Denver is the capital and largest city in the U.S. state of Colorado and a county named Denver County. For this reason, Denver is the county seat of Denver County. It is at the foot of the Rocky Mountains on the South Platte River, and was founded in 1858. A nickname for Denver is The Mile High City, because Denver is very high above sea level. It is at least 5,280 feet (or 1,609 meters) above sea level at a point in the city's state capitol building. The dome at the top of the capitol building is covered in gold.