The Flatirons are a series of iconic rock formations located in Boulder, Colorado. They are known for their distinctive flat, slanted shapes and rise dramatically from the surrounding landscape. The formations are part of the Foothills of the Rocky Mountains and are popular among hikers, climbers, and photographers. These geological features are primarily composed of sandstone and were formed millions of years ago through a combination of erosion and tectonic activity. The Flatirons are easily accessible from various trails in Chautauqua Park, making them a favorite destination for outdoor enthusiasts and nature lovers.