If you’ve wandered through Testaccio, you’ve probably noticed the lopsided hill rising up behind the trattorie and more than a few auto body shops. That’s Monte dei Cocci, or Monte Testaccio, and it’s not a natural formation. It’s a trash heap. A two-thousand-year-old, half-mile circumference, 120-foot-high mound made entirely of broken amphorae, tens of millions of clay jugs that once held olive oil shipped to Rome from across the empire.

Back when Rome ran on imports, this neighborhood was the site of the city’s river port. Olive oil came in mainly from what’s now Spain and Tunisia. Wine amphorae could be reused. Olive oil amphorae? Not so much. The porous clay soaked up oil, went rancid, and couldn’t be cleaned. So the Romans smashed the amphorae and stacked the shards in an orderly landfill. Layer upon layer, century after century. Lime was sprinkled between the fragments to control the smell and keep pests away. Over time, this well-organized dump became a man-made hill and a monument to infrastructure and appetite.

Monte Testaccio sat mostly ignored through the Middle Ages. No one knew quite what to do with it. But it didn’t go to waste. In the tenth century, it hosted religious processions. By the fifteenth, it had become the centerpiece of Carnival festivities: Think Roman Mardi Gras chaos, horses, and plenty of wine. During the Renaissance, it got a second life in the food world. Its clay-packed interior stayed cool year-round, perfect for carving out wine caves. Osterie and wine merchants set up shop in its belly, aging their barrels in ancient trash. In the twentieth century, the hill pivoted again, this time to nightlife. Locals turned those wine caves into taverns and, later, clubs. DJs, discos, and dancing, all set to a backdrop of terra-cotta shards. Some of those same caves are still in use today, their damp stone walls a direct link between Testaccio’s Roman past and its food-loving present, now home to a Peruvian chicken spot, a butcher, trattorie serving offal-centric classics, and even a cheese cave.

Archaeologists started taking Monte Testaccio seriously in the nineteenth century. Heinrich Dressel’s amphora typologies, especially the chubby Dressel 20 jars from Baetica (southern Spain), mapped the city’s olive oil supply chain in amazing detail. Later scholars, like Emanuele Greco and José Remesal Rodríguez, expanded on that work, tracing how shifts in amphora shapes reflected changes in trade and imperial policy. It’s rare to find a site so intact, so specific, and so revealing about how a trade network really worked.

Today, Monte Testaccio is fenced off, but you can still see its slopes from the street—or on a private visit with me—crumbly, layered, and unmistakably ceramic. The rest is obscured by hundreds of species of plants that flourish on the hill, a new life for a rather impressive trash heap.