The first castle appeared in Britain sometime shortly of 1066, when William the Conqueror won the Battle of Hastings. The Norman invaders built motte and bailey type castles to quickly secure their new realm. The castle rapidly spread throughout Britain and soon, many new castles appeared on the scene. They mainly served a defensive purpose, but also acted as the center of a lord's domain and as an administrative center. As time went on, there was not the urgency to throw up rapid defenses, and new types of castles began to appear such as the masonry tower. The Tower of London is one of the most famous castles of this type.

Castles of this style were built for over two centuries but, following the Crusades, new varieties were adopted. While in the Middle East, the Crusaders got a look at the Byzantine castles and borrowing from that made new advances in seige warfare and defense. When they took the information back to Britain and applied a it, a new type of castle was born. It was called the concentric castle and and this method was adopted to either modify existing castles or to build new ones. A large number of these large, imposing concentric castles were built by Edward I in what he called the "iron ring". He had already put down two Welsh rebellion and did not fancy the thought of engaging in a costly war.

Castles of all types were built, and rebuilt, and added on to over the next 500 years or so. In the 16th century they began to lose favor. The use of gunpowder on the battlefied made them an ineffective defense. A castle that was once be considered invulnerable, could now be breached in a single day with the use of heavy artillery.

Castles were not abandoned though, instead they were adapted. The castle became a manor house and provided a somewhat comfortable way of life. It was no longer the center of administration and fortification. The modernization of war required that the two be separated.

Many of the castles were again called upon to fulfill a military role during the British Civil War when they were used as strongholds. After the war was settled, they were "slighted" or made militarily unusable by parliamentarians.