Sanmenzha is located in Sanmenzha River, from Hengxing, Sanyu Town, tongzhou bay Demonstration Zone to the south of Huanben Wangyao Port, and is a cultural relic protection unit in Nantong City.

Scope of protection: cover the whole bridge deck from east to west.

Construction control zone: It is surrounded by water or roads, so it is unnecessary to delimit the construction control zone.

Sanyu Town: Tongzhou City governs the town. 1957 was Xinyu Township, 1958 was renamed Sanyu Commune, 1983 was renamed Xiang, and 1984 was merged into Sanyu Town. Located in the northeast of the city, 30 kilometers away from the municipal government. It covers an area of 40.4 square kilometers and has a population of 38,000.