44.5903°N, 104.7153°W.
Igneous monolith rising 265 metres above the Belle Fourche River in Crook County, northeastern Wyoming, at the eastern edge of the Black Hills uplift. Devils Tower (Bear Lodge) is composed of phonolite porphyry that intruded the surrounding sedimentary rock approximately 50 million years ago in the Eocene, then was progressively exposed by erosion of the softer surrounding strata; its near-vertical columnar jointing produced the distinctive hexagonal and pentagonal column faces. More than two dozen Native nations including the Lakota, Cheyenne, Kiowa, Crow, and Arapaho hold the formation sacred, with the Lakota name Mato Tipila ("Bear Lodge") and a widely shared origin narrative involving girls pursued by an enormous bear. President Theodore Roosevelt formally designated it the first United States National Monument in September 1906 under the Antiquities Act. The first recorded ascent was by local ranchers Bill Rogers and Willard Ripley on July 4, 1893, using a ladder of wooden pegs hammered into a single vertical crack.
The original peg-ladder fragments are still embedded in the rock face today.