Norman castles, which proliferated across England after 1066, were defined by several distinct architectural features designed for defense and dominance. First is the Motte, a massive man-made earthen mound that served as an elevated foundation for a tower. Second is the Bailey, a fortified courtyard or enclosure at the base of the motte where living quarters and stables were located. Third is the Keep (or Donjon), the central stronghold tower that provided a final refuge during a siege; these were originally wooden but later transitioned into massive stone rectangular structures. Fourth is the Curtain Wall, a thick defensive stone wall that eventually replaced timber palisades to encircle the entire castle complex. Fifth is the Moat, a deep, wide ditch (sometimes filled with water) dug around the exterior of the castle to deter attackers and prevent the use of siege towers or battering rams. These features combined to make Norman castles formidable symbols of power during the Middle Ages.