Strictly speaking a fortified manor more than a castle, the site at Astley Castle has been in continuous occupation since the Saxon period. As Grade II* listed, the castle is counted of national significance. Its site includes the moated castle, gateway and curtain walls, lake, church and the ghost of pleasure gardens in a picturesque landscape.
Astley Castle, Warwickshire
http://www.landmarktrust.org.uk/news-and-events/visiting-landmarks/visiting-astley-castle/