Entry No. 88 — the Durango file — filed under: outdoor
Sunnyside Mill foundation & ruins
Located in the ghost town of Eureka along the scenic Alpine Loop, the Sunnyside Mill was once a massive ore-processing facility that served Colorado's largest gold mine. After the mill permanently closed in 1939, the town was quickly abandoned, and the wooden superstructure of the mill was eventually dismantled. Today, all that remains of this industrial giant are its colossal, multi-tiered concrete foundations cascading down the red-mineral hillside.
The story
Most San Juan ghost towns leave behind a handful of splintered log cabins and rusted tin cans. Eureka leaves you a brutalist concrete staircase to nowhere. Beginning in 1873, the Sunnyside operation became a monster, chewing through complex ores of gold, silver, lead, and zinc. To process it all, miners built the massive Sunnyside Mill directly onto the steep hillside, terracing the complex so gravity could carry heavy ore down through each crushing stage.
When the mill shuttered permanently in 1939, the boom died on the spot. Eureka emptied out so fast that scavengers moved in soon after, tearing away every foot of wooden superstructure, beam, and siding for salvage. The Silverton Northern Railroad packed up its tracks, leaving only faint railroad ties decaying in the dirt along the Animas River. What was left on the hillside was stripped clean down to its gray skeleton.
What you see today cascading down the rust-red, mineral-stained slope looks less like 19th-century Colorado mining and more like the ruined foundations of a lost mountain fortress. The concrete terraces sit on public BLM land, silent proof of how fast a mountain valley can go from industrial titan to total abandonment.
What it's like
Drive northeast out of Silverton along County Road 2 (part of the Alpine Loop) until the valley opens up at the Eureka townsite. The massive gray steps are impossible to miss—they loom directly over the dirt road like giant concrete footings on the red hillside. You can park near the Animas River and walk right up toward the base of the ruins. The catch: keep your feet on solid ground. The concrete is cracked, decaying, and structurally unstable, so scrambling up the tiers is a terrible idea. Stick to ground level for sweeping photos against the San Juan peaks.
The move: Take a scenic drive along the Alpine Loop from Silverton to the Eureka townsite, where you can park and take a stroll through the historic ghost town. Photograph the dramatic, towering concrete ruins of the mill against the mountain backdrop, then enjoy a picnic near the Animas River.
📍 Before you go The ruins sit on public BLM land within the historic Eureka townsite and are free to visit, but the concrete foundations themselves are structurally unstable and should only be viewed and photographed from the safety of the ground.
- 📍 Silverton
- 💸 Free
- ⚡ Low-key
- 🌗 Outdoors
Where: Silverton, CO 81433, USA
Hours: Added 2026-07-20 — confirm current access before you go.
Pair it with
- Sunnyside Mine — Connect the dots between where the ore came out of the ground and where it was brought down the gulch to be processed at this very mill.
- Gold Prince Mill at Animas Forks - building foundation — Just a short drive further up the Alpine Loop sits another massive industrial concrete foundation from the same turn-of-the-century mining boom.
- Animas Forks Mine and Ghost Town — Continue three miles past Eureka to trade concrete industrial ruins for well-preserved wooden ghost town structures at 11,200 feet.
Good to know
How much does it cost to visit the Sunnyside Mill ruins?
It is completely free. The ruins sit on public land managed by the Bureau of Land Management (BLM).
Can you climb on the concrete foundations?
No. The concrete tiers are old, unsupported, and structurally unsound. View and photograph them safely from the ground.
How do you get to the Eureka townsite from Silverton?
Take County Road 2 (the Alpine Loop) northeast from Silverton along the Animas River for about eight miles until you reach Eureka.
Plan a visit & invite your people →
Further reading: uncovercolorado.com · westernmininghistory.com · legendsofamerica.com · sah-archipedia.org · jwdurango.com
last checked: 2026-07-20