Twin Bridge, also known as Key Bridge, is made up of Shide Bridge, a stone arch bridge, and Yongan Bridge, a stone beam bridge.

One of the holes of the Twin Bridge is square and the other is round, much like a key used in ancient times. So that is the origin of its name. Firstly built in the Wanli period during the Ming Dynasty (1573-1619),the bridge renovated in 1765, the 30th year during the reign of Qianlong (4th emperor of the Qing dynasty), and rebuilt in 1843, the 23rd year of Daoguang (7th emperor of Qing Dynasty). Shide Bridge is 16m long and 3m wide, stretching 5.9m. The length of Yongan Bridge is 13.3m, width 2.4m, span 3.5m.