructed. “We found that part of the city was built out of trash. The piles outside the walls weren’t material that’s been dumped to get rid of it. They’re outside the walls being collected and sorted to be resold inside the walls.” Pompeii was a city of elegant villas and handsome public buildings, open squares, artisan shops, taverns, brothels and bathhouses. It included an amphitheatre that hosted gladiatorial games for audiences of up to 20,000. When volcanic dust from Vesuvius “poured across the land” – as one witness wrote – enveloping the city in darkness, at least 2,000 people died. In 1748, a group of explorers discovered the almost perfectly preserved city under a hardened carpet of ash and pumice. Even a loaf of bread was found preserved by later archaeologists. Pompeii is now a Unesco world heritage site and – in normal times – attracts 2.5 million visitors each year. Emmerson and her colleagues used soil samples to trace the movement of rubish across the city. “The soil that we excavate differs based on where the garbage was left originally,” she said. “Garbage dumped in places like latrines or cesspits leaves behind a rich, organic soil. In contrast, waste that accumulated over time on the streets or in mounds outside the city results in a much sandier soil. “The difference in soil allows us to see whether the garbage had been generated in the place where it was found, or gathered from elsewhere to be reused and recycled.” Some walls, for example, included reused materials such as pieces of tile and broken amphorae, and lumps of mortar and plaster. “Almost all such walls received a final layer of plaster, hiding the mess of materials within,” she said. “The idea has been that all this garbage resulted from that earthquake – consisting of rubble that had been cleared out of the city and dumped outside the wall to remove it from daily life. As I was working outside Pompeii, I saw that the city extended into developed neighbourhoods outside the walls ... So it didn’t make sense to me that these suburbs were also being used as landfills.” Modern approaches to waste management focus on removing rubbish from our daily lives, she added. “For the most part, we don’t care what happens to our trash, as long as it’s taken away. What I’ve found in Pompeii is an entirely different priority, that waste was being collected and sorted for recycling. “The Pompeians lived much closer to their garbage than most of us would find acceptable, not because the city lacked infrastructure and they didn’t bother to manage trash but because their systems of urban management were organised around different principles. “This point has relevance for the modern garbage crisis. The countries that most effectively manage their waste have applied a version of the ancient model, prioritising commodification rather than simple removal.” Allison Emmerson, who teaches classical studies at Tulane University, New Orleans, is the author of Life and Death in the Roman Suburb to be published next month by Oxford University Press.