The Fort de Châtillon was a fortification located about 5 kilometres (3.1 mi) 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 was 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.