Mill Castle

Managing agency

Routt NF — Hahns Peak/Bears Ears RD

Mill Castle is a 13.5-mile loop trail located in Colorado near the Hahns Peak/Bears Ears Ranger District within Routt National Forest. This challenging route features 4,513 feet of elevation gain, making it a demanding hike suited for experienced hikers. The loop format allows hikers to experience varied terrain and scenery throughout the journey without retracing their steps. The significant elevation gain is distributed across the route, providing multiple opportunities for climbs and descents that test endurance and leg strength. Routt National Forest offers a remote Colorado backcountry experience with alpine and subalpine environments typical of the Hahns Peak area. Hikers can expect mountain vistas, forest sections, and the natural features that define this portion of northwestern Colorado. This trail is managed by the Hahns Peak/Bears Ears Ranger District, which maintains trail conditions and provides current information about access and safety. The loop distance of 13.5 miles typically requires a full day of hiking, with total time depending on pace and terrain conditions.