A few nice Boulder, Colorado images I found:

The Sweet Lillies, at Twisted Pine
Boulder, Colorado
Image by tab2space

243/365: Mythology & Folklore
Boulder, Colorado
Image by ieure

Flatirons as seen from the Norlin Quadrangle, University of Colorado, Boulder, Colorado
Boulder, Colorado
Image by Ken Lund
The Flatirons are rock formations near Boulder, Colorado consisting of flatirons. There are five large, numbered Flatirons ranging from north to south (First through Fifth, respectively) along the east slope of Green Mountain, and the term "The Flatirons" sometimes refers to these five alone. Numerous additional named Flatirons are on the southern part of Green Mountain, Bear Peak, and among the surrounding foothills.

The Flatirons were known as the "Chautauqua Slabs" circa 1900 and "The Crags" circa 1906. There are two hypotheses regarding the origin of the current name, one based on resemblance to old-fashioned irons, the other based on resemblance to the Flatiron Building completed in 1902.

Images of the numbered Flatirons on Green Mountain are ubiquitous symbols of the city of Boulder. The area abounds with Flatirons photographs, drawings, paintings, and sculptures. The city government, the University of Colorado, and many businesses make use of this symbol in their logos, advertisements, and marketing materials. Many businesses also use the word Flatirons or Flatiron in their names. In addition, Boulder often is referred to in the tech industry as the "Silicon Flatirons", analogous to Santa Clara Valley’s famous nickname.