This is the Arc de Triomphe du Caroussel - not that "other Arc".
When you mention that you saw "the Arc" in Paris, everyone knows you are referring to the Arc de Triomphe, which sits at the end of the Champs-Elysees and is rather famous as the French monument to those who fought and died for France. But that one is actually called the Arc de Triomphe de l'Etoile. You can see why it's just called the Arc. That's a mouthful.
But this one is actually different, and smaller (by about half), and located elsewhere in Paris. This one is called the Arc de Triomphe du Carrousel, and is situated just outside The Louvre. Despite it's lack of stature in comparison to it's "big brother", it's still awesome and worth seeing. Size doesn't really matter, after all.
I was at The Louvre shooting a wonderful sunset in the front courtyard, and generally just enjoying the fact that I was in Paris. The Louvre! The Eiffel Tower! Sunset! Photography! I was pretty fired up, and still get excited thinking about it.
Anyways, I saw this arch (I'm going with the American word here) and loved the light and shadow play, so I set up and despite all the tourists, went ahead and fired away. They were moving so slow that it was obvious I could never wait them out.