Château d'Entremont, Medieval castle ruins in Saint-Pierre-d'Entremont, France.

Château d'Entremont stands as castle ruins perched on a narrow headland at 948 meters elevation, commanding views over the deep gorges of Frou and Entremont Valley. The remaining stonework allows visitors to trace the original defensive layout of this fortress.

A motte probably stood on the knoll in the 10th century. The castle is first mentioned in 1234, when Guillaume I d'Entremont paid homage to Guigues VI of Viennois; in 1240 his son Guillaume II transferred homage to Amadeus IV of Savoy. In 1306 Rollet de Montbel broke with Savoy, and Amadeus V besieged the castle in 1307; its 300 Dauphinois defenders surrendered after a few days. The count had the castle dismantled and it served as a stone quarry.

The castle takes its name from the Entremont seigneury, though it is also called after the Teppaz hamlet where it stands, and some writers call it la Roche-Fendue. It sat on the boundary of the Entremont and Épernay parishes, and the Montbel lords who held it gave it their own name too.

A loop trail of about 6 kilometers with a steady climb crosses bridges over the Guiers and Cozon rivers on its way to the ruins. Sturdy footwear is essential as the path includes steep sections and narrow passages, particularly after wet weather.

The castle is also called château de la Roche-Fendue, a name tied to its little-known position and history. Its ruins stand at 859 metres on a knoll above the hamlet of Teppaz, overlooking the gorges of the Cozon and the Guiers Vif.