Fort de Chaudanne, Fortress in the Grette district, Besançon, France

Fort de Chaudanne is a military fortification with a pentagonal layout located in Besançon. It features a drawbridge, guardhouse, and residential quarters that originally accommodated a garrison of approximately 100 soldiers.

A redoubt known as a lunette d'Arçon was built on the hilltop from 1791 and finished in 1797, with final works between 1815 and 1830. Judged insufficient, it was replaced by the present pentagonal fort, built on the same spot between 1841 and 1845 to defend the city's south-western approaches. From 1890, and again in 1914, its artillery comprised four 90 mm Bange guns. In 1814 its garrison saw off an Austrian night attack, the attackers betrayed by their accent.

The name Chaudanne may derive from the Latin Caledenum, or from Campus Dianae, the field of Diana, after a temple the bishop Léonce reported here in the early 5th century. Dedications to Mercury and Apollo were found at the summit. The fort's name is spelled "fort Chaudane" on its pediment.

The fort is accessible by hiking trail starting from the Mazagran Bridge parking area. The path climbs steadily uphill and requires a moderate level of physical fitness to reach the site.

The fort's entrance front carries the misspelled inscription "fort Chaudane", while the barracks and the gallery leading to the cannon cellar bear the chronograms "1844" and "18 août 1842". Three sundials are set on the three faces of the barracks overlooking the courtyard.