Tour and climb the Gros Cerveau of Ollioules

Description

Start near the treatment plant, in the car park of the astronomical observation site in the city of Ollioules and a large sports course. Park in the unsurfaced car park on left of the trail (S).

Directly after the car park entrance, heading south by the sports track, find a simple red and white gate that opens on the Bonnet valley.
Take the blue-marked path down into the valley towards the west.
The trail overlooks the Esquières left and leads to a fork above a place called Le Lançon (1). Turn right on the steep footpath (still marked in blue), which begins its progress through the wood in wide loops until you arrive at the D20 (2).
Turn left and continue on this paved road for a few hundred metres to reach the enclosed path with a green fence on the right leading to the fort (1,300 m) (3).
Even if you are tempted to quickly reach the fort, do not take this path to the right (it is quite long and uninteresting) but continue on the paved road to the tank at the base of the cliff (4).
The arrival at the fort is then done with a much better view than by the direct route.
It overlooks the of Jaume or Val d’Arren quarry, framed by the Gros Cerveau in the south and the Barrière de la Jaume to the north. The view covers almost 270° and is already dazzling! In the background it is even possible to be lucky enough to see Sainte Beaume massif with characteristics buttresses.
Turn right and take the edge of the cliff to the north along the trail marked in not only blue, but also red and white because it is a part of the GR51. Progress through beautiful karst formations, limestone rocks and pebbles rolled by erosion due to runoff from the summit where a first orientation table which faces inland. But we also come upon breathtaking views of the coastline.
Shortly thereafter, enter the site of the fortified structure of the Gros Cerveau. At the fork (5), a small bridge is located on the left of the path and a small cave, identified as a "military area" and the GR51 which skirts the fort to the North (and also allows entry to it). Rather continue straight south along the west boundary wall, which runs past the entrance to the walled part of the premises including soldiers’ residences. These are not open to the public, although they are partly in ruins. On the right side you can see the sea flush part of a blockhouse. Continue to follow the city wall until you reach a second orientation table in the extreme south of the plateau, facing the sea (6).
Here we have a unique view on the coast of La Ciotat in Porquerolles. Its location slightly behind Le Faron and quite far from the city of Toulon adds a wilder tone, more Provencal, than at the summit of its neighbouring brother Le Faron.

After the orientation table, turn back on yourself and aim for the square watchtower flanked along the angle of the wall. Then turn right on small path uphill, barred with a blue cross and then easily reach the bottom of the east ditch (natural moat that completely replaces the south and the east ditches/ramparts found elsewhere) .
Cross the gap and reach the inside of the the fort (by heading past a modest little drop of 3.5 m using your hands, great for the kids and absolutely safe!).
“Alternative route: for less skilled or more fearful hikers, you have to head round the fort by the north, from WP (5). ''
We can then continue on into the fort.
Finally, reach the end of the plateau to the north-east, not far from the altitude marker.
' Note: due to a large amount of information at the top, the IGN 1/25000 is not very legible, whereas on Visorando, a zoomed-in version of a Geoportail-ign map shows a circular interior path in the tower at the fort, letting walkers reach the altitude signpost and the beginning of the descent, turning anti-clockwise from the 2nd orientation table. See in the photos in an enlarged view of the area on Google Maps.”

Here, join the GR51 (7), which descends rapidly, avoiding the early loops of the road.
After this last part, turn left at hill 311 (8), leaving the road and the GR51 (to limit the time on the road and make the most of the Mediterranean pine forest) to take a path on the left behind the big green tagged tank. Then we walk to the edge of the cliff overlooking the quarry, north of hill 352.

The trail narrows sharply. At the first intersection (9), turn left over a few dozen metres, then - take care! - quickly turn right after a small cairn on a narrow trail through the scrub. This trail meanders down and rejoins the loop in the road below.
If you miss this path, do not panic, other trails criss-cross these places. The cars on the road below can be heard very well, which can also guide you!

Continue to the left until (10) hill 285 and turn left following the GR51 (red/white markings), which continues on a small portion of paved road (behind the Société du Canal de Provence barrier). Before reaching the Hugueneuve tank behind its wire fence, turn left into the wood (red/white markings) on the path down to the rear of the treatment plant. Head around and come to the starting point in the car park.