Fort Baldwin is a former coastal defense fortification near the mouth of the Kennebec River in Phippsburg, Maine, United States, preserved as the Fort Baldwin State Historic Site. It was named after Jeduthan Baldwin, an engineer for the Continental Army during the American Revolution. The site was listed on the National Register of Historic Places in 1979.

Phippsburg is a town in Sagadahoc County, Maine, United States, on the west side of the mouth of the Kennebec River. The population was 2,155 at the 2020 census. It is within the Portland–South Portland–Biddeford, Maine, metropolitan statistical area. A tourist destination, Phippsburg is home to Bates-Morse Mountain Conservation Area, Fort Popham State Historic Site; it is also home to Fort Baldwin which overlooks Fort Popham, and Popham Beach State Park, as well as Pond Island National Wildlife Refuge. The town includes part of Winnegance.