Castlewood Canyon State Park, State park in Franktown, Colorado, US.

Castlewood Canyon State Park covers 2,136 acres at 6,200 to 6,600 feet on the northern edge of the Black Forest, where the Palmer Divide brings extra moisture. The canyon exposes caprock ledges above grasslands, shrublands, riparian strips and foothills conifer stands. A trail sign on a wooden post points left to Creek Bottom Trail and right to Rim Rock Trail.

Castlewood Canyon State Park was formed in 1964 after an 87-acre purchase in 1961 and a further 792-acre purchase in the late 1970s. The Castlewood Dam, built in 1890, collapsed at 1 a.m. on 3 August 1933, sending a 15-foot wall of water down Cherry Creek to Denver, 15 miles away; two people died. About a third of the dam remains on the west bank, while the roughly 100-metre eastern section was washed away.

The park takes its name from Castlewood Canyon, where Cherry Creek cuts through the Black Forest. The Cherry Creek Rockshelter archaeological site lies within the park boundaries, and the canyon's caprock ledges draw rock climbers. Picnic areas can be reserved for groups.

The grounds offer a network of trails of varying length and difficulty plus areas for outdoor activities like climbing. Visitors should prepare for changeable weather and wear comfortable shoes for hiking.

The site hosts five different ecosystem types that exist closely packed together in the same landscape. This tight clustering of diverse habitats makes it a living laboratory for nature observers.