<P> Roles that were recast for season 4 include Michiel Huisman as Daario Naharis . Huisman replaces Ed Skrein, who portrayed the character in season 3 . Dean - Charles Chapman plays the role of Tommen Baratheon, King Joffrey's younger brother . Tommen was played by Callum Wharry in seasons 1 and 2 . Chapman appeared as Martyn Lannister in two episodes of season 3 ("Walk of Punishment" and "Kissed by Fire"). Hafþór Júlíus Björnsson was cast as Ser Gregor Clegane, called "The Mountain". Hafþór replaces Ian Whyte, who portrayed the character in season 2 . </P> <P> After an absence of at least a season, Owen Teale returns as Alliser Thorne, Kate Dickie as Lysa Arryn, Dominic Carter as Janos Slynt, Tony Way as Dontos Hollard, Andy Beckwith as Rorge, Gerard Jordan as Biter, Andy Kellegher as Polliver, Lino Facioli as Robin Arryn and Brian Fortune as Othell Yarwyck . </P> <P> Filming for the season began on July 8, 2013, in Northern Ireland . The series also returned to Iceland and Dubrovnik for filming . New locations in Croatia include Diocletian's Palace in Split, Klis Fortress north of Split, Perun quarry east of Split, Mosor mountain, and Baška Voda further down to the south . In the commentary for episode 2, "The Lion and the Rose," the showrunners revealed that parts of Joffrey's death scene had been filmed in California . The Thingvellir National Park in Iceland was used as the location for the fight between Brienne and The Hound . </P> <P> Filming for the season lasted 136 days and was completed on November 21, 2013 . </P>

Where was season 4 game of thrones filmed