The Fort de Châtillon was a fortification located about south of Paris in the communes of Châtillon-sous-Bagneux and Fontenay-aux-Roses. It was built in 1874 and was razed beginning in 1957, making way for expansion of the French nuclear research facility at Fontenay-aux-Roses. The fort is named for the town it was designed to protect, Châtillon-sous-Bagneux, but the greater portion of the site is actually within Fontenay-aux-Roses. The main entry and the portions in Châtillon were destroyed at the end of the Second World War.