Be careful when travelling around La Defense
I would tell people who plan to visit La Défense to realise that the underground ticket when traveling from Paris since the Défense area despite its proximity to the Arc de Triomphe belongs to the Metro zone 3 which means that the ticket is more expensive than that of the zone 1 of Paris. Do not try to cheat the monitoring station there is tight control of passage, if you have paid the wrong amount there is a fine of 30 euros per person and you will not receive kind treatment. Thanks!