In Norse belief, the universe was not one world. It was nine, all connected by a giant tree whose roots held everything together. Some realms were bright and full of light. Some were frozen wastelands. One was a dark underground kingdom ruled by the daughter of a trickster god. And all of them were heading toward the same ending — a fire that would consume everything, from which something new would eventually rise.
The Vikings did not believe the universe was one place. They believed it was nine, all of them existing in and around the roots and branches of an enormous tree called Yggdrasil that stood at the center of everything. Some of these realms are well known today — Asgard shows up in Marvel films, Midgard is a word gamers recognize, Ragnarök has been turned into a Netflix show. But most people have only a loose sense of what the actual Norse cosmological picture looked like, which nine worlds existed, who lived in them, and how they all related to each other. The answer is more complicated than pop culture suggests, and it has an extra layer of difficulty built in: we do not have a complete, reliable, original account of the nine realms. What we have are fragments of old poetry, a medieval Icelandic scholar writing two centuries after the Viking Age ended, and the knowledge that his account was shaped by his Christian faith in ways that changed some of what he recorded. The nine realms described below are the best reconstruction we have — but they should be understood as a reconstruction, not a photograph.
Yggdrasil stood at the center of the Norse universe, its branches reaching the heavens and its three great roots extending into different realms — the home of the gods, the realm of the giants, and the well of the dead.
Why the Sources Are Tricky
Norse religion had no written scripture. It was oral — stories told, poems recited at court, beliefs passed from one generation to the next through memory and performance rather than through books. The older poetic sources that survive, the Eddic and Skaldic poetry, assume you already know the cosmology. They drop names and references without explaining them, the way someone might mention a mutual friend without introducing them. For modern readers, they are full of gaps. The most complete account we have comes from Snorri Sturluson, an Icelandic chieftain who lived from 1179 to 1241 CE and wrote down the Norse myths in his Prose Edda. Snorri was brilliant and thorough, and Norse mythology as most people know it today largely comes from him. He was also a Christian writing for a Christian audience, roughly two centuries after the Viking Age had wound down, and he reworked the older material to make it fit a more structured, readable form. One visible result of this is the realm of Hel. Most scholars today believe the concept of Hel as a fully realized underworld realm is partly or entirely a Christian addition — the Norse had a vague concept of a dark realm of the dead called Niflhel in older literature, but the developed Hel that Snorri describes looks a lot like it was shaped by Christian ideas about the afterlife. There are other places where Snorri seems to have merged things that were originally separate or clarified things that were deliberately ambiguous. With all that said, his account is still what we work from, because it is the most complete one we have.
Before the Realms: How Everything Started
Before the nine realms existed, there was Yggdrasil and there was the void. Nobody explains where the tree came from. It simply was, standing in the misty emptiness of Ginnungagap, bordered on one side by Muspelheim's fire and on the other by Niflheim's ice. Eventually the fire melted the ice, and two things came out of the resulting mist: Ymir, the first giant, and Audhumla, a cow who fed him. Audhumla survived by licking salt from the ice, and in doing so she gradually uncovered a figure named Búri — the ancestor of the gods. Búri's son Borr mated with Bestla, a giantess, and they had three sons: Odin, Vili, and Vé. Meanwhile, Ymir was reproducing on his own through autogamy — a male and female giant grew from his left armpit while he slept, and a son came from his legs. These became the ancestors of all the giants who would spend the rest of Norse mythology as the enemies of the gods. Odin and his brothers killed Ymir. The blood that poured from the body drowned every giant except one, Bergelmir, who escaped on a raft with his wife and eventually repopulated the giant race. Odin, Vili, and Vé dragged Ymir's enormous body to the void and built the world from it. Flesh became earth. Skull became sky. Bones became mountains. Blood became the sea. Later, walking along the shore, the three gods found two trees — an ash and an elm — and made the first man, Ask, from the ash and the first woman, Embla, from the elm. The nine realms took shape around all of this.
The Norse creation story is built on an act of violence — Odin and his brothers killed the first giant Ymir and used his body as raw material for the world, his blood becoming the seas that nearly drowned every giant alive.
Asgard — Home of the Gods
Asgard is where the Aesir gods lived — Odin, Thor, Loki, Baldr, Týr, Heimdall, and the rest of the main Norse pantheon. In Snorri's account it sits in the heavens, connected to the human world by Bifrost, the rainbow bridge. Some scholars think the original Norse conception had Asgard on the same level as the human world rather than above it, but Snorri's celestial city of high towers surrounded by walls is the version most people know. Odin's great hall Valhalla was in Asgard — the place where warriors who died in battle were brought to feast and train, preparing for Ragnarök. There is also mention of Hildskjalf, a high seat or place from which Odin could look out over all nine realms and see everything happening in them. Whether Hildskjalf was a separate building or just his throne is not entirely clear from the sources. Asgard was also home to some Vanir gods. When the Aesir-Vanir War ended in a peace treaty, hostages were exchanged between the two divine families. The Vanir god Njord and his children Freyr and Freyja came to live in Asgard, while Aesir gods went to Vanaheim. So even the gods' home realm was a mix of both divine families after the war ended.
Midgard — The Human World
Midgard is the realm of human beings, and the gods built it specifically to protect Ask and Embla and their descendants from the giants. The Prose Edda describes it as a circular realm surrounded by the deep sea, with the gods using Ymir's eyelashes to build a fortress wall around it — which is one of the stranger construction projects in any mythology, but consistent with the Norse habit of using giant body parts for everything. The sea around Midgard is home to the Midgard Serpent, also called Jörmungandr — a monster so large it wraps completely around the human world and bites its own tail. Thor's most famous enemy, it will break free at Ragnarök and help bring about the end of everything. Midgard sits between Asgard above and Jotunheim nearby. The rainbow bridge Bifrost connects it to Asgard. The giants in Jotunheim are separated from it, but not by enough distance to make the gods comfortable — hence the wall.