From Luxembourg, take a train towards
Saint-Remy-les-Chevreuse (beware: not all trains go there).
Get off the train at Bures-sur-Yvette station. Follow Boulevard Georges Seneuze (next to the railway). About 500m from the station, take the first street on your right (at the "Rondpoint du 8 mai 1945" roundabout). The entrance to IHES is on your right (big green gate). The address is: 35 route de Chartres.
The program starts at 9:00. The travel time is 40 minutes, trains leave every 12 minutes. We recommend that you aim to catch at the latest the 8:11 from Luxembourg, arriving 8:54.. There are frequent delays on this line, and the timing can be quite erratic.
You can get a ticket at the main Luxembourg station. Beware that machines may not accept foreign credit cards, and there may be a queue at the ticket booth.
The same RER B line also goes to Roissy Charles de Gaulle airport, as well as to Gare du Nord (Eurostar). More information on transportation at the RATP site.
Maps: IHES, Hotel de Senlis, Hotel des Jardins du Luxembourg, Hotel Andre Latin, Hotel Acte V, Hotel l'Apostrophe.