Originally, the Tuan City was a small island in the Taiye Pond, belonging to the Daning Palace in the Jin Dynasty. In the Yuan Dynasty, it was called Round Island, also known as Ying Island. During the Qianlong period of the Qing Dynasty, it had undergone a large construction, and the Jade Urn Pavilion was added.

The plan of the city is circular, and the perimeter is built with city bricks. The platform is 4.6 meters high, 276 m in circumference, and 4553 ㎡ in area. There is one gate under the wall on each side of the east and west. There are two gates on the top, with Zhao Jing Gate in the east and Yan Xiang Gate in the west. People can ascended along the path with cover gates to the top of the platform. The layout of the buildings on the platform adopts a symmetrical layout, taking into account the garden. Chengguang Hall is the center of the entire platform, with the Jade Urn Pavilion to its south and Jing Ji Hall to its north, forming the central axis of the platform. The two sides are symmetrically arranged, including Gu Lai Hall, Yu Qing Zhai and the east and west houses. The Duo Yun Pavilion and the Jing Lan Pavilion are perched high on the rockery. The whole of the platform has yellow tiles and red walls. Between the ancient buildings, dozens of pines and cypresses are planted everywhere.