En un regard
Le château en bref
Fort Saint-Sébastien was a fort designed for training the armies of Louis XIV in poliorcetics (the defense and capture of strongholds). Located in a loop of the Seine, in the alluvial plain of Achères north of the forest of Saint-Germain-en-Laye and about twenty kilometers northwest of Paris, this fort had a brief existence. Built in 1669 and significantly modified and expanded in 1670, it could accommodate between 15,000 and 20,000 men and several thousand horses. After the departure of the royal troops for war, the site was leveled as early as 1671 and reassigned to agriculture the same year. Its location is still shown on the Plan de la forêt de Laye […] and everything contained in this bend of the Seine River from Nicolas de Fer dated 1705, with the note: « Place where the fort called Saint-Sébastien was built in 1670 ».
It was rediscovered during preventive archaeological excavations in 2010 following the Seine Aval wastewater treatment plant extension project by the SIAAP. In late summer 2012, once the excavations were completed, the entire studied site was covered to allow the planned extension of the wastewater treatment plant.