Château de La Bâtie-Seyssel, Medieval castle in Barby, France

Château de La Bâtie-Seyssel is a castle perched on a rocky outcrop at the base of Mount Peney, commanding views over a bend of the Leysse river in Savoie. The fortress is entered through three successive gateways, with the first retaining its original medieval pointed-arch design.

The castle is first mentioned in the late 13th century, when Hugues de Seyssel, younger son of Humbert III, inherited the fief of La Bâtie and founded the cadet branch of Seyssel La Bâtie. The fief reverted to the senior branch in 1517 and passed by sale to François d'Oncieu in 1679; letters patent of 25 March 1699 raised it to a marquisate for Guillaume d'Oncieu. The building itself is a 13th-century fortified house restored in the 16th century.

The castle chapel, rebuilt in the 15th century, holds 4th-century Roman mosaics found at Arbin in the Gallo-Roman villa of Mérande. The Seyssel family took the name La Bâtie from this fief, and the cadet branch founded by Hugues de Seyssel in the late 13th century was known as Seyssel La Bâtie. A stone inscription in the Tour des Orgues records that Pierre de Seyssel, counsellor and chamberlain of the Duke of Savoy, built the tower in 1472.

The castle is private property and not open to visitors, so the gates, terrace and chapel can only be seen from outside. It stands on a rocky outcrop above the village of Barby, at the foot of Mont Peney, in a bend of the Leysse. Approach on foot from the village lanes; the slope up to the walls is steep and uneven.

The castle's position allowed control over an ancient Roman road that linked Savoy to Seyssel via Chambéry and the Bourget Valley. This strategic advantage made it a key point for monitoring movement through the region during medieval times.