Ben Macdui, with its two neighbouring peaks Carn a' Mhaim and Derry Cairngorm, form the central massif of the Cairngorms between the two great passes, the Lairig Ghru and the Lairig an Laoigh. Ben Macdui is a huge dome with fairly steep slopes all round except to the north where a great plateau extends to Cairn Gorm. Carn a' Mhaim is joined to Ben Macdui by a long narrow ridge which drops precipitously on its west side into the Lairig Ghru. Derry Cairngorm forms a long ridge on the west side of Glen Derry with its prominent summit cone at the north end. Start from the carpark at the foot of Glen Lui and go up the glen and its continuation along Glen Luibeg. After crossing the Luibeg Burn climb the easy slopes of Carn a' Mhaim, whose summit is a very fine viewpoint for the great mountains at the heart of the Cairngorms. Continue along the north ridge, which is narrow and exposed on its west side, and at its end climb north-east to the summit of Ben Macdui. Descend east then north-east by a path which drops towards Loch Etchachan, but before reaching the loch turn south-east along the ridge of Derry Cairngorm. Continue over the bouldery summit cone and along the ridge over Carn Crom to Derry Lodge and the road down Glen Lui.