Although Arizona has three arches named Royal Arch, Colorado has only one. Located near Boulder, it has a span of 20 feet. Directions: from Chataqua Park at 9th Street and Baseline Road, hike about a half mile uphill to Bluebell shelter, where the trailhead for the arch begins. Distance to the arch from Bluebell shelter is 1.1 miles each way, with 900 feet of elevation gain. Difficulty is moderate (steep in places). Photos by Paul Reeves.