Fort St. Philip is a historic masonry fort located on the eastern bank of the Mississippi River, about 40 miles (64 km) upriver from its mouth in Plaquemines Parish, Louisiana, just opposite Fort Jackson on the other side of the river. It formerly served as military protection of New Orleans, some 80 miles (130 km) up the river, and of the lower Mississippi River.

Plaquemines Parish is a parish located in the U.S. state of Louisiana. With a population of 23,515 at the 2020 census, the parish seat is Pointe à la Hache and the largest community is Belle Chasse. The parish was formed in 1807.