The Flatirons are five dramatic slabs of ancient sandstone that tilt dramatically against the foothills, creating Boulder's iconic skyline. Formed 300 million years ago and thrust upward during the same geologic event that created the Rocky Mountains, they're visible from across the Front Range.
The Flatirons
Boulder's Defining Landmark
The Formations
The five named Flatirons are numbered 1 through 5, with the First Flatiron being the most prominent at over 1,000 feet tall. They're tilted at angles between 50 and 60 degrees, creating their distinctive slanting profile.
Hiking
Royal Arch Trail: 3.4 miles roundtrip with 1,400 feet of elevation gain. Ends at a natural stone arch with Flatiron views.
First and Second Flatiron Trail: Hikes between and around the formations. Moderate difficulty with excellent photo ops.
Chautauqua Trail: Easy 1.4-mile loop at the base. Good for families and views without major climbing.
Climbing
The Flatirons are a premier climbing destination. The First Flatiron's "Freeway" route is one of the most popular technical climbs in Colorado—a moderate Grade III with spectacular exposure.
Pro Tip: Arrive by 7am on weekends to get parking at Chautauqua. Alternatively, park downtown and take the free HOP bus or bike up. Golden hour (sunset) lights up the formations in orange and red.