Building Marc de Hemptinne
Chemin du Cyclotron, 2
The "Marc de Hemptinne" building, also known as "Cyclotron", is located at coordinates F8-F9 (building 1) on the Louvain-la-Neuve map below.
From the E411 motorway, take exit 8a, then the third exit of the roundabout (left direction), then first on the right : "Boulevard Baudouin Ier". Pass in front of the gas station (Q8), and use the P3 carpark or "Parking Baudouin Ier" (free) on the left at the roundabout (F8) (do not use the P1 carpark, which requires a UCL special label).
By train, walking directions
The "Louvain-la-Neuve Université" train station, not to be confused with "Louvain" train station, which is in a different city, is located at coordinates D6-D7 (building 18 labelled "SNCB" on the Louvain-la-Neuve map below). The IRMP institute, located at the building "Marc de Hemptinne", is 10 minutes on foot from the train station.
When you get out of the station, you are on the "Rue des Wallons" street. Walk to your left (having the train station main entrance behind you); this is also the uphill direction of the street. Climb up this street which zigzags a bit. You will first find the "Place des Wallons" square and then after yet another zigzag on the right you will arrive at the "Place des Sciences", a big square with a wooden floor in the middle. Continue walking across the square and pass between a large concrete building with a trapezoidal facade (the "Bibliothèque des Sciences", i.e. the Science Library corresponding to building 7 on the Louvain-la-Neuve map below) and an octogonal building named "Salmigondis" (building 28a on the Louvain-la-Neuve map below). Turn to the right and you will arrive at a parking lot. Take slightly to the left and you should see behind the trees a high grey tower or chimney (indicated with a little blue square on the Louvain-la-Neuve map below). Cross the parking lot reaching this chimney and you will be on a pedestrian path called "Chemin du Cyclotron"; the path passes right besides this chimney. Take the path on your right. After a few tens of meters the path tunnels under the motorway ("Boulevard Baudouin Premier"). Walk through the tunnel and, after exiting it, the first building on your right is the Marc de Hemptinne building where the IRMP institute is located.
As a matter of fact, GPS or computer-maps do not precisely locate "Chemin du Cyclotron, 2". Look, in the Maps section below, at the exact location of the institute.