 The northern ridge is four kilometres long and has the vitrified fort of Dùn Deardail ("Fort of the Red Eye") near its terminus just before it joins Glen Nevis.The fort is probably named after Deirdre, the princess of Ulster, it is one in a line of vitrified forts that stretches from Craig Phàdraig outside Inverness to the west coast.The north east ridge also descends to Glen Nevis but is much shorter.