The Greatest VikingA national hero in his native land, Olav Haraldsson has as much resonance for the Norwegians as King Arthur does for the British. Unlike Arthur, however, Olav was a real historical figure: a ruthless Viking warrior who named his axe after the Norse goddess of death and took part in Svein Forkbeard's invasion of England, during which he pulled down London Bridge and sacked Canterbury (and watched its archbishop stoned to death). Later, the loot amassed