Pillar tombs are monumental graves, which typically feature a single, prominent pillar or column, often made of stone. A number of world cultures incorporated pillars into tomb structures. In the ancient Greek colony of Lycia in Anatolia, one of these edifices is located at the tomb of Xanthos. In the town of Hannassa in southern Somalia, ruins of houses with archways and courtyards have also been found along with other pillar tombs, including a rare octagonal tomb.