Connecticut’s Revolutionary-Era Iron Works — Colonial Iron Furnace Ruins, Ross’ Cliffs Rock Climbing, Blue-Blazed Trail System, Half Hill Pond Views & Fishing Near Killingly
Old Furnace State Park is a historic and recreational state park in Killingly, Connecticut, near the Rhode Island border. The park features the ruins of a colonial-era iron blast furnace dating to before the American Revolution, the blue-blazed Old Furnace Trail (2–3 miles), Ross’ Cliffs with steep ledges popular for rock climbing, panoramic views of Half Hill Pond and Rhode Island, fishing, hunting, and free parking.
Old Furnace State Park preserves one of Connecticut’s most significant early industrial heritage sites — an iron blast furnace that operated from the pre-Revolutionary War era through the mid-19th century. Stone foundations, walls, and remnants of the furnace complex can still be explored along the trail. Beyond the history, the park offers the blue-blazed Old Furnace Trail, a moderate 2–3 mile hiking loop that passes through woodland terrain and ascends to Ross’ Cliffs — a dramatic series of steep rock ledges offering panoramic views of Half Hill Pond and across the border into Rhode Island. The cliffs are also a popular destination for rock climbers. Adjacent Ross Pond and Half Hill Pond provide fishing opportunities.
Things to Do
Hiking
- Old Furnace Trail: Blue-blazed, 2–3 miles, moderate difficulty
- Ross’ Cliffs: Steep ledges with panoramic views
- Views of Half Hill Pond and Rhode Island
- Woodland and cliff terrain
Historical Exploration
- Colonial iron furnace ruins: Pre-Revolutionary War through mid-1800s
- Stone foundations and walls
- Early American industrial heritage
Rock Climbing
- Ross’ Cliffs: Steep rock ledges
- Popular bouldering and top-rope destination
- Bring your own gear — no rentals
Fishing
- Half Hill Pond and Ross Pond: Shoreline fishing
- Connecticut fishing license required
Hunting
- Permitted during established seasons
- Check CT DEEP regulations
Park Information
| Feature | Details |
|---|---|
| Trail | Old Furnace Trail — 2–3 miles, blue-blazed, moderate |
| Scenic Views | Ross’ Cliffs — Half Hill Pond & Rhode Island views |
| Historical | Colonial iron furnace ruins (pre-1776) |
| Climbing | Ross’ Cliffs — bouldering, top-rope |
| Fishing | Half Hill Pond, Ross Pond |
| Camping | Not permitted |
| Restrooms | None |
| Parking | Trailhead lots near US-6 and Ross Pond — FREE |
| Pets | Leashed pets welcome |
| Admission | Free (Passport to Parks) |
Best Time to Visit
| Season | Highlights | Considerations |
|---|---|---|
| Fall (Oct–Nov) | ⭐ BEST: Fall foliage from Ross’ Cliffs; cool hiking; clear views; dry rock for climbing | Hunting season — blaze orange; shorter days |
| Spring (Apr–May) | Wildflowers; birding; green-up; pond fishing; cool weather | Muddy trails; ticks; variable weather |
| Summer (Jun–Aug) | Full trail access; long days; warm; pond fishing | Humid; mosquitoes; poison ivy near cliffs |
| Winter (Dec–Mar) | Snow hiking; solitude; bare-tree views from cliffs; ice formations | Icy cliffs dangerous; cold; short days |
Visitor Tips
- Iron furnace: The colonial blast furnace ruins are along the main trail — look for stone foundations and walls dating to before the American Revolution.
- Ross’ Cliffs: The cliff overlook provides sweeping views of Half Hill Pond and into Rhode Island — follow the blue blazes.
- Rock climbing: Bring your own gear — the cliffs are a popular climbing destination but there are no rentals or guides on-site.
- Adjacent park: Ross Pond State Park is adjacent — GPS may direct you there; follow blue trail markers for Old Furnace.
- No facilities: No restrooms or water — plan accordingly.
- Rhode Island border: The park sits near the CT-RI border — combine with a visit to nearby Rhode Island parks.
Frequently Asked Questions
Wildlife & Nature
Old Furnace SP — features the ruins of an 18th-century iron furnace. The park’s rocky terrain, hardwood forest, and stream support white-tailed deer, songbirds, and woodland salamanders.
Nearby Attractions
Killingly — adjacent. Windham County — surrounding.
What is Old Furnace State Park known for?
Old Furnace State Park in Killingly, Connecticut, is known for its colonial-era iron blast furnace ruins dating to before the American Revolution. The park also features Ross’ Cliffs, a popular rock climbing destination with panoramic views of Half Hill Pond and Rhode Island. The blue-blazed Old Furnace Trail is a moderate 2–3 mile loop through woodland terrain. The park is free to enter and offers hiking, fishing, climbing, and historical exploration near the Connecticut-Rhode Island border.
Can you rock climb at Old Furnace State Park?
Yes — Ross’ Cliffs within Old Furnace State Park are a popular rock climbing destination in eastern Connecticut. The steep ledges support bouldering and top-rope climbing. Climbers must bring their own gear as there are no rentals or guides on-site. The cliffs also offer panoramic views of Half Hill Pond. There are no restrooms, water, or facilities — visitors should come fully prepared. Parking is free near the trailhead off US Route 6.
Last updated: May 2026
More parks nearby: Ross Pond State Park is a short drive away, while Quinebaug Lake State Park lies a short drive away.
Park Location
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