 The composite set (with both exteriors and interiors) consisted of a large section of Castle Black including the courtyard, the ravenry, the mess hall, and the barracks, and used the stone wall of the quarry as the basis for the ice wall that protects Westeros from the dangers that dwell beyond.They also made a functional elevator to lift the rangers to the top of the Wall.A castle with real rooms and a working elevator were built near a cliff high.