Also known as Fort Morlot and located on the south side of the plateau, it was built in 1878 by Séré de Rivières to establish military communications with the forts of the Laonnois region. An optical telegraph, using a kerosene lamp and a set of mirrors to capture and direct the sun?s rays, enabled messages to be transmitted to six surrounding forts, invisible to the enemy below. From the top of the hill, don?t miss the beautiful panorama over the lower town of Laon and the Chemin des Dames!