The Seine riverbanks in central Paris are a walkable ribbon of stone quays and bridges, running from the Pont de Sully to the Pont d'Iéna past the island where the city began. You walk the lower quays, at water level, closed to cars since the 2010s and handed back to strollers and sunbathers. Down there the traffic drops out of hearing. Each bridge frames its own view: Notre-Dame's flying buttresses, the long facade of the Louvre, the gold dome of the Invalides.
UNESCO lists these several kilometres of quays, walls and bridges as a single World Heritage site. The spans cross four centuries. The Pont Neuf, whose name means new bridge, is the oldest still standing, finished in 1607; the Pont Alexandre III went up all gilded figures and lamp-posts for the 1900 world's fair. Along the parapets the bouquinistes have sold second-hand books out of green boxes since the 1500s. On warm evenings the banks fill with picnics, glasses clink from moored barges, and a passing bateau-mouche throws light across the arches.