No one really knows where it started, but it's spread all over the world in the past few years—"Love Locks" snapped onto railings, especially on bridges.
Some hate them and feel they disfigure spaces with other purposes (in Basel, we found them on a chapel marking the spot where women suspected of witchcraft were drowned!) Some swoon over the romantic idea of sealing love with a padlock and throwing the key into the water so love can never be undone (although that does raise the spectre of an unhappy couple bound together).
And some, like me, have trouble deciding. On the one hand, it's tawdry, ugly and self-assertive (and in some cases, including the Pont des Arts, can damage the site); and the proliferation of lock vendors at both ends of the bridge is annoying—but there's something about some of the couples, and something about some of the messages, that keeps me from complete anger.
Oh, about the damage: Part of the railing in this picture collapsed a few months later under the weight of the locks. Paris Mayor Anne Hidalgo ordered the locks removed—but also appointed officials to find somewhere for couples to put their locks. Tourist-savvy, no?