Almost all the mountaineering challenges on Mount Everest have now been overcome, but there remain two routes with extraordinary difficulties: a direttissima climb up the avalanche-prone East Face - the only yet unclimbed direct route on Everest, and ascent of the north pillar on the East Face over the (according to George Mallory) so-called Fantasy Ridge. This ridge ends at the centre of the northeast ridge - below the Three Pinnacles. A climber wishing to climb up the Fantasy Ridge on his way to the summit would have to negotiate the east ridge and then climb the Three Pinnacles on the northeast ridge.