Scotland contains the most mountainous terrain in Great Britain. Much of the highest uplands lie to the north and west of the Highland Boundary Fault in the Northwest Highlands and Grampian ranges. The jagged Cuillin, on the Isle of Skye, represents a major mountain range that is not located on the Scottish mainland. Located at the western end of the Grampian Mountains, at an altitude of , Ben Nevis is the highest mountain in Scotland and Great Britain. Ben Macdui and Braeriach are, respectively, the second and third tallest peaks in Scotland. Both are located in the Cairngorms, a mountain range in the eastern Highlands which is the highest upland area in Britain.