Dagukou Fort is located in the Tanggu District, where Haihe River joins the Bohai Bay, about 60 kilometers southeast of Tianjin. It is the ancient sea gateway to Beijing and Tianjin, with an important strategic significance in ocean defense. 

The fort was originally set up in the later Ming Dynasty. During the Opium War, it was expanded and five big forts and 20 smaller ones were constructed. Most of these were dismantled when the Eight-Power Allied Forces invaded China. Today, there are only three fort relics still remained, which are named as 'Wei', 'Zhen' and 'Hai'. 

Dagukou Fort was listed as an important historical site in 1988, and was opened to the public in June 1997. It is an important witness of modern China's fight against invasion.