The four fortified structures of Authion

de fr

This area with its four fortifications located at high altitude was the scene of fierce fighting, both in 1793 when the French invaded the County of Nice, and in April 1945, during one of the last battles between the German army and the Allies. These stone and cement structures, bearing multiple cannon and gunshot marks, bear witness to the violence of these final confrontations.

Details

n°77728991
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  • Walking
    Activity: Walking
  • ↔
    Distance: 7.82 km
  • ◔
    Average duration: 3h 30 
  • ▲
    Difficulty: Moderate
  • ⚐
    Back to start: Yes
  • ↗
    Ascent: + 447 m
  • ↘
    Descent: - 446 m
  • ▲
    Highest point: 2,075 m
  • ▼
    Lowest point: 1,863 m
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Photos

Fortified structure at Plan Caval
Authion cattle farm
Fort des Mille Fourches
Concrete structure

Description of the walk

Park in the car park just before the "Charles Alessi" chalet in Tueis. Walk along the left side of the chalet.

(S/E) Take the GR®52. Just after the picnic tables, be careful and follow the marked path on the left, which runs along the ridge and joins a crossroads.

(1) You will now be within sight of the "La redoute des Trois Communes" fortification, known locally as "l'Authion". Follow the middle path, which passes over the ruins of the barracks.

(2) Leave the GR®52 and continue straight ahead towards the imposing structure nearby.

(3) You will arrive at the first structure, called La Redoute des Trois Communes, at an altitude of 2080 metres. The Alpine chain, the Capelets and the Cime du Diable are visible, offering a 360° panorama. Continue eastwards, following the path down towards Plan Caval. Follow the ridge line.

(4) Stay on the ridge. This second structure, Plan Caval, at an altitude of 1932 metres, is divided into three concrete sections. Below a very short path are the remains of a well-preserved blockhouse. Continue through the ruins of the barracks to find the tarmac road leading downhill, which you should follow carefully for about 100 metres . This road overlooks the Authion cattle farm.

(5) Turn right onto the track, which ends at an old turning area and a quarry.

(6) Continue off the trail and reach the bottom of the Vallon de Crep via a grassy slope. At this point, climb steeply, still off the trail between some larch trees, to reach the summit. Use the Visorando app if necessary.

(7) At this summit, you will find the Ouvrage de Mille Fourches, at an altitude of 2042 metres. It is a "Séré de Rivière" type fort dating from the late 1880s with moats. Go around the moat on the left until you reach the entrance. From there, head south towards the ruins of the barracks and go around them on the left, where you will find the track leading to the fort. Follow this track downhill to the pass.

(8) Cross the road with caution and take another track opposite, leading to the fourth and last fort, at an altitude of 2078 metres.

(9) Leave the track to see the Fort de la Forca a few metres above, identical to its twin, Mille Fourches. Follow the moat.

(10) Stop at this orientation table. Continue along the path towards the initial fork.

(1) Turn left and retrace your steps along the GR®52 until you reach the car park (S/E).

Waypoints

  1. S/E : km 0 - alt. 1,882 m - Parking at the Charles Alessi chalet - Baisse de Tueis
  2. 1 : km 1.17 - alt. 2,057 m - Carrefour de la Boucle
  3. 2 : km 1.78 - alt. 2,053 m - Trail junction
  4. 3 : km 1.93 - alt. 2,073 m - Fortified structure - Pointe des Trois Communes
  5. 4 : km 2.96 - alt. 1,927 m - Fortified structure
  6. 5 : km 3.45 - alt. 1,880 m - Road-track junction
  7. 6 : km 3.81 - alt. 1,885 m - Former turning area
  8. 7 : km 4.56 - alt. 2,040 m - Fortified structure - Mille Fourches
  9. 8 : km 5.32 - alt. 1,985 m - Col - Bévéra (rivière)
  10. 9 : km 6.19 - alt. 2,065 m - Fortified structure - La Forca
  11. 10 : km 6.31 - alt. 2,071 m - Orientation table
  12. S/E : km 7.82 - alt. 1,883 m - Parking at the Charles Alessi chalet

Notes

Hiking boots are recommended.

