Park in the car park at the foot of the castle. There are plenty of parking spaces and picnic tables.
(S/E) Walk up towards the castle and take the path on the right. Follow it until you reach a small building (Les Tavernes). You will soon come to a T-junction.
(1) Turn left twice, follow a path heading north and ignore a path on the left. Then ignore a path on the right and another on the left. Pass a small ruined building on your left and you will come to a junction before a road.
(2) Turn left (do not take the road) and follow this path, which runs almost parallel to the one you took on the way there. Ignore a turn-off on the right.
(3) Turn right onto a small path that leads to the back of the castle. Enjoy the magnificent view of the valley and walk back down to the car park (S/E).