The primary difference between Norman and Saxon "castles" lies in their design, material, and purpose. Strictly speaking, the Anglo-Saxons did not build "castles" in the medieval sense; they built burhs, which were large, fortified communal settlements or towns designed to protect a whole community behind earthwork walls and wooden palisades. In contrast, Norman castles, introduced after the 1066 invasion, were private military strongholds designed to control a hostile population. The classic Norman design was the motte-and-bailey: a large man-made mound (the motte) with a wooden or stone tower on top, surrounded by an enclosed courtyard (the bailey). While the Saxons focused on horizontal, community-wide defense using the natural landscape, the Normans emphasized verticality and intimidation. Over time, the Normans transitioned from timber to massive stone "keeps," such as the White Tower at the Tower of London. By 2026, archaeological studies have highlighted that while Saxons were experts at fortified urban planning, it was the Normans who brought the specific concept of a lord's private, defensible stone residence to the British Isles.