photographs and the Gentieu collection of Brandywine River Valley images at Hagley Museum and Library contain approximately 400 images of this area between 1883 and 1936. Industrial buildings and structures on the National Register of Historic Places in Delaware Historic American Buildings Survey in Delaware 1802 establishments in Delaware Du Pont family residences Historic Mechanical Engineering Landmarks National Historic Landmarks in Delaware Buildings and structures in New Castle County, Delaware 1921 disestablishments in Delaware Gunpowder mills National Register of Historic Places in New Castle County, Delaware