The design of castles evolved over time as builders responded to developments in military strategy and improvements in technology. Although changes to castles happened bit by bit, with existing castles being upgraded and adapted rather than being torn down and rebuilt, several distinct castle types can still be identified.
Motte and Bailey Castles
A motte-and-bailey castle consisted of a motte (a large mound of earth) and a bailey (a levelled courtyard located next to the motte). On top of the motte usually sat a keep. The motte and the bailey were protected by a ditch, and palisade fences (a stockade made from large wooden stakes) often encircled the bailey, too
Find out more about motte and bailey castles.
Castles with Stone Keeps
Although motte and bailey castles were relatively quick and inexpensive to construct, they were susceptible to fire and the walls could be breached by determined attackers. Stone soon became the preferred building material for castles. The motte was essentially replaced by a strong stone keep. The keep was then surrounded by a thick stone curtain wall.
The keep was usually accessed by steps leading up to the first floor. The living space was located on the top floors and the kitchens were on the lower floors.
The early stone keeps were rectangular in shape, but they were later replaced with circular or semi-circular keeps, often referred to as shell keeps.
Concentric castles were made up of a series of circular walls. The inner walls were the highest and turrets were incorporated within the walls. The outer walls were lower than the inner walls (to allow archers on the inner walls to fire at attackers over the outer walls). A moat often encircled the entire castle, providing another obstacle for the attackers to overcome.
Some concentric castles still incorporated a central keep (see image below), whereas in others the chambers and castle buildings would often be constructed against the inner walls.
This design meant that attackers would have to work they way through several walls before they could take the castle. As one wall looked like it was going to be breached, the defenders could retreat to the next wall back. (Find out more about concentric castles).
As gunpowder technology improved, and canons became more powerful and more accurate, castles became less relevant from a purely defensive standpoint. Even the strongest stone walls could eventually be destroyed by canon fire.
However, castles were still relevant as a status symbol – a way of demonstrating wealth, strength and power to the rest of the world.
From the 15th century onwards, many fortress castles were adapted to make them more comfortable as homes. New castles, however, stopped being built, as the rich opted to construct grand palaces instead.
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