Doing some quick research, it seems it is. I wonder how they measure it, though, because it's dimensions aren't the largest. Notre Dame de Paris' fame, though, I'd imagine, comes more from it's age (one of the first Gothic-styled churches, ever) location (on the island where Paris originated), and the fact that it's still the Diocese of Paris' cathedral (main/headquarters) church.
Not to hijack the thread, but my favorite church of Paris lies just a few blocks away also on the Île de la Cité (City Island) is the La Sainte-Chapelle (The Holy Chapel):
