From Charles de Gaulle airport (CDG) or from Paris, join the line B of the "Reseau Express Regionnal", RER B, in blue on the RER map. Take the direction of St Remy les Chevreuse, and get off at Orsay-Ville. Then, take the underpass that goes under the railtracks (see photo) and take a little street on the left ("Rue Georges Clemenceau" - see photo), parrallel to the railtracks, which leads to IPN. IPN is building number 100, which is the first one you will find on your right down "Rue Georges Clemenceau" (it's about 5min walk from the RER station).
- Paris subway map
- Orsay campus map : IPN is building 100 (noted 100A and 100M in the map)