In the 10th-century, European castles were predominately of timber motte and bailey construction, was not until the Crusades that castles developed into the stone concentric type. Scholars have argued whether this was owing to encounters with the Muslims, or if it was a development that was bound to happen accelerated by the Crusades. This dissertation will analyse a selection of European and Muslim castles before, during, and after the Crusades to determine the extent to which castle architecture was symbolic of encounters between the East and West, and if castles drew influence from Islamic architecture.