Entry No. 173 — the Denver file — filed under: outdoor

Rattlesnake Gulch Trail

Eldorado Canyon is famous for its sandstone walls and the climbers dangling off them — so almost everyone clusters at the bottom and looks up. Cross the creek and start climbing instead, and within a mile you reach a quiet hillside scattered with brick footings and a stone retaining wall: all that's left of the Crags Hotel, a luxury resort reached by inclined railway that opened in 1908 and burned in 1912. Switchback higher and the trail delivers a Continental Divide overlook where the eastern plains spill out one way and snow-streaked peaks rise the other. Ruins, railroad-grade history, and a big-sky payoff, on a loop most canyon visitors never bother to find.

The move: Make the climb the date: pack water and one good snack, then hike up together past the burned-out Crags Hotel ruins, reading the interpretive signs aloud and imagining guests arriving by railcar in 1909. Keep going to the Continental Divide overlook, claim the bench, and trade which view you'd rather wake up to — plains or peaks — before looping back down through the canyon.

📍 Before you go A 3.8-mile lollipop loop with about 960 ft of gain, rated moderate — a steady grade on rocky, gravelly trail, no scrambling. The trailhead sits roughly 0.6 mi inside Eldorado Canyon State Park off Eldorado Springs Drive (Route 170); from Denver it's about 45 minutes via US-36 and Route 170 through Eldorado Springs, or about 20 minutes south of Boulder. Best from late spring through fall; the upper switchbacks and overlook hold snow and ice into spring and after storms, so bring traction in shoulder season and start early to dodge summer afternoon lightning at altitude (trail tops out around 7,200 ft). This is a fee state park requiring a valid Colorado Parks pass or daily vehicle entrance fee, and — critically — on weekends and summer holidays in the warm season the park requires a timed-entry vehicle reservation booked in advance; on those days you can instead skip the car and ride the free Eldo Shuttle from Boulder. Parking is limited and fills fast. Leashed dogs are allowed, and the lower trail is open to mountain bikes. You'll find the Crags Hotel ruins (brick foundations and stone walls), a Continental Divide overlook with benches, and views down into the canyon and out to the plains.

• 📍 Eldorado Canyon State Park (Eldorado Springs, ~20 min south of Boulder)
• 💸 Free
• ⚡ Up for anything
• 🌗 Outdoors

Where: Rattlesnake Gulch trailhead, on the south side of the road roughly 0.6 mi past the entrance station in Eldorado Canyon State Park, off Eldorado Springs Drive (Route 170), Eldorado Springs / Boulder, CO 80025. From Denver: US-36 toward Boulder, exit at McCaslin Blvd and head south/west via Marshall Rd to Route 170, then west through Eldorado Springs to the park entrance (about 45 min). From Boulder: south on Route 93, right on Route 170 and into the canyon (about 20 min).

Hours: Day-use, free. Best season: Late spring through fall (summer and fall are ideal). Confirm trail & road conditions before you go.

⚠ Seasonal or scheduled — always check before you go.

Plan a visit & invite your people →

Proof: source 1 · source 2 · source 3 · source 4

last checked: 2026-06-10