The Pont des Arts (aka Love Lock Bridge) was recently in the news when a section collapsed under the weight of the locks. It's a pedestrian bridge that embodies an ancient tradition dating back to... err... 2008, where you symbolically seal your love into a lock, attach it to the bridge, and throw the key into the Seine.
The result - a bridge completely covered in locks...two bridges actually...
1. Pont des Arts - between the Louvre and the Institut de France.
2. Pont de l'Archevêché - near the south-east corner of the Notre Dame.
In true Paris style, the former is said to be for committed love, and the later for lovers.