A castle is a defensive structure seen as one of the main symbols of the Middle Ages. The term has a history of scholarly debate surrounding its exact meaning, but it is usually regarded as being distinct from the general terms fort or fortress in that it describes a building which serves as a residence and commands a specific territory.
Roman forts and hill forts were the main antecedents of castles in Europe, which emerged in the 9th century in Carolingian France. The advent of cannon and gunpowder changed the needs of warfare in Europe, limiting the effectiveness of the castle and leading to the rise of the fort.

Here you can find more then 40 high resolution(2000x1333)  photografs of castles all over the world

Castle Photo Gallery. Castle studies on history, architecture, design, and preservation

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