This small ridge, 200m high, 30km long and 8km wide, has been a strategic point since ancient times. Caesar took on hordes of Gauls here and it was also the scene of extremely bloody combat in WWI. Eight historic sites are dotted along the route, including the famous Dragon's Lair, a cave network from which stone was extracted to build Vauclair Abbey (1134), since turned into a Museum of Remembrance, devoted to the suffering of the WWI soldiers.