By train:
You can reach the center of Paris, Châtelet station in just 30 minutes by RER, and 13 minutes from the Cité Universitaire. You can get to Bagneux by taking RER B to Arcueil Cachan station and walking 10 minutes. Also, you can go to Porte d'Orléans and take bus 197 to the Carnot - Aristide stop.