 The second phase of building work undertaken by the Hospitallers began in the early 13th century and lasted decades . The outer walls were built in the last major construction on the site , lending the Krak des Chevaliers its current appearance . Standing 9 metres ( 30 ft ) high , the outer circuit had towers that projected strongly from the wall . While the towers of the inner court had a square plan and did not project far beyond the wall , the towers of the 13th @-@ century outer walls were rounded . This design was new and even contemporary Templar castles did not have rounded towers . The technique was developed at <unk> Gaillard in France by Richard the <unk> between <unk> and <unk> . The extension to the southeast is of lesser quality than the rest of the circuit and was built at an unknown date . Probably around the 1250s a <unk> was added to the north wall . 
