《北齐书·本纪·卷四》
十二月庚申，皇帝向北巡视到达速岭，观察山川的险要地方，将要修起长城。
十二月庚申，帝北巡至达速岭，览山川险要，将起长城。
On Gengshen, December, the emperor made an expedition north and arrived at Sule Ridge, viewing the dangerous peaks of the mountains, intending to build the Great Wall.