Medieval castle designs have varied from one era of history to another. During the early and middle medieval times, the primary purpose of medieval castles was defence and thus little attention was paid to the aesthetics and design of medieval castles. However, during the late medieval times, the importance of medieval castles for defence gradually declined and more attention was paid to medieval castle designs.
Before the Norman Conquest of England, during the early medieval times, medieval castles merely consisted of mounds of earth with fortifications for defence. The Normans gave rise to special medieval castle designs called Motte and Bailey Castles. These castles consisted of a large mound of earth and an accompanying flat land area. The mound of earth was generally surrounded by a ditch of water for defence.
By the late medieval times, medieval castle designs had been drastically altered. Castles were built with large stones and increasing attention was paid to their design. It was also during the late medieval times that concentric medieval castles became popular. These castles consisted of two layers of castle walls which made penetration by an invading army very difficult. The inner wall was higher than the outer wall so that the outer wall could be defended from the inside as well.
Certain features were common to most medieval castles. These features included barbicans, deep moats, and great halls. Concentric castles were generally considered to have best medieval castle design in terms of defence and safety. However, in terms of aesthetics, best design could vary from castle to castle. Secret passages and stairways were also important components of the best medieval castle designs.
Medieval castles were built by men who were known for their architectural prowess and enjoyed success in their profession. One of the most famous builders was Gundulf who came to England after the Norman Conquest and was employed by William the Conqueror to build the castle at Rochester as well as the keep of the Tower of London. Among the other popular medieval castle builders, James of St. George and William Wynford were particularly noteworthy for their skill.
The most important purpose of medieval castles, particularly during the reign of William the Conqueror, was defence. Due to this reason, most of the castles were built at strategic locations in order to foil enemy invasions and ensure a strong hold over the local population. Major castles were built in and around important towns including London, York, Exeter, Cambridge, and others. Other than important towns, castles were also built on important river crossings and crossroads.
During the transition from middle to late medieval times, several critical changes were brought about in the medieval castle designs and construction strategies. The important transition took place after the Norman Conquest of England. During the middle medieval times, defence was the most important purpose for building of medieval castles while design of medieval castles and their aesthetics became increasingly important during the late medieval times.