This is an active Native American sacred site, so please be respectful at all times. “The wheel was constructed by Plains Indians between 300-800 years ago, and has been used and maintained by various groups since then. The central cairn is the oldest part, with excavations showing it extends below the wheel and has been buried by wind-blown dust. It may have supported a central pole. The star alignments are most accurate for around 1200 AD, since slight changes in the Earth's orbit have caused perturbations since. The solstice alignments remain accurate today.
“The Bighorn wheel is part of a much larger complex of interrelated archeological sites that represent 7000 years of Native American adaptation to and use of the alpine landscape that surrounds Medicine Mountain. Numerous contemporary American Indian traditional use ceremonial staging areas, medicinal and ceremonial plant gathering areas, sweat lodge sites, altars offering locales and fasting (vision quest) enclosures, can be found nearby. Ethnohistoric, ethnographic, and archeological evidence demonstrates that the Medicine Wheel and the surrounding landscape constitute one of the most important and well preserved ancient Native American sacred site complexes in North America. Between 70 and 150 wheels have been identified in South Dakota, Wyoming, Montana, Alberta, and Saskatchewan” (http://solar-center.stanford.edu/AO/bighorn.html).

Please also see this site: https://www.sheridanwyoming.org/arts-culture/historic-sites/medicine-wheel/.