Poetto is the beach of a city, and like a lot of city things it has been loved hard, managed badly, and argued over for decades. It is the eight-kilometer main beach of Cagliari, the capital of Sardinia, running from the limestone headland of the Sella del Diavolo to the edge of Quartu Sant'Elena, and for most of the last century its fame rested on a single quality: a powdery, brilliant white sand that Cagliaritani considered among the finest anywhere. The central story of modern Poetto is how that sand was lost, and how the attempt to restore it became a scandal.

The slow erosion. The trouble began with a loss of character. For decades the beach was lined with casotti, colorful wooden huts that were half changing-room and half miniature beach house, an institution of Cagliari summers. They were removed entirely in 1986 for sanitation reasons, and their disappearance, together with overcrowding and an absence of serious erosion-prevention work, set off a gradual dispersal of the beach's sand and a faster rate of erosion. The famous white strand started, quietly, to thin.

The fix that became the scandal. In 2002 the authorities acted, with a renourishment, the ripascimento in local usage. The plan was straightforward beach engineering: dredge sand from deeper water and spread it along the Cagliari end of Poetto to rebuild the lost width. The execution created a problem larger than the one it solved. The imported sand was darker, coarser, and of a completely different consistency than the fine white sand the city had grown up with, and it changed the look of Poetto visibly and immediately. The reaction was furious, and unusually concrete: the administration that approved the project was taken to court for damages. Poetto had been handed back some of its width and stripped of its color in the same operation, and the episode became a defining argument in the city's relationship with its own beach. Erosion has continued since, with reports of the beach losing on the order of a meter of sand a year and storms delivering fresh damage, so the renourishment did not even settle the underlying problem it was meant to fix.

The headland and the legend. The western end of the beach is anchored by the Sella del Diavolo, the Devil's Saddle, a saddle-shaped limestone promontory wrapped in a legend of a battle between an angel and the devil and topped by an old tower, the Torre del Poetto, that one account credits with giving the beach its name. Below it sits Marina Piccola, the small harbor that closes the Cagliari side. It is the dramatic, photogenic counterweight to the long flat sweep of the strand.

The pink behind the beach. And then there is the part of Poetto that has gone right, which is across the road and is pink. Directly behind the beach lie the Molentargius salt pans, a wetland in the middle of a metropolitan area, now a protected regional park, where Greater Flamingos have bred since 1993, in the thousands of pairs. Together with the Camargue in France and Fuente de Piedra in Spain, Molentargius is one of the three most important flamingo breeding colonies in the western Mediterranean, and the birds fly over the city and the beach between the salt pans and the sea. Cagliari has earned its informal title as a city of flamingos. They are visible from the beach itself, a wild pink commute against an urban skyline, an everyday sight few other European capitals can offer, and a reminder that the same shoreline holding a failed sand experiment also holds a thriving wild colony.

Why it matters. Poetto is worth a page precisely because it is not a pristine wonder but a real, contested, working city beach, and because the few hundred meters from the waterline to the salt pans contain two opposite environmental stories at once. On the seaward side is a cautionary tale: a beloved beach whose defining white sand was eroded away and then, in trying to fix it, recolored into something the city sued over. On the landward side is a quiet triumph: a protected lagoon that has produced one of Europe's great urban flamingo colonies. The honest Poetto is both, the darker sand and the pink birds, the lawsuit and the conservation success, held together on one shore. It is less beautiful than its old postcards and far more interesting than them.