North of the Hall of Union (Jiaotai dian), the Palace of Earthly Tranquility (Kunning gong) was built for the chief consort of the emperor. During Qing times, the Palace was remodeled into a Manchu-style house, which was dubbed ""pocket house” (koudai ju): the house has its main door off center to the east rather than in the middle; wooden panel doors replace lattice doors; windows open from the bottom (swinging out on hinges fastened at the top) and are propped up by sticks. Inside the Palace, along the north, the west, and the south walls are linked heated brick kang platforms. The Palace of Tranquility was at once the Shamanism sacrificial hall and the imperial bridal chamber. It still retains the original décor today.
In Qing times, the empress did not live here. It was the bridal chamber for the Kangxi (r. 1662-1722), Tongzhi (1862-1874), Guangxu (r. 1875-1908), and the abdicated Xuantong (r. 1909-1911) emperors. The couples only spent their first two days of marriage in this palace. Then they moved to live in the Palace of Heavenly Purity (Qianqing gong) or the Hall of Mental Cultivation (Yangxin dian).