I had a lunch in the 15th arrondissement yesterday and on my way I passed by Les Invalides and saw lot of smoke. I first thought of a giant BBQ(!), but in fact it was a demonstration. France is going through a tough economical phase at the moment and people are afraid to lose their benefits so they try to draw the government's attention! It's complicated... If you want to understand better, have a look at this excellent article (in English).