Ridley Creek State Park encompasses over 2,606 acres of Delaware County woodlands and meadows. The gently rolling terrain of the park, bisected by Ridley Creek, is only 16 miles from center city Philadelphia.

Within the park boundaries was a small 18th century village, which grew up around the site of a mill. Now known as Sycamore Mills, the area had been previously named Bishop's Mill and Providence Mill. The miller's house, the office and library, and several small mill workers' dwellings are currently used as private residences. The park area has been designated as the "Ridley Creek State Park Historic District" on the National Register of Historic Places.

Park property was purchased in the 1960s with Project 70 funds, and developed with Land and Water Conservation Fund moneys. Park facilities were dedicated to public use in August of 1972.

The park office is in the "Hunting Hill" mansion, built by the Jeffords family in 1914. The mansion was built around a 1789 Pennsylvania stone farmhouse that forms the core of the building and serves as the reception center.