Trail Description

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Royal Arch is perched high along a rugged fold in the Boulder Flatirons. These rocks are remnants of the Fountain Formation, a mineral-rich sand eroded from the ancestral Rocky Mountain uplift 300 million years ago. Sediments deposited by the ebb and flow of inland oceans compressed this layer into sandstone, thrust upward 45 million years ago by the same tectonic forces that created our modern Rocky Mountains. Royal Arch is a fragment of the exposed Fountain Formation sculpted by water, wind and mechanical erosion into the 20’ span we see today.

The following describes the most direct route to Royal Arch, which begins at the Chautauqua Ranger Station and climbs Bluebell Road to access the Royal Arch Trail:

Bluebell Road rises steadily over Chautauqua Park past the Mesa Trail junction (.6 miles : 6,005’) and Bluebell Shelter to the official beginning of the Royal Arch Trail (.7 miles : 6,095’). The Royal Arch Trail narrows through mixed pine to a connection for Flatiron #2 and #3 and bends south up a steep, narrow gulch (.9 miles : 6,188’). Note apple, plumb and maple in this ecologically varied riparian corridor.

The trail steepens considerably as it breaks away from the upper-gulch into a thick, cluttered forest (1.2 miles : 6,530’). It continues strenuously and without reprieve to Sentinel Pass (1.35 miles : 6,768’), a rocky notch at the top of Bluebell Canyon. Examine close-up cross-sections of the Flatiron rock formations before pressing on.

The trail drops from Sentinel pass about 100’ and resumes a demanding, twisting climb over the steady trickle of Tangen Spring to the base of Royal Arch (1.6 miles : 6,915’). Walk under Royal Arch to a set of rocky outcrops with sweeping views over the Boulder foothills, eastern plains and, on a clear, downtown Denver.

GPS Coordinates - DATUM WGS84

• N39 59.930 W105 16.970 - Chautauqua Park Trailhead

• N39 59.496 W105 17.119 - .6 miles : Mesa Trail split - keep right on Bluebell Rd

• N39 59.465 W105 17.247 - .7 miles : Begin Royal Arch Trail

• N39 59.357 W105 17.319 - .9 miles : Flatirons #2 and #3 spur

• N39 59.139 W105 17.507 - 1.2 miles : Break away from gulch, climb steepens

• N39 59.068 W105 17.489 - 1.35 miles : Sentinel Pass

• N39 58.923 W105 17.504 - 1.6 miles : Royal Arch

Worth Noting

• The Bluebell Shelter was constructed in 1921 by the local Lions Club. The stone wall, hike-in only structure is available for group picnics and activities, and accommodates up to 50 people.



• The Royal Arch Trail is a great place to observe climbers on the Flatirons.

Rules and Regulations

• All dogs must be on a hand-held leash unless they meet Voice and Sight Control Standards and display a City of Boulder Voice and Sight Tag.


• No camping or backpacking allowed. Day use only.

Directions to Trailhead

From Boulder Take Baseline Road west past 9th street and Chautauqua Park is on the left hand side. Turn left into Chautauqua Park. Overflow parking is also available along Baseline Road, south of the park entrance.

From Denver: Take I-25 North to Highway 36 towards Boulder. From Highway 36, take the Baseline Road exit and turn left. Take Baseline Road west past 9th street and Chautauqua Park is on the left hand side. Turn left into Chautauqua Park. Overflow parking is also available along Baseline Road, south of the park entrance.

Contact Information

Boulder County Parks & Open Space
5201 St. Vrain Road
Longmont, Colorado 80503
Phone: 303.678.6200
Fax: 303.678.6180
www.co.boulder.co.us/openspace