Rhone-Alpes

A lot of reviewers have incorrectly placed this story in Paris, with Vincent traveling rather far to Geneva, Grenoble, etc. (His fake meeting he decribes to his wife at the beginning is near Marseille, some seven hours from Paris by freeway and therefore more likely to be a TGV train trip for business travel.)

The license plates on the vehicles are for the Departement du Rhone, so he lives in or near Lyon rather than Paris. This is a much shorter trip to Geneva although still too far to do daily, hence the need for an (fictitious) apartment in Geneva when he gets the UN "job."

The freeway bifurcation signs shown towards the middle of the movie are for the A40 southbound at Pont d'Ain, from which he can go either towards Lyon (home) or Geneva. He doesn't go home. That's probably supposed to be a clue as to his state of mind.