Fort Popham State Historic Site

Maine’s Unfinished Civil War Fortress — Semi-Circular Granite Fort, Kennebec River Mouth, Atlantic Coast Views, Near Popham Beach in Phippsburg

Fort Popham State Historic Site is a state historic site in Phippsburg, Sagadahoc County, Maine, at the mouth of the Kennebec River. The site features an unfinished semi-circular granite coastal defense fortification begun in 1861 during the Civil War to protect the Kennebec River and the state capital Augusta — with massive granite walls, casemates, scenic views of the Kennebec River and Atlantic Ocean, fishing, picnic tables, a wheelchair-accessible shore path, and proximity to Popham Beach State Park (~2 miles).

When the Civil War erupted in 1861, Maine authorities feared Confederate naval raids up the Kennebec River toward the state capital at Augusta. Construction began on a massive semi-circular granite fort at the river’s mouth — designed to mount heavy coastal artillery in tiered casemates. But advances in military technology (rifled cannon making masonry forts obsolete) and the shifting priorities of war meant Fort Popham was never completed. Construction continued sporadically until 1869, then stopped. The partially completed structure stands as one of Maine’s most photogenic historic ruins — massive granite arches and walls overlooking the Kennebec River and the open Atlantic. Nearby Fort Baldwin (1905) was later built on the hill above.

Things to Do

Fort Exploration

• Semi-circular granite fortification
• Casemates and gun emplacements
• Massive granite arches
• Self-guided exploration

Outdoor

• Fishing — off breakwater
• Scenic views — Kennebec River + Atlantic
• Wheelchair-accessible shore path
• Picnic tables
• Photography

Park Information

Best Time to Visit

Visitor Tips

• Never finished: Fort Popham was never completed — advances in rifled cannon made masonry forts obsolete, and construction stopped in 1869.
• Triple fort day: Combine Fort Popham with Fort Baldwin (on the hill above) and Popham Beach State Park (~2 miles) for a full day.
• No restrooms: There are no restrooms at the fort — plan to use facilities at Popham Beach State Park.
• ADA path: A wheelchair-accessible shore path provides ocean views without climbing stairs.
• Photography: The massive granite arches and casemates make Fort Popham one of Maine’s most photogenic historic sites.

Frequently Asked Questions

Last updated: May 2026