In Norse mythology, Valhalla (or Val-hall) is a giant hall. In it, Odin's Valkyries preside over all those warriors which were slain in battle, and deeemed worthy to attend. The Valkyries also choose the warriors. These warriors will fight on Odin's side at Ragnarök, the battle at the end of the world.
Valhalla, Hall of the Slain, is presided over by Odin. This vast hall has five hundred and forty doors. The rafters are spears, the hall is roofed with shields and breast-plates litter the benches. A wolf guards the western door and an eagle hovers over it. It is here that the Valkyries, Odin's messengers and spirits of war, bring half of the heroes that died on the battle fields (the rest go to Freya's hall, Folkvang). These heroes, the Einherjar, are prepared in Valhalla for the oncoming battle of Ragnarok. When the battle commences, eight hundred warriors will march shoulder to shoulder out of each door. When the doors are opened you can see the army of the gods who will kill all who threaten them.