A castle is a type of fortified structure built during the Middle Ages predominantly by the nobility or royalty and by military orders. Scholars usually consider a castle to be the private fortified residence of a lord or noble. This is distinct from a mansion, palace and villa, whose main purpose was exclusively for pleasance and are not primarily fortresses but may be fortified. Use of the term has varied over time and, sometimes, has also been applied to structures such as hill forts and 19th- and 20th-century homes built to resemble castles. Over the Middle Ages, when genuine castles were built, they took on a great many forms with many different features, although some, such as curtain walls, arrowslits, and portcullises, were commonplace.
Dating back to the early 12th century, the Alcázar of Segovia, Spain, is one of the most distinctive castles in Europe.
Built in 1385, Bodiam Castle in East Sussex, England, is surrounded by a water-filled moat
The Norman White Tower, the keep of the Tower of London, exemplifies all uses of a castle including city defence, a residence, and a place of refuge in times of crisis.
Windsor Castle in England was founded as a fortification during the Norman Conquest and was one of the principal official residences of Queen Elizabeth II during her reign.
A fortification is a military construction designed for the defense of territories in warfare, and is used to establish rule in a region during peacetime. The term is derived from Latin fortis ("strong") and facere.
Castillo San Felipe del Morro, Puerto Rico. The fortress and walled city of Old San Juan are a UNESCO World Heritage Site.
Castillo San Felipe de Barajas, Colombia. Cartagena's colonial walled city and fortress were designated a UNESCO World Heritage Site.
Maiden Castle in 1935. The Iron Age hillfort was first built in 600 BC.
Early 20th century aerial photograph of the fortifications of Valletta, Malta, which were built in the 16th and 17th centuries.
