Yggdrasil (The Terrible One's Horse) - The World Tree
The Yggdrasil has three roots: the first stands over Niflheimr in Hvergelmir; the second towards the Frost Giants in Mimisbrunnr (Mimir's Well); the third in heaven in the Well of Wyrd.
The messenger in the tree (and thus between the worlds) was the squirrel, Ratatosk. In the top of the tree was perched a giant eagle (with a hawk upon its forehead) who blew the winds over the worlds with his mighty wings. The roots of Yggdrasil were gnawed at by a dragon, Nidhogg. Heidrun, a goat, lived on top of the Yggdrasil and ate its leaves. Four stags fed on the bark of Yggdrasil, they represent the four winds. They are Dain, Dvalin, Duneyr, and Durathror. Beneath the tree are several serpents: Goin, Moil (sons of the gnawing wolf), Grabak, and Grafvolluth (the bewilderer and the bringer of sleep). Along with Nidhogg, they will gnaw the roots until the end of time.
Asgard - Homeland of the Aesir, the race of warrior gods. Located on the highest level of the Norse universe, it is surrounded by a high wall of closely fitted stone blocks. In the middle of Asgard lies the plain of Idavoll (or Ida) where the Aesir meet to decide important issues. There the gods assemble in the hall of Gladsheim and the goddesses in the hall of Vingolf. Midgard is in the center of Ginnungagap, an area of 11 rivers and frozen wasteland. It is Midgard that ties together all the other worlds.
Alfheim (elf home) - It is located on the highest level of the Norse universe. Also found on this level are the worlds of Asgard and Vanaheim. Alfheim is the palace of the god Freyr and the homeland of the elves of light. Alfheim lies near Asgard and is strongly associated with the Vanir.
Vanaheim (home of the Vanir) - This is the land of the Vanir. It is located in Asgard, on the highest level of the universe. Considered to be Njord's birthplace. Freyja's hall "Setrumes" is located here.
Mid Level worlds
Midgard (middle world) - This is the home of mankind. It is on the same level as Nidavellir (land of the dwarfs), Svartalfheim (land of the dark elves/dwarfs) and Jotunheim (the land of the giants). Midgard is surrounded by a vast ocean and a great wall created by the Gods to protect it.
Jotunheim - The homeland of the frost giants and rock giants. Situated in Midgard, on the middle level of the Norse universe, Jotunheim is separated from Asgard by the river Iving, which never freezes over. Mimir's well of wisdom is in Jotunheim, beneath the Midgard root of the ash tree Yggdrasil. 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.
Nidavellir - Land of the dwarfs. Nidavellir is located to the east of Midgard.
Svartalfheim - Land of the dark elves. Svartalfheim is to the south of Midgard.
Lower level worlds
Helheim (house of Hel) - This cold, dark and misty abode of the dead is located in the world of Niflheim, on the lowest level of the Norse universe. It can be reached by the road Helvergr. Hel's gates are called Helgrind. No one can ever leave this place, because of the impassable river Gjoll that flows from the spring Hvergelmir and encircles Helheim. The entrance to Helheim is guarded by Garm, a monstrous hound, and Modgud. The giant Hraesvelg ("corpse eater") sits at the edge of the world, overlooking Helheim. In the form of an eagle with flapping wings he makes the wind blow. Below Helheim, is Hel's mansion, called "Elvithnir" (misery) and is surrounded by a wall called "Fallanda Forad" (falling peril).
Niflheim (house of mists) - World of the dead. Those condemned as evil are shackled and driven to Niflhel by the Dark Elves. There they must drink burning venom and are subjected to the nine realms of torture. This is the world of pure ice.