the idea of the 9 worlds that Yggdrasil holds.
http://i.stack.imgur.com/GKEH7.png
http://img1.wikia.nocookie.net/__cb20120401114359/avengersearthsmightiestheroes/images/4/4f/Nine_realms.png
http://asgardian.shrine.angelfire.com/the-nine-worlds-of-the-norse-cosmology.html
The 9 realms
Asgard - Home of the gods
Vanaheim - home of the vanir powerful but peaceful fertility deities
Alfheim - The world of the light elves
Svartalfheim- home of the dark elves
Midgard - Earth
Jotunheim - realm of the giants
Nidavellir - a rocky realm home to the dwarves
Helheim (or Hel) - realm of the common dead, people neither truly heroic or evil
Niflheim - frozen wasteland bitter realm of the dishonoured
