I assume that most visitors in Paris right now are here for the Olympics. Funnily enough, it seems like most Parisians have left as they had assumed it would be bumper-to-bumper crowded — but because they all left, Paris is actually weirdly quiet. The streets are deserted and the metro is way less busy than normal. Now is actually probably the best time to visit it because all the moaners have left and all the police/Olympics volunteers etc. are on their best behaviour because they want to make a good impression