Cañon City /ˈkænjən ˈsɪti/ is the Home Rule Municipality that is the county seat and the most populous municipality of Fremont County, Colorado, United States. The city population was 16,400 at the 2010 United States Census. Cañon City is noted for being the location of nine state and four federal prisons and penitentiaries. Cañon City straddles the easterly flowing Arkansas River and is a popular tourist destination for sightseeing, whitewater rafting, and rock climbing.