Fort Knox State Historic Site
Maine’s Largest Historic Fort With the Tallest Public Bridge Observatory in the World — Massive Granite Fortification Built 1844-1869 on the Penobscot River, National Historic Landmark Protecting the Penobscot River Valley, Penobscot Narrows Observatory at 420 Feet — Tallest Public Bridge Observatory in the World, Explore Gun Emplacements Magazine Rooms and Passageways of the Best-Preserved Fort in New England, Named for Major General Henry Knox America’s First Secretary of War, Seasonal Events Including Fright at the Fort Halloween Celebration, Near Prospect Waldo County Midcoast Maine
Fort Knox State Historic Site is a state historic site in Prospect, Waldo County, midcoast Maine, managed by Maine Bureau of Parks and Lands. The site features one of the best-preserved military fortifications in New England — a massive granite fort built between 1844 and 1869 to protect the Penobscot River Valley from British attack, the Penobscot Narrows Observatory at 420 feet — the tallest public bridge observatory in the world with panoramic views of the river valley and Penobscot Bay, explorable gun emplacements, magazine rooms, parade grounds, and underground passageways throughout the fort, National Historic Landmark status since 1970 and listed on the National Register of Historic Places, seasonal events including the legendary Fright at the Fort Halloween celebration, and interpretive exhibits about 19th-century military engineering and Maine’s strategic defense history.
The Penobscot Narrows Observatory is unforgettable — riding an elevator 420 feet to the top of the bridge tower rewards you with 360-degree views spanning from Penobscot Bay to Mount Katahdin on clear days. It is the only bridge observatory of its kind in the Americas.
The fort itself is a massive granite labyrinth — children and adults alike love exploring the dark passageways, spiral staircases, and underground magazines. Unlike many historic sites, Fort Knox encourages hands-on exploration rather than keeping visitors behind ropes.
Things to Do
- Observatory — 420ft bridge tower
- Fort exploration — granite passages
- Fright at Fort — Halloween event
- History — Civil War era
- Views — Penobscot Bay
- Picnicking — riverside grounds
Park Information
| Feature | Details |
|---|---|
| Location | Prospect, Waldo County, ME |
| Built | 1844-1869, NHL since 1970 |
| Observatory | 420 ft — tallest public in world |
| Named For | Maj. Gen. Henry Knox |
| Season | May-October |
| Managed By | Maine Bureau of Parks & Lands |
| Coordinates | 44.5667° N, 68.8000° W |
Frequently Asked Questions
Is Fort Knox in Maine the same as Fort Knox Kentucky?
No — Fort Knox State Historic Site in Prospect, Maine is a completely different site from Fort Knox in Kentucky. Maine’s Fort Knox is a massive granite fortification built 1844-1869 on the Penobscot River, featuring the Penobscot Narrows Observatory at 420 feet — the tallest public bridge observatory in the world. It is a National Historic Landmark and one of the best-preserved forts in New England. Open May through October.
Last updated: May 2026
