Château de l'Étenduère, Ruined castle in Les Herbiers, France.

Château de l'Étenduère is a ruined castle in Les Herbiers, Vendée, of which only fragile wall sections and several tall square chimney stacks remain, built of pale grey masonry with open window openings and missing roofs. Dense ivy climbs the walls and stacks. The tallest standing sections are on the left, with the wall continuing to the right, partly hidden by leafless bushes at its base.

The site is recorded as a simple lodging in 1375 and as a noble hôtel in 1484. In 1622 it was fortified with cannon ports, a drawbridge and machicolations. It was burned during the Wars of the Vendée, leaving only a few fragile wall sections. The family of the Herbiers, marquis de l'Estenduère, traced its origins to the 11th century; Henri-François des Herbiers commanded the French navy at the 1747 Battle of Cape Finisterre.

The château gave its name to the Maison des Herbiers, marquis de l'Estenduère, a Poitou and Aunis noble family documented since the 11th century. Its best-known member, Henri-François des Herbiers, commanded the French fleet at the battle of Cape Finisterre in 1747. Volunteers of the association Passion Patrimoine have worked on the ruins since 2016.

The vestiges stand southwest of Les Herbiers, near the Buzinière area, and are reached on foot. The masonry is fragile and the ground uneven, so wear sturdy shoes and keep to the outside of the walls. The site is an open ruin with no facilities; the volunteer association Passion Patrimoine has worked on it since 2016.

The site gained official recognition in 2019 when selected by the Mission d'Identification du Patrimoine Immobilier en Péril as endangered heritage requiring protection. A local association called Passion Patrimoine has been conducting hands-on preservation work since 2016 to prevent continued deterioration.