Ben Macdui (, meaning "MacDuff's mountain") is the second-highest mountain in Scotland and all of the British Isles, after Ben Nevis, and the highest of the Cairngorm Mountains. The summit is above sea level and it is classed as a Munro. Ben Macdui sits on the southwestern edge of the Cairngorm plateau, overlooking the Lairig Ghru pass to the west, and Loch Etchachan to the east. It lies on the boundary between the historic counties of Aberdeenshire and Banffshire. Before the production of accurate maps of Scotland in the 19th century, it was not known for certain that Ben Nevis was the highest point in Britain, and it was often thought that Ben Macdui might be higher. Following surveys of both peaks in 1846–47, Ben Nevis was confirmed as the higher. The summit of the mountain has a direction indicator erected in 1925 by the Cairngorm Club of Aberdeen in memory of former president Alexander Copland. The indicator shows the directions of the most noteworthy mountains that can be seen from the summit in clear weather. Snow patches have been known to persist at various locations on Ben Macdui, most notably Garbh Uisge Beag. The mountain is said to be haunted by the legendary Am Fear Liath Mòr (Big Grey Man). History After the defeat of Domnall mac Uilliam in 1187, Donnchad II, Earl of Fife, acquired Stratha'an, a territory stretching from Ballindalloch to Ben Macdui. Because the mountain marked the western boundary of Donnchad's territory, Gaelic scholar historian F.C. Diack and place-name scholar Professor G.W.S. Barrow have suggested that the mountain took its name from Donnchad's family, the Mac Duibh. Another suggestion is that the name comes from the Gaelic for "black pig", , referring to its shape. A 19th-Century Ordnance Survey name book suggests the name signifies "The Black Son mountain". In 1810 a Rev Dr Keith surveyed the heights of several Cairngorm summits using a barometer, estimating the height of Ben Macdui to be . This sparked interest in whether it, or Ben Nevis, was the highest summit in Scotland. The Ordnance Survey built a trig point on the summit in 1847 in order to accurately survey the height, confirming that Ben Nevis was indeed the higher. The surveyors also built a small shelter that became known as the "Sappers' Bothy", the remains of which can still be seen. Following these surveys, there were plans to build