Commanderie d'Avalleur, Medieval commandry in Bar-sur-Seine, France.

Commanderie d'Avalleur is a medieval commandery on a plateau overlooking Bar-sur-Seine featuring a rectangular chapel with Gothic interior and Romanesque exterior elements. The building preserves structures from different construction periods and shows the typical layout of a Templar establishment.

The commandery was founded for the Order of the Temple around 1167 through donations by Count Manassès de Bar-sur-Seine, and is documented in cartularies from 1172. Gifts multiplied over the following decades, including Milon d'Avalleur's in 1173 and the mill of Besaces in 1174. When the Temple was dissolved in 1312 the site passed to the Order of Saint John of Jerusalem, which kept the estate under the same management; in 1520 it was joined to the commandery of Thors.

The name Avalleur, also spelled Valleur, comes from the Gaulish Aballos, meaning apple tree and also used as a personal name; the site took the name of the land and lordship. The chapel's rib vaults carry carved floral decoration, and traces of frescoes remain on some walls. On the north facade is the coat of arms of Jacques de Souvré, commander of the Order of Saint John of Jerusalem in 1616.

The site is located at Hameau d'Avalleur and is accessible from May through October on Tuesdays to Sundays. Visitors should expect a rural location outside town and wear sturdy footwear.

Of the commandery's original layout, recorded in a single plan dated 1695, only the chapel survives whole; the two towers and the sheepfold in the main dwelling were destroyed and the farm buildings reworked in the 19th century. The chapel's square fortified turret suggests it was once part of the site's defences.