IPhT is located 20km south-west of Paris, in a place called Orme des Merisiers (see map).
Institut de Physique Théorique
Phone number and email address
direction/administration : +33 (0)1 69 08 73 85
From Paris or Charles-de-Gaulle airport (or Orly airport via Orlyval and Antony station), take the train RER B direction Saint-Remy-les-Chevreuse. Take the train to Le Guichet (approx. 35' from Paris, 1:15' from Charles de Gaulle, make sure your train stops there). Off at Le Guichet, take the pedestrian underpass at the front of the train. Turn right after the café and cross the street. A pedestrian way on the left leads to the bus station. Bus 9 (the default bus at this station) leaves every 5' at rush hours (every 15' off peak), and reaches Orme des Merisiers in 8'.
A second option (usually slower by 5' to 10') is to get off at Massy-Palaiseau (approx. 25' from Paris, 1:05' from Charles-de-Gaulle) and take bus 91.06 or 91.10 which reach Orme des Merisiers in 22'.
Unless you have a weekly or monthly "navigo" pass, you will need two separate tickets for the train and bus. Both can be purchased from vending machines, and they are 20% cheaper if you buy 10 at a time. The bus tickets are referred to as t++ tickets. The apps "ratp" and "transdev" provide real-time information on trains and buses.
Entering the Site:
Exit the bus at Orme des Merisiers. There is a gate for pedestrian access right in front of the bus stop. After the gate, go right. Once you reach the road, go left. IPhT is building 774 at the end of the road on the right side (approx. 10 minute walk from the bus stop).
If you have a valid CEA badge, there are direct, free shuttles from Paris (porte d'Orléans bus station) to Orme des Merisiers. Departures at 7:15, 7:35, 7:45, 7:55, 8:00, 8:10, 8:20, 8:30, 8:40, 8:50, 9:00, 9:15
Check for updates (esp. during summer)
and/or download the "zenbus" app, which has real time information.
In addition, there are many free buses operated by CEA, that can take you from/to many other places in the area, but only once a day, and through the main center of Saclay. You will reach IPhT around 9:00am and leave at 4:30pm. Ask our administrative staff for details.
Determine the best route via your preferred app. Our Institute is referenced as IPhT Saclay on google maps.
You can reach IPhT directly by walking from the train stations of La Hacquinière or Gif-sur-Yvette on RER B. This requires both a valid access badge to Saclay and a good knowledge of the neighborhood. But the gate beside the swivel is generally open during the business hours.
It is not a valid option on your first visit. The walk includes a steep forest path uphill, which can be very muddy, thus take good shoes. It takes about 30 minutes for an experienced hiker to reach IPhT from La Hacquinière (see map).