44.8256°N, 107.9209°W.
Stone circle on a limestone ridge of Medicine Mountain in the Bighorn National Forest, Big Horn County, north-central Wyoming, at an elevation of 2,940 metres. Bighorn Medicine Wheel measures approximately 25 metres in diameter and consists of a central rock cairn from which 28 stone spokes radiate outward to an enclosing rim, with six additional cairns positioned around or near the rim. Radiocarbon and dendrochronological evidence place its construction between roughly 1200 and 1700 CE, with continued ceremonial use through the historical period. Astronomer John Eddy demonstrated in 1974 that sightlines from the central cairn to specific outer cairns mark the summer solstice sunrise, summer solstice sunset, and the heliacal rising points of Aldebaran, Rigel, and Sirius in the centuries around its likely construction date. The site is sacred to the Crow, Cheyenne, Arapaho, Lakota, and Shoshone, and remains in active ceremonial use today.
Twenty-eight spokes match the days of a lunar month and the ribs of a bison, depending on which tradition is asked.