Jotunheim

The land of the Frost Giants or Jotunn. The Jotnar were the sworn enemies of the Aesir and were constantly at war with one another, however there were Jotnar who had love affairs with the Aesir, Thor and Odin both had a few Jotunn lovers according to mythology. Loki was in fact a Jotunn himself but was accepted into  Asgard as Odin's son and Thor's brother  (I should point out that in the sagas it has never been confirmed if Loki was adopted by Odin or simply included in the royal family as an extra.) Jotunheim was separated from Asgard by the river Iving which despite Jotunheim's sub-zero temperatures never froze over.

Jotunheim was believed to be a frozen tundra, consisting of rocks and dense forests. The Jotunns were forced to hunt animals from the forests and fish from the rivers due to the infertile land of Jotunheim. The world itself was believed to have been created from the Giant Ymir's head, who was as previously mentioned killed by Odin and his brothers.

(Image sourced; http://norse-mythology.org/cosmology/the-nine-worlds/jotunheim/)