Jean de Bourbon Chapel was erected at the end of the 15th century on the southern arm of the small transept of the Ecclesia Major of Cluny III. Although built in Flamboyant Gothic style with ribbed vaults, tall windows, niches, and sculpted culs-de-lampe, it retains a polychrome Romanesque arcade above the portal. Explored by the American archeologist Kenneth John Conant in 1931, it was the subject of new excavations in 2020. The operations allowed finding the foundations of the 12th-century Saint-Eutrope chapel as well as a sarcophagus with bones.