Ninemile Canyon (also Nine Mile Canyon) is a canyon, approximately 40 miles (64 km) long, located in Carbon and Duchesne counties in eastern Utah, United States. Promoted as "the world’s longest art gallery", the canyon is known for its extensive rock art, most of it created by the Fremont culture and the Ute people.
The rock art, shelters, and granaries left behind by the Fremont make Ninemile Canyon a destination for archaeologists and tourists alike.
There are at least an estimated 1,000 rock art sites in the canyon, with more than 10,000 individual images.
The true figures may be ten times as high, but there is no question that rock art is more concentrated here than anywhere else in North America. Much is in the form of pecked petroglyphs, and there are many painted pictographs as well.
Researchers have also identified hundreds of pit-houses, rock shelters, and granaries, although only a limited amount of excavation has been carried out. Many of these structures are located high above the canyon floor on cliff ledges, pinnacles, and mesas.
According to en.wikipedia