Slieve Donard, Mountain summit in County Down, Northern Ireland

Slieve Donard is the highest mountain in Northern Ireland, rising to 850 metres at the northeastern edge of the Mourne Mountains above Newcastle. Its broad, rounded summit is capped with pale stone and moorland, with a thin path climbing the right-hand slope. The Mourne Wall runs up the western and southern slopes to a small stone tower at the top.

Two prehistoric burial cairns sit at the summit, with the Great Cairn dating to 3300-3000 BC. This marks the highest passage tomb in Britain and Ireland.

The mountain's older names, Beann Boirche and Sliabh Slángha, refer to a mythical cowherd-king and to Slángha, said to be Ireland's first physician, who was buried in the summit tomb. The modern name honours Saint Donard, a follower of Patrick said to have used the Great Cairn as a hermit's cell. A late-July pilgrimage to the top continued until the 1830s, likely a Christianised Lughnasadh ritual.

The main hiking trail begins in Newcastle and passes through Donard Forest alongside the Glen River. It connects with the Mourne Wall path for the final approach to the summit.

The Mourne Wall runs up the western and southern slopes and meets a small stone tower at the summit. The tower is a dry-stone shelter, and the wall was built in the early 20th century to enclose the water catchment area of the Silent Valley Reservoir.