Park in the small car park by the roadside just before you reach Puilaurens-Est.
(S/E) Take the right-hand branch of the path. Turn left (20 m) and step over the wire fence
(1) Walk uphill through the forest, veering slightly to the right towards the cliff visible through the trees. The first cliff is the Citadelle sector
(2) Walk along the cliff face to the left, down the slope, to reach the Hogwarts sector.
(3) Follow the route in the opposite direction to return to the car park (S/E).