Castle Rock is an affluent home rule municipality that is the county seat of Douglas County, Colorado, United States. The most populous municipality of the county, the community's population was 48,231 at the 2010 United States Census, with an estimated population of 55,747 as of 2014. It is named for the prominent, castle tower-shaped butte near the center of town. Located midway between Denver and Colorado Springs, Castle Rock is part of the Denver Metropolitan Area and the Front Range Urban Corridor.