Château des Adhémar, Medieval castle in Montélimar, France.

Château des Adhémar is a castle on a hill in central Montélimar. Its surviving Romanesque palace, the logis seigneurial, has a lower hall with a French ceiling and an upper hall of 125 m² whose west side opens through a row of nine semicircular arches with carved columns onto a loggia. The keep has three floors, and the Narbonne tower stands outside the first wall to the north.

The first castle was an 11th-century motte built by the Count of Toulouse above the parish church of Saint-Pierre. In the second half of the 12th century the Adhémar family turned it into a palace, their sovereignty recognised by an imperial diploma in 1164. Around 1200 two brothers divided the lordship, creating a northern pole with the Tour de Narbonne and an eastern citadel. The popes held the castle until 1447, and in 1580 Lesdiguières had it dismantled except the keep.

The name Sainte-Guitte given to the castle chapel comes from a 19th-century misreading of the archives. In the 16th century the nave of the 11th-century church was turned into a gunpowder store, while the northern part remained a chapel dedicated to Saint Agatha. The seigneurial residence is a rare surviving palatial ensemble in Romanesque architecture, with a lower hall and an upper hall of 125 m² opening west through a row of large semicircular windows onto a loggia facing the town.

The castle opens Tuesday through Sunday with seasonal hours that vary throughout the year, so checking ahead is helpful. The climb to the walls and upper areas requires some physical effort, making comfortable footwear important for exploring the site.

From 2000 to 2017, the castle served as a contemporary art center, regularly hosting rotating exhibitions of modern work. This unusual function brought together contrasting worlds, showing how historical spaces can take on new creative roles.