Dover Castle is a concentric castle built on a site which has been fortified since the Iron Age. The current castle was built in the 12th Century during the reign of Henry II and modifications have been made periodically until after World War II.
The keep is a square tower typical of Norman castles. Dover Keep is a nearly perfect cube and is four stories high. The original entrance was by means of a staircase and drawbridge inside the forebuilding. An entrance through the south wall was made during later renovations.
My reconstruction of Dover Keep is 30 x 30 inches (96 x 96 studs) and is about 21 inches high.
For more photos of my reconstruction of Dover Keep
For photos of the real Dover Keep and other source