Cair Andros was a Stronghold inhabited by the Dunedains,presumably their last, Before they were slaughtered there during the Calamity.Assassins Wolf Huntic and GunxShinobi later discovered it in the Early days of the Assassin Guild, And used it as a dungeon were prisoners were kept. Unfortunately the entrance to the Stronghold collapsed, Leaving those not able to escape stuck. Rumour has it that there are still prisoners stuck in the ruins,With no way out.
The Dunedains were a hybrid between Elf and Man, Because of their elf ancestry they lived longer ,but lacked the physical strenght of normal humans.They were often shunned by both races because of their combined blood. Forced to hide from their Elven and Human ancestors they build numerous Strongholds and developed a whole society living underground. They were eventually slaughtered during the Calamity.But research from Wolf and Gun shows that there still should be a small group alive, Today.