“Oathkeeper” Filming Locations
Game of Thrones episode “Oathkeeper” was filmed in Dubrovnik & Split in Croatia and in the United Kingdom.
Klis Fortress as Walls of Meereen
Daenerys crucifies the Masters on the walls.
Source: Winter Is Coming
Diocletian’s Palace as Tunnels under Meereen
Grey Worm leads some Unsullied into Meereen through the sewers and begins a slave uprising.
Source: Splitski Portal
Magheramorne Quarry as Castle Black
Home of the Nights Watch at the base of The Wall where Jon Snow travels. Photos of the set constructed in the disused quarry can be found here. One of the quarry walls was painted to look like ice, all of the buildings around the courtyard were built (including several interiors) as well as a working elevator.