Stone keep castles became the norm during the 11th and 12th centuries, especially during the Norman Invasion of England. They were largely constructed by William the Conqueror, and his barons, who wanted to show their power and status on their new lands.

Stone keeps, or "Great Towers," were built primarily as the ultimate defensive stronghold and a symbol of permanent political authority during the Middle Ages. Replacing earlier "motte-and-bailey" wooden structures, stone keeps provided superior protection against fire—the greatest threat to medieval fortifications. Their massive walls, often 10 to 15 feet thick, were designed to withstand the impact of siege engines and make tunneling nearly impossible. Beyond defense, the keep served as the lord's primary residence and administrative center, projecting an image of invincibility and wealth to the local population. In 2026, historians emphasize that these structures were also "psychological weapons"; the sight of a stone keep like the White Tower in London was enough to quell rebellions before they even began, cementing the Norman or feudal grasp on the surrounding landscape for centuries.