Montagne de Dun, Mountain summit in the Brionnais, Saône-et-Loire, France

Montagne de Dun is a summit in the Brionnais, on the commune of Saint-Racho in Saône-et-Loire, reaching 736 metres and overlooking the Sornin valley. Its highest point, called Dunet, rises slightly to the east at 732 metres, while the main summit at 721 metres holds two orientation tables. The slopes are steep and difficult to climb.

Dun was the seat of the viscounty of Mâcon until the 12th century, held by the Le Blanc family. In 1180 Philippe Auguste besieged the fortress and took it; the walls were razed and only the church was spared, because "the King of France does not destroy the house of the King of Heaven".

The name Dun comes from a Celtic root meaning "citadel, fortress, fortified enclosure", later "hill, mount". The mountain gave its name to villages such as Anglure-sous-Dun, Mussy-sous-Dun and La Chapelle-sous-Dun; Chauffailles was called Saint-André-sous-Dun until 1254, when a large fire led to its new name. In 1580 Dun was still a pilgrimage site, climbed on 29 June for Saints Peter and Paul and on 9 October for Saint Denis.

The summit plateau, at 721 m, holds two orientation tables, one facing La Clayette and one facing Chauffailles, from which more than 25 bell towers can be seen. The true high point, Dunet, lies slightly east at 732 m. The climb is steep, so plan for the gradient and carry water.

The summit's orientation tables, one facing La Clayette and one facing Chauffailles, reveal more than 25 bell towers. The true high point, called Dunet, lies slightly east at 732 metres, while the marked summit is 721 metres. The name Dun comes from a Celtic root meaning citadel or fortified enclosure.