A motte and bailey castle consists of a man-made hill (the motte) supporting a tower and a walled yard (the bailey). (...) Early castle builders look… - Marilyn Stokstad

Castles were more than military posts; they were the centers of political and economic power. As government headquarters they were built to impress the local population as well as visitors and rivals. While power was spread among great tenants-in-chief in a system of delegated government, castles in each territory were places where local lords collected taxes, settled disputes, and administered justice.

By the time Henry II Plantagenet (r. 1154–89) was crowned king of England in 1154, baronial castles outnumbered royal castles. A tough, dynamic ruler, Henry began to rectify the situation at once. In the north, King Malcolm of Scotland surrendered to him, giving Henry significant castles in Scotland and in the border territory. Many older castles like Windsor were strengthened. At Dover the masonry great tower and fore building were built in the 1180s, and concentric walls with half-round towers were added by Richard the Lion Hearted seventeen years later.

Ninth-century castles were relatively small and simple affairs designed to safeguard a relatively small number of people and intended as a refuge during times of trouble.