Fort McKinley, Maine, Military heritage site on Great Diamond Island, Maine, United States.
Fort McKinley is a military fort on an island off Maine's coast, preserved with stone buildings, gun emplacements, and residential quarters from the 1800s. The entire complex spreads across wooded and open terrain with views of the water and surrounding islands.
The fort was built in the 1890s as part of America's coastal defense system and served for decades protecting Portland Harbor. After World War 2, it gradually lost military importance and was later abandoned.
The site is named after an American president and still shows traces of its past as a military outpost in coastal waters. Visitors can see how soldiers lived and worked in this remote position.
The fort is reachable only by ferry from Portland since it sits on an island with no bridge access. Visits are best planned during warmer months when tours and ferry service are available.
The fort was paired with a smaller military installation on a nearby island, which now functions as an environmental education center. This unexpected transformation shows how old military structures can serve new purposes.
Location: Maine
GPS coordinates: 43.67917,-70.19722
Latest update: December 10, 2025 16:30
Fort Gorges
2.6 km
Battery Steele
2.6 km
Portland Observatory
4.4 km
Maine Narrow Gauge Railroad Museum
4.3 km
Fort Preble
4.1 km
Eastern Promenade
4.1 km
Portland Breakwater Light
4 km
Harbor Defenses of Portland
4.1 km
Spring Point Ledge Light
3.7 km
Fort Levett
4 km
Abyssinian Meeting House
4.6 km
Eastern Cemetery
4.7 km
Umbrella Cover Museum
2.6 km
Tukey's Bridge
4.8 km
Wendameen
4.8 km
Ocean Gateway International Marine Passenger Terminal
4.5 km
Bagheera
4.8 km
Etz Chaim Synagogue
4.8 km
St. Lawrence Arts Center
4.2 km
Baxter Summer Home
3.1 km
Portland Pier
5 km
Mayo Street Arts
4.9 km
Eighth Maine Regiment Memorial
3 km
Payson House at Thornhurst
4.4 km
Thomas Skelton House
4.5 km
Lincoln Park
5.1 km
Mariner's Church
5.2 km
North School
4.8 kmVisited this place? Tap the stars to rate it and share your experience / photos with the community! Try now! You can cancel it anytime.
Discover hidden gems everywhere you go!
From secret cafés to breathtaking viewpoints, skip the crowded tourist spots and find places that match your style. Our app makes it easy with voice search, smart filtering, route optimization, and insider tips from travelers worldwide. Download now for the complete mobile experience.
A unique approach to discovering new places❞
— Le Figaro
All the places worth exploring❞
— France Info
A tailor-made excursion in just a few clicks❞
— 20 Minutes