Motte and bailey
A motte and bailey is a type of castle design that first appeared during the Norman period and spread from France to England with the Norman Invasion of 1066. It was constructed by raising a small hill, with a tower on top which was then surrounded by a fence or wall. This type of castle was relatively quick and easy to build. The tower and fence could be constructed of wood and yet still offer a strong defence. The motte had to be carefully constructed to prevent its collapse under the weight of the wall. Usually layers of earth, stone and gravel were used to reinforce the surface.
Later, most motte and bailey castles were constructed with stone towers and walls. Some of these towers, often called Great Towers, have survived. The most well known are probably the White Tower, often known as the Tower of London and Colchester Castle in England's oldest recorded town. In both cases these were built from the reused remains of Roman fortifications.