Chautauqua Park sits at the base of the Flatirons on the western edge of Boulder, where the city's residential streets end and the mountain begins with little warning. The park is the main gateway to Boulder's 45,000-acre Open Space and Mountain Parks system, and the trailhead parking lot fills early on weekends.
The Flatirons — three enormous slabs of red Fountain Formation sandstone tilted at about 60 degrees — are one of the most distinctive geological formations in the Colorado Front Range. The Flat Iron Trail (also called First Flatiron Trail) is a moderate 3-mile round trip with views of the whole Boulder valley; the Royal Arch Trail is more demanding but rewards with one of the most photographed natural arches in Colorado. Experienced rock climbers come from across the country to climb the Flatiron faces. For a gentler outing, the Chautauqua Meadow loop is a paved path through the Victorian campus and the meadow beneath the first Flatiron.
The Chautauqua Dining Hall, a 1898 Victorian building at the trailhead, serves breakfast and lunch and is worth a stop before or after hiking. The auditorium hosts summer concerts and films.