as stated in this blog, there was a mentioning of a survival mode map called "Paris". This interview is part of Gamescom 2011 MW3 survival preview:
We got to play on the Paris map, which was a medium-sized chunk of urban devastation where alleyways, bridges, and demolished houses made for some interesting routes throughout the map. Of course, you don't have to go anywhere--you just have to survive. The twist, as you might have guessed, is that the waves of enemies ramp up in difficulty and sheer ridiculousness the longer you survive. While you start against a small handful of on-foot soldiers, you eventually have to deal with attack dogs strapped with C4, heavily armored juggernauts, and even attack choppers.