No water on the trail. Use the Visorando app between points (6) and (7).

Large herd of cows present. Use good reflexes, make a wide arc to get around the animals. Move slowly, do not pass between the animals, go around them on the mountain side, observe the herd and move further away if necessary. Never touch the calves or cows,move away slowly.

For safety reasons, do not enter the fortified structures.

This route passes through a protected area, which may be subject to special regulations:

Worth a visit

Always be cautious and plan ahead when you're outdoors. Visorando and the author of this route cannot be held responsible for any accidents occurring on this route.

The GR® and PR® markings are the intellectual property of the Fédération Française de Randonnée Pédestre.

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Reviews and comments

4 / 5
Based on 5 reviews
Reliability of the description
4 / 5
Ease of following the route
3.6 / 5
Route interest
4.4 / 5
bernard bb
bernard bb

Thank you, Nathalie06
You have described these historic places well
Best regards, B.

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Nathalie06
Nathalie06
• Edited:

Overall rating : 3.7 / 5

Date of your route : Oct 17, 2025
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★★☆ Good
Route interest : ★★★☆☆ Average
Very busy route : No

A pleasant hike steeped in history. Not particularly difficult, except for the section between points 6 and 7, which winds its way through the larch trees to make the relatively steep climb easier.
Very beautiful view, but a lot of fog almost all the way. Which, in itself, gives this hike another charm.

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bernard bb
bernard bb

Thank you, Christo06, for this constructive feedback
best regards, B.

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chisto06
chisto06
• Edited:

Overall rating : 4.3 / 5

Date of your route : Aug 26, 2025
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★☆ Good
Very busy route : No

Hike with stunning views of the Mercantour "Grand Capelet", "Cime du Diable" and "Mont Bego".
Clouds passed by throughout the day, offering extraordinary views.
At point 3, you can see the whole hike and the four forts.
From point 6 to point 7. To avoid a steep slope, I recommend climbing back up the valley towards point 8 and, 150 metres before this point, cutting through the woods and following the winding path towards point 7.

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bernard bb
bernard bb

Thank you Daniel, Fred and User 20378196 for your feedback
It's not always easy
These fortifications are part of our history
best regards, B

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Fred Scavo
Fred Scavo

Overall rating : 4 / 5

Date of your route : Aug 11, 2025
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★☆☆ Average
Route interest : ★★★★★ Very good
Very busy route : No

Problem between points 6 and 7: it is impossible to know that you have to climb between the larch trees, on a very steep slope with no path, somewhat "blind".
Otherwise, a very beautiful hike with peaks all around.

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danielaime06
danielaime06
• Edited:

Overall rating : 4 / 5

Date of your route : Jul 01, 2025
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★☆☆ Average
Route interest : ★★★★★ Very good
Very busy route : No

With a small group of friends, we went on this beautiful and informative hike. Everything was perfect until point 5, where the description lacked detail, but with the trail, the problem was quickly resolved.
However, the very steep uphill slope between points 6 and 7 is impossible to follow in a straight line. We had to climb "blind" by making numerous switchbacks. At the top, a herd of cows was waiting for us, which we had to go around. The rest of the hike was uneventful.
In summary, this circuit is very interesting for the fortifications you pass through and the beautiful landscapes you encounter, especially once the description between points 5 and 7 has been improved. My watch indicated an elevation gain of +- 490 m and a distance of 8.5 km.
Thank you, Bernard

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User 20378196

Overall rating : 4 / 5

Date of your route : Jul 27, 2025
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★☆☆ Average
Route interest : ★★★★★ Very good
Very busy route : No

There is a problem with the trail between points 6 and 7:
the trail heads straight up a steep, impassable slope with no path

You actually need to go from 6 to 8 via a "normal" path, then go back and forth from 8 to 7 to 9 to pick up the trail again.

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