 On April 1 , 2007 , the crew began filming at Barrandov Studios in Prague . There , sets such as Miraz 's castle , Aslan 's How and the underground hiding places of the Narnians were created . The 200 @-@ foot @-@ tall ( 61 m ) castle was built to scale because Adamson felt he overused digital sets on the last film . The castle was built in the open air during winter , where the temperature would drop to minus 20 ° C. Miraz 's courtyard is the largest set in production designer Roger Ford 's career , including the previous Narnia film . Aslan 's How was modified into the hideout after filming for those scenes was finished . To create Trufflehunter 's den , Ford 's crew put a camera inside a badger 's den to study what it should look like . The den 's roof had to be raised by three inches because Ben Barnes was too tall . 
