At the center of Norse cosmology stands Yggdrasil, the mighty world ash tree that connects the nine worlds. For orientation, they are often grouped into three levels – though the sources don't always define this division clearly.
Upper World: Asgard, home of the Æsir, Vanaheim, world of the Vanir, and Alfheim, realm of the light elves.
Middle World: Midgard, world of humans, surrounded by Jötunheim, land of the giants, and Nidavellir, home of the dwarves.
Lower World: Helheim, the realm of the dead, Niflheim, world of ice, and Muspelheim, realm of fire.
