A relatively new phenomenon (for Paris), the Pont des Arts bridge has gotten covered with “love locks” since about 2008.
If you’re not familiar with the meme, the idea is that couples write their names on a padlock, lock it on the bridge, then toss the key into the Seine river as a show of their everlasting devotion. The problem, though, is that the bridge wasn’t really designed to handle this kind of a load (it’s estimated that nearly a million locks, weighing 60+ metric tons, have been snapped onto the bridge).
In 2014, part of the bridge’s railing collapsed from the collective weight of locks, and much of the railing is now covered in plywood in an attempt to deflect new locks while the city administration ponders their options.
Of course, this expedient has also resulted in “love locks” spreading to other (less-protected) bridges along the Seine.