《新唐书·列传·卷二十五》
太宗巡视洛阳，命令阎立德按照明亮干燥的要求建造行宫以便避暑，于是在汝州西边的山上测量地基，临近汝水，斜对广成泽，名叫襄城宫，征用劳役共一百多万人。
太宗幸洛阳，诏立德按爽垲建离宫清暑，乃度地汝州西山，控汝水，睨广成泽，号襄城宫，役凡百余万。
When Emperor Taizong inspected Luoyang, he ordered Yan Liben to build a summer palace that was sunny and dry to escape the heat, so he surveyed the land on the mountain west of Ruzhou, which was adjacent to the Rushui River and obliquely facing the Guangcheng Marsh, and named it Xiangcheng Palace. More than 1 million laborers were mobilized for the project.