The fortress was partially dismantled in 1620 by order of Cardinal Richelieu to prevent it from being used by rebels.
Archaeological digs at the site revealed traces of occupation dating back to the 11th century.
The stones used for construction were quarried directly from the Castéou hill on which the castle stands.
During the 12th century, the castle was the center of a powerful lordship that controlled the surrounding coastal plains.
Its strategic position allowed for surveillance of maritime routes and the nearby salt production facilities.
The castle served as both a military fortification and a place of residence for the ruling nobility.
The walls show evidence of multiple renovation phases spanning several centuries of medieval conflict.
The Chateau d'Hyères, also known as the Château des Seigneurs de Fos, is a medieval fortress ruin situated on the summit of Castéou hill. Constructed between the 11th and 13th centuries, the site served as a strategic defensive stronghold for the lords of Fos. The remaining architecture includes parts of the curtain walls, towers, and a vaulted room that once functioned as the seigneurial dwelling. The site provides a panoramic view of the Hyères salt marshes, the Giens peninsula, and the Golden Islands. Excavations at the site have unearthed medieval pottery and architectural fragments that suggest a complex residential history. As of mid-2026, the site remains open to the public as an archaeological ruin maintained by the municipality of Hyères. Access is provided via a steep pedestrian path leading up from the historic old town center.
The highest point of the southern curtain wall, overlooking the salt marshes and the coastline.
Wear sturdy walking shoes with good grip, as the path is steep and the terrain within the ruins is uneven.
Carry plenty of water, as there are no facilities or vendors once you reach the summit.
Bring binoculars to take full advantage of the visibility over the islands and the coastline.
Do not attempt the hike in flip-flops or open-toed sandals; avoid visiting during high-wind warnings which occur periodically in the region.
Open year-round, but may be closed during extreme weather conditions or high wildfire risk periods common in summer.
Do not climb on the ruins or remove stones; maintain respect for an archaeological site.
