 After the Franks were driven from the Holy Land in 1291 , European familiarity with the castles of the Crusades declined . It was not until the 19th century that interest in these buildings was renewed , so there are no detailed plans from before 1837 . Guillaume Rey was the first European researcher to scientifically study Crusader castles in the Holy Land . In 1871 he published the work Etudes sur les monuments de l 'architecture militaire des Croisés en Syrie et dans l 'ile de Chypre ; it included plans and drawings of the major Crusader castles in Syria , including Krak des Chevaliers . In some instances his drawings were inaccurate , however for Krak des Chavaliers they record features which have since been lost . 
