Jotunheim, one of the nine worlds of Norse Cosmology. The world of the Jotuns,
also known as giants. Comparing to some of the other nine worlds, there is not too much information available from the mythology or history.
Looking at Yggdrasil, the world tree, there are three levels. Jotunheim, along with Midgard, is located in the middle level. Some depictions claim that Asgard is also found on this middle level, while others say ASgard is found at the top of Yggdrasil. I shall leave that decision up to you.
While Asgard is separated and connected to Midgard by Bifrost, the rainbow bridge, Jotunheim is said to be separated from Asgard by the river Iving. Which in the winter freezes over, and gives the Jotuns a better chance of crossing the river. Luckily, Thor protects both Asgard and Midgard from the dangers that may cross the frozen river.
Mimir's Well, the well of wisdom where Odin sacrificed his eye, is also located within Jotunheim, at the base of one of Yggdrasil's three roots.
"Jotunheim is ruled by Thrym ("uproar"), the feared king of the frost giants. The stronghold of Utgard, the chief city of Jotunheim and the abode of the giants, is ruled by the giant Utgard-Loki. Other strongholds include Gastropnir, home of the giantess Menglad, and Thrymheim ("house of uproar"), mountain stronghold of the giant Thiazi." (1)
"In the Eddas, the dwelling-places of the giants are described as deep, dark forests, mountain peaks where winter never eases its grip, and similarly inhospitable and grim landscapes, and this certainly seems to be how the heathen Norse and other Germanic peoples symbolically visualized the invisible Jotunheim itself." (2)
Yggdrasil, the World Tree. (ralphiesportal.me)
Tolkien and Norse Mythology (cjadrien.com)
Yggdrasill - The World Tree (sealandandsky.wordpress.com)
For more on the residents of Jotunheim see: