Mourne Mountains

Where it sits. The Mournes occupy the south-eastern corner of County Down, a compact granite range roughly twenty-five kilometres across, rising almost straight out of the Irish Sea at Newcastle and running inland toward Rostrevor and Carlingford Lough. Twelve summits pass 600 metres; Slieve Donard tops out at 850 metres, the highest ground in Northern Ireland, and from its cairn the view can take in the Isle of Man, the Wicklow hills, Snowdonia and the Scottish coast on an exceptional day. The range is unusually abrupt — there are no foothills to speak of on the seaward side, and the change from beach to mountain happens within three kilometres.

The story behind it. The Mournes are the eroded roots of granite bodies intruded about fifty-six million years ago during the same phase of volcanic activity that built the Antrim basalts and the Giant's Causeway. Later glaciers scooped out the valleys and left the tors and boulder fields that make the ridges look deliberately arranged. Human use of the high ground was mostly grazing and quarrying; the pale Mourne granite went into Belfast kerbstones and into docks as far away as London. The single most striking structure is the Mourne Wall, a drystone granite wall about 1.5 metres high and 22 miles long, built between 1904 and 1922 by the Belfast Water Commissioners to fence off the catchment feeding the city's reservoirs. It crosses fifteen summits, was raised entirely by hand by teams working through the summer months, and today doubles as a navigation aid and as the route of the Mourne Wall Challenge. The Silent Valley Reservoir, completed in 1933, and Ben Crom above it sit inside that enclosure. C. S. Lewis, who holidayed nearby, drew on this landscape when he imagined Narnia.

On screen. The Mourne foothills carried one of the most memorable early locations of Game of Thrones. Sandy Brae, an area of open, boulder-strewn upland grazing on the southern side of the range near Attical, was dressed as Vaes Dothrak, the Dothraki city in the far east of Essos, for the first season. The tents, the horse lines and the great gate of the horse city were built on that grass, and Daenerys Targaryen's journey with Khal Drogo's khalasar was filmed on the surrounding slopes. It is a private working hill farm and there is no visitor access to the exact site, which is worth knowing before setting out. Tollymore Forest Park, at the northern foot of the range, was the production's other Mourne base and is fully open.

What you actually see today. The classic outing is Slieve Donard from Newcastle, following the Glen River past the old ice house and up to the col at the Mourne Wall, then along the wall to the summit tower — about nine kilometres round trip and 850 metres of ascent, typically four to five hours. Quieter alternatives include the Brandy Pad, an old smugglers' track under the Slieve Beg cliffs; Hare's Gap, the most dramatic pass in the range; Slieve Binnian's summit tors above the Silent Valley; and the Slieve Gullion and Rostrevor forest side for tree cover in bad weather. The Silent Valley has a visitor centre, café and shuttle bus to Ben Crom in season, and is the one part of the high ground that a non-walker can reach easily. Rock climbers work the granite slabs at Hen Mountain and the Spellack crag; sea-level walkers can take the coastal path from Bloody Bridge, named for a massacre of prisoners in 1641, where the river runs over pink granite slabs straight into the sea. Kilbroney Park above Rostrevor holds the Cloughmore Stone, a forty-tonne glacial erratic that legend assigns to a throw by Finn McCool, with a view down Carlingford Lough to the Cooley peninsula in the Republic.

Getting there and timing. Newcastle is the northern gateway, ninety minutes from Belfast by the A24, with regular buses; Kilkeel, Annalong and Rostrevor serve the south and west. There is no public transport into the mountains themselves, and parking at popular trailheads such as Carrick Little, Trassey and Bloody Bridge is limited and fills early on fine weekends. This is serious hill country despite modest heights: the weather changes fast, cloud can sit on the tops for days, and the granite blockfields are ankle-breaking in poor visibility, so a map, compass and the ability to use them matter more than the altitude suggests. May to September gives the most settled conditions and the longest daylight; winter brings genuine snow cover and full winter conditions on the ridges. The area is an Area of Outstanding Natural Beauty and has been repeatedly proposed as Northern Ireland's first national park.