My recollection is that the roundabouts in Paris are free for alls (a whole different kind of crazy, but it seems to work). I checked the satellite images of the circle around the arc de triomphe and it seems to be as I remember. There may be lights regulating entry into the circle, but the lanes aren't divided. And if I recall correctly pedestrians access the middle via underground walkway.

I just checked via Google street view and it confirms my memory.