The Town of Castle Rock is a Home Rule Municipality that is the county seat of Douglas County, Colorado, United States. Castle Rock is located about 35 miles (56 km) south of Denver and 40 miles (64 km) north of Colorado Springs on the Interstate 25 corridor. It is east of the Front Range of the Rocky Mountains at an elevation of 6,210 feet. The town is the center of the burgeoning urbanization of the county. Castle Rock is named after a small prominent butte just north of the town, clearly visible from I-25. Public access is provided to climb to the top of the rock. Castle Rock is on East Plum Creek, a small stream which periodically floods. As of 2008, the city is estimated to have a total population of 44,369. Castle Rock is now the 17th most populous municipality in Colorado.