Zhenhai Bridge, also known as Tunxi Bridge, commonly known as Old Bridge, runs through Laojie and Liyang from east to west and is the gateway of Tunxi. Zhenhai Bridge is a 7-hole stone arch bridge with 6 piers, with a length of133m, approach bridges at both ends of15m, a width of 6m and a height of10m. The arch span is13m or15m. The pier is built into an isosceles triangle, and the water stone at the top of the pier is inclined. The arch foot and the arch ring are interlaced with brown kenaf strips. The stone is cemented with glutinous rice, kiwi fruit, rattan juice and mortar. There is a word "no fish" in the hole in the middle.