Park in the car park at Karl Marx Park in Fontaine (a suburb of Grenoble).
(S/E) Set off from the car park heading towards Château Borel, a vast Dauphiné mansion. Go round it on the right. When the tarmac ends, you’ll spot a path continuing straight ahead. Very quickly, it begins to climb steeply. It branches off at times.
You’ll reach a slight plateau from which you’ll have a 180° view of the Grenoble basin at a place called La Balme du Glos.
(1) Continue along this path. It leads onto a small tarmac road, the Chemin des Bois des Vouillants.
(2) Turn left onto it. The path descends very steeply and winds twice before reaching the valley. When you reach Rue de la Résistance, turn left.
Very soon, turn left again to re-enter Karl Marx Park. Walk past the tennis courts before reaching the château and the car park. (S/E)