Auburn Valley State Park

Auburn Valley State Park (formerly Auburn Heights Preserve) is a 471-acre (191 ha) public recreation and historic preservation area located in Yorklyn, Delaware, United States. The state park preserves the former home and estate of the Marshall family as well as portions of the family's former mills alongside the Red Clay Creek and additional land purchased by the state. The preserve contains 4 miles (6.4 km) of trails for walking and biking, including a 1.2 mile paved loop. The state owns conservation easements on 160 acres of privately owned land adjacent to the park to help maintain the park's rural character.

The park also features a large collection of operational steam cars and a miniature coal-powered train that runs on tracks encircling the estate. The mansion, mills, and steam museum were added to the National Register of Historic Places in 1980 as the Auburn Mills Historic District.