《晋书·帝纪·第九章》
太元二十一年正月，建清暑殿。三月，慕容垂攻下平城。四月，新建永安宫。
夏四月，新作永安宫。
In the first lunar month of the twenty-first year of Taiyuan, the Qingshu Hall was built. In March, Murong Chui captured Pingcheng. In April, the Yong'an Palace was newly built